JP4596116B2 - Crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores, method for producing the same, and method for producing methylamines using the same - Google Patents

Description

【００８６】
【表２】

【００８７】
水酸化テトラエチルアンモニウムの使用量を、Al₂O₃に換算したアルミニウム化合物のモル数に対して1.0倍量以下とし、第１工程の水熱処理を80℃から130℃の間の温度ではあるものの１時間未満しか行わなかった比較例１〜３、５、６の触媒には、８員環SAPOではないAFI型構造体が見られ、結晶化度は低かった。また、これらの触媒を用いた反応のメタノール転化率及びジメチルアミン選択率は低いものであった。これに対し、第１工程の水熱処理を80℃から130℃の間の温度で１時間以上かけて行った実施例１〜９の触媒には、AFI型構造体、JCPDS番号20-0045化合物は見られず、結晶化度も良好であった。また、これらの触媒を用いた反応のメタノール転化率及びジメチルアミン選択率は、比較例１、２、５、６の触媒に比べて良好であった。特に、鋳型剤の水酸化テトラエチルアンモニウムを、Al₂O₃に換算した擬ベーマイトのモル数に対して0.75倍量用いて、第１工程について温度115℃と125℃で保持し１時間以上かけて水熱処理した実施例３と６の触媒のメタノール転化率とジメチルアミン選択率は、優れていた。比較例７〜９は、水酸化テトラエチルアンモニウムを、Al₂O₃に換算したアルミニウム化合物のモル数に対して1.0倍量以上用いて合成した例である。これらの例から、TEAOH/Al₂O₃のモル比が0.98を越えても、純粋なシャバサイト型の８員環SAPOは合成できるが、触媒収率が59〜66％と低く、触媒の生産性が低いことがわかった。また、メタノール転化率、ジメチルアミン選択率も、実施例１〜９の触媒に比べて低く、特に、板状結晶である比較例７の触媒性能は低かった。これらの例から明らかなように、従来、困難と考えられてきた少ない鋳型剤量でも、水熱処理の際の温度を制御することにより、純度、結晶化度、触媒性能の良いシャバサイト型の８員環SAPOが得られ、むしろTEAOH/Al₂O₃のモル比が0.75と小さい方が、結晶化度、触媒性能が優れていることがわかる。特に、比較例８と９は、特開2000−117114号公報記載の触媒調製例の合成再現性を調べた例であるが、比較例９のようにメタノール転化率が、再現しない場合があることがわかった。比較例４は、水酸化テトラエチルアンモニウムを、Al₂O₃に換算した擬ベーマイトのモル数に対して0.25倍量用いて合成した例であるが、得られた固体生成物は、JCPDS番号20-0045化合物の構造体であり、シャバサイト型の８員環SAPOは得られなかった。一方、水酸化テトラエチルアンモニウムを0.50倍量用いた実施例９では、純粋なシャバサイト型の８員環SAPOが合成でき、触媒性能も良好であった。
【００８８】
２．鋳型剤として水酸化テトラエチルアンモニウムとジエタノールアミン、シクロヘキシルアミンを用いた例
実施例１０は、鋳型剤として水酸化テトラエチルアンモニウムとジエタノールアミンの混合物を、実施例１１は鋳型剤としてシクロヘキシルアミンを用いたシャバサイト型の８員環SAPOの合成例である。得られた触媒の反応試験結果を表３に記載した。反応試験は、実施例１〜９と同様にして行った。
【００８９】
実施例１０
85wt%リン酸（41.51g）と純水（98.70g）、35wt%水酸化テトラエチルアンモニウム水溶液（42.10g）、及びジエタノールアミン（6.30ｇ）の均一な混合物を30℃以下に冷却し、これに擬ベーマイト（26.32g：SASOL GERMANY GmbH，PURAL NF，Aｌ₂O₃含有量77.5%）を撹拌しながら添加した。この混合物を１時間撹拌した後、シリカゾル（30.06g：日産化学工業株式会社，スノーテックスＮ，SiO₂含有量20wt%）と酸化ジルコニウム粉末（1.25g，第一稀元素化学工業株式会社，RC-100）を添加し更に30分間撹拌した。この混合物のモル酸化物比における組成は次の通りであった：0.50TEAOH：0.30DEA：1.0Al₂O₃：0.9P₂O₅：0.5SiO₂：0.05ZrO₂：45H₂O（DEAはジエタノールアミンを表す）。得られた混合物をステンレス製オートクレーブ中で、撹拌しながら水熱処理した。水熱処理は、内容物の温度で、第１工程として25℃から115℃までを65℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを65℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で35時間保持して行った。水熱処理時の圧力は自生圧とした。室温まで冷却した後、オートクレーブを開け、生成スラリーを遠心分離して沈殿を得た。得られた沈殿を200mlの純水で３回、洗浄・遠心分離したのち、80℃で12ｈ乾燥した。更に空気気流下、600℃で４時間焼成して、白色粉末（44.17g）を得た。触媒収率は85％であった。この粉末はＸ線回折の結果、純粋なシャバサイト型構造を有する８員環SAPOであり、AFI型構造体やJCPDS番号20-0045化合物のピークは見られなかった。結晶化度は良好で、1.03であった。粒子性状は、直方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、2.5μｍであった。原料流通開始後６ｈ目の反応成績を表３に示した。
【００９０】
実施例１１
85wt%リン酸（43.82g）と純水（145.50g）の均一な混合物を30℃以下に冷却し、これにアルミニウムトリイソプロポキシド（81.70g：ナカライテスク株式会社）を撹拌しながら添加した。この混合物を30分間攪拌した後、シクロヘキシルアミン（15.90g）を攪拌しながら添加した。この混合物を１時間撹拌した後、シリカゾル（24.05g：日産化学工業株式会社，スノーテックスＮ，SiO₂含有量20wt％）を添加し更に30分間撹拌した。この混合物のモル酸化物比における組成は次の通りであった：0.80シクロヘキシルアミン：1.0Al₂O₃：0.95P₂O₅：0.40SiO₂：47.5H₂O。得られた混合物をステンレス製オートクレーブ中で、撹拌しながら水熱処理した。水熱処理は、内容物の温度で、第１工程として25℃から115℃までを65℃/ｈで昇温し、115℃で５時間保持したのち、115℃から180℃までを65℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として180℃で35時間保持して行った。水熱処理時の圧力は自生圧とした。室温まで冷却した後、オートクレーブを開け、生成スラリーを遠心分離して沈殿を得た。得られた沈殿を200mlの純水で３回、洗浄・遠心分離したのち、80℃で12ｈ乾燥した。更に空気気流下、600℃で４時間焼成して、白色粉末（43.90g）を得た。触媒収率は84％であった。この粉末はＸ線回折の結果、純粋なシャバサイト型構造を有する８員環SAPOであり、AFI型構造体やJCPDS番号20-0045化合物のピークは見られなかった。結晶化度は良好で、1.00であった。粒子性状は、立方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、3.5μｍであった。原料流通開始後６ｈ目の反応成績を表３に示した。
【００９１】
【表３】

【００９２】
何れの例も、Al₂O₃に換算されたアルミニウム化合物のモル数に対して1.0倍量未満の鋳型剤量で、純粋なシャバサイト型構造を有する８員環SAPOが得られ、触媒性能も良好であることがわかる。
【００９３】
３．非晶質酸化物層の表面組成及び厚さと触媒性能との関係
実施例１２〜１７と比較例１０、１１は、シャバサイト型構造を有する８員環SAPOの非晶質酸化物層の表面組成、厚さと触媒性能に関する例である。各実施例及び比較例触媒の結晶粒子全体のSi/Alの原子比（バルクのSi/Alの原子比）、表面のSi/Alの原子比、表面のSi/Pの原子比、非晶質酸化物層の厚さを表４に、また、反応試験の結果を表５にまとめた。反応試験は、実施例１〜９と同様にして行った。
【００９４】
実施例１２
実施例２で得られた焼成粉末を、ICP及びXPSで分析した結果、結晶粒子全体のSi/Alの原子比は0.15であり、表面のSi/Alの原子比は0.60、表面のSi/Pの原子比は0.66であった。
【００９５】
実施例１３
実施例６で得られた焼成粉末を、ICP及びXPSで分析した結果、結晶粒子全体のSi/Alの原子比は0.14であり、表面のSi/Alの原子比は1.07、表面のSi/Pの原子比は1.24であった。
【００９６】
実施例１４
85％リン酸（89.8g）と純水（183.9g）及び、35wt%水酸化テトラエチルアンモニウム水溶液（122.9g）の均一な混合物に、擬ベーマイト（51.3g：SASOL GERMANY GmbH，PURAL NF，Al₂O₃含有量77.5%）を撹拌しながら添加した。この混合物を１時間撹拌した後、シリカゾル（46.8g：日産化学工業株式会社，スノーテックスＮ，SiO₂含有量20wt%）とチタニアゾル（5.3g，石原産業株式会社，STS-01，TiO₂含有量29.5wt%）を添加し、更に30分間撹拌した。この混合物のpHは2.95であり、モル酸化物比における組成は次の通りであった：0.75TEAOH：1.0Al₂O₃：1.0P₂O₅：0.4SiO₂：0.05TiO₂：50H₂O。得られた混合物を内容積0.6Lのステンレス製オートクレーブ中、700rpmで撹拌しながら、水熱処理した。水熱処理は、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で50時間保持して行った。水熱処理時の圧力は自生圧とした。室温まで冷却した後、オートクレーブを開け、生成スラリーを遠心分離して沈殿を得た。得られた沈殿を200mlの純水で３回、洗浄・遠心分離したのち、80℃で12ｈ乾燥した。更に空気気流下、600℃で４時間焼成して、白色粉末（88.2g）を得た。触媒収率は83％であり、良好であった。この粉末はＸ線回折の結果、純粋なシャバサイト型構造体であり、AFI型構造体、JCPDS番号20-0045化合物のピークは見られなかった。結晶化度は良好で、1.05であった。粒子性状は、立方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、2.2μｍであった。得られた焼成粉末の結晶粒子全体のSi/Alの原子比は0.16であり、表面のSi/Alの原子比は1.61、表面のSi/Pの原子比は2.45であった。また、走査透過型電子顕微鏡観察より、焼成粉末の結晶粒子は、厚さ７ナノメートルの非晶質酸化物層を有していた。原料流通開始後６ｈ目の反応成績を表５に示した。
【００９７】
実施例１５
水熱処理を、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で100時間保持して行った以外は、実施例１４と同様にして白色の焼成粉末（86.2g、触媒収率81％）を得た。この粉末はＸ線回折の結果、純粋なシャバサイト型の構造を有する８員環SAPOであり、AFI型構造体、JCPDS番号20-0045化合物のピークは見られなかった。結晶化度は良好で、1.03であった。粒子性状は、立方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、2.4μｍであった。得られた焼成粉末の結晶粒子全体のSi/Alの原子比は0.15であり、表面のSi/Alの原子比は1.98、表面のSi/Pの原子比は2.92であった。また、走査透過型電子顕微鏡観察より焼成粉末の結晶粒子は、厚さ13ナノメートルの非晶質酸化物層を有していた。原料流通開始後６ｈ目の反応成績を表５に示した。
【００９８】
実施例１６
水熱処理を、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で30時間保持して行った以外は実施例３と同様にして白色の焼成粉末（45.70g、触媒収率87％）を得た。この粉末はＸ線回折の結果、純粋なシャバサイト型構造体であり、AFI型構造体、JCPDS番号20-0045化合物のピークは見られなかった。結晶化度は1.00であった。粒子性状は、立方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、1.9μｍであった。得られた焼成粉末の結晶粒子全体のSi/Alの原子比は0.14であり、表面のSi/Alの原子比は0.65、表面のSi/Pの原子比は0.75であった。原料流通開始後６ｈ目の反応成績を表５に示した。
【００９９】
実施例１７
水熱処理を、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で20時間保持し、次いで、シリカゾル（6.1ｇ：日産化学工業株式会社，スノーテックスＮ，SiO₂含有量20wt%）を水熱処理した混合物に添加し、更に170℃で10時間第２工程の水熱処理した以外は実施例１６と同様にして白色の焼成粉末（46.21g、触媒収率88％）を得た。添加したシリカゾルのAl₂O₃に対するモル酸化物比は、SiO₂/Al₂O₃比で0.10であった。この粉末はＸ線回折の結果、純粋なシャバサイト型の構造を有する８員環SAPOであり、AFI型構造体、JCPDS番号20-0045化合物のピークは見られなかった。結晶化度は、1.00であった。粒子性状は、立方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、1.9μｍであった。得られた焼成粉末の結晶粒子全体のSi/Alの原子比は0.15であり、表面のSi/Alの原子比は2.13、表面のSi/Pの原子比は3.01であった。原料流通開始後６ｈ目の反応成績を表５に示した。この例から明らかなように、水熱処理の途中でシリカゾルを更に添加することにより、温度170℃での水熱処理時間が同じ実施例１６よりも表面のSi/Alの原子比は大きく、また、ジメチルアミン選択性が改善されていることがわかった。
【０１００】
比較例１０
水熱処理を、内容物の温度で第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で５時間保持して行った以外は、実施例１４と同様にして白色の焼成粉末（84.7g、触媒収率80％）を得た。この粉末はＸ線回折の結果、純粋なシャバサイト型構造体であり、AFI型構造体、JCPDS番号20-0045化合物のピークは見られなかった。結晶化度は0.98であった。粒子性状は、立方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、2.5μｍであった。得られた焼成粉末の結晶粒子全体のSi/Alの原子比は0.14であり、表面のSi/Alの原子比は0.49、表面のSi/Pの原子比は0.53であった。また、走査透過型電子顕微鏡観察より、焼成粉末の結晶粒子は、厚さ2.5ナノメートルの非晶質酸化物層を有していた。原料流通開始後６ｈ目の反応成績を表５に示した。
【０１０１】
比較例１１
水熱処理を、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で175時間保持して行った以外は、実施例１４と同様にして白色の焼成粉末（85.0g、触媒収率80％）を得た。この粉末はＸ線回折の結果、純粋なシャバサイト型の構造を有する８員環SAPOであり、AFI型構造体、JCPDS番号20-0045化合物のピークは見られなかった。結晶化度は1.01であった。粒子性状は、立方体状の結晶であり、大きさ、形とも良く揃っていた。平均粒子径は、2.7μｍであった。得られた焼成粉末の結晶粒子全体のSi/Alの原子比は0.14であり、表面のSi/Alの原子比は2.26、表面のSi/Pの原子比は3.13であった。また、走査透過型電子顕微鏡観察より、焼成粉末の結晶粒子は、厚さ25ナノメートルの非晶質酸化物層を有していた。原料流通開始後６ｈ目の反応成績を表５に示した。
【０１０２】
【表４】

【０１０３】
【表５】

【０１０４】
これらの例から明らかなように、本発明のシャバサイト型の構造を有する８員環SAPOは、Si/Alの原子比が、結晶粒子全体よりも大きな非晶質酸化物層を結晶粒子表面に有していることがわかった。また、メタノールとアンモニアとの反応によるメチルアミン類の製造における触媒性能は、非晶質酸化物層の厚さや、Ｘ線光電子分光法で測定される表面のSi/Alの原子比及び表面のSi/Pの原子比と相関関係があることもわかった。すなわち、非晶質酸化物層が厚くなるにつれて、また、表面のSi/Alの原子比、表面のSi/Pの原子比が大きくなるにつれて、メタノール転化率とトリメチルアミン選択率は低くなり、ジメチルアミン選択率は高くなる。メタノール転化率とジメチルアミン選択率の兼ね合いから、厚さ3〜20ナノメートルの範囲の非晶質酸化物層を有しているシャバサイト型SAPO又は、表面のSi/Alの原子比が0.50〜2.20の範囲のシャバサイトSAPO、又は、表面のSi/Pの原子比が0.55〜3.10の範囲であるシャバサイト型SAPOが優れた触媒性能を示すことがわかる。水熱処理時間の経過にともなう非晶質酸化物層の厚さ及び表面組成比の変化速度は、TEAOH/Al₂O₃のモル比やH₂O/Al₂O₃のモル比の影響を受けるが、水熱処理二段目時間が長くなるにつれて、非晶質酸化物層は厚く、表面のSi/Alの原子比、表面のSi/Pの原子比は大きくなり、メタノール転化率とトリメチルアミン選択率は低くなることがわかる。実施例１４の触媒は、反応原料の供給が空間速度（GHSV）1500h^-1、温度310℃、圧力２MPaの条件では、原料流通開始後1000時間目のメタノール転化率が95wt%で、モノメチルアミン選択率37wt%、ジメチルアミン選択率60wt%、トリメチルアミン選択率3wt%で、優れた寿命性能を示した。
【０１０５】
４． SAPO-56 と SAPO-17 における非晶質酸化物層の表面組成及び厚さと触媒性能との関係
実施例1８、１９と比較例１２は、８酸素員環細孔を有するSAPO-56とSAPO-17における非晶質酸化物層の表面組成及び厚さと触媒性能に関する例である。各実施例と比較例の結晶粒子全体のSi/Alの原子比（バルクSi/Alの原子比）、表面のSi/Alの原子比、表面のSi/Pの原子比、非晶質酸化物層の厚さを表６にまとめた。反応試験は、実施例１〜９と同様にして行った。
【０１０６】
実施例１８
85％リン酸（75.6g）と純水（256.6g）及び、Ｎ，Ｎ，Ｎ’，Ｎ’−テトラメチル−１，６−ヘキサンジアミン（113.0g）の均一な混合物に、擬ベーマイト（43.1g：SASOL GERMANY GmbH，PURAL NF，Al₂O₃含有量77.5%）を撹拌しながら添加した。この混合物を１時間撹拌した後、ヒュームドシリカ（11.8g：日本アエロジル株式会社，AEROSIL-200）を添加し、更に30分間撹拌した。この混合物のモル酸化物比における組成は次の通りであった：2.0TMHD：1.0Al₂O₃：1.0P₂O₅：0.6SiO₂：50H₂O（TMHDはＮ，Ｎ，Ｎ’，Ｎ’−テトラメチル−１，６−ヘキサンジアミンを表す）。得られた混合物をステンレス製オートクレーブ中で撹拌しながら、水熱処理した。水熱処理は、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で75時間保持して行った。水熱処理時の圧力は自生圧とした。室温まで冷却した後、オートクレーブを開け、生成スラリーを遠心分離して沈殿を得た。得られた沈殿を200mlの純水で３回、洗浄・遠心分離したのち、80℃で12ｈ乾燥した。更に空気気流下、600℃で４時間焼成して、白色粉末を得た。この粉末はＸ線回折の結果、純粋な８酸素員環細孔を有するSAPO-56であった。この焼成粉末の結晶粒子全体のSi/Alの原子比は0.27であり、表面のSi/Alの原子比は1.75、表面のSi/Pの原子比は2.71であった。また、走査透過型電子顕微鏡観察より、焼成粉末の結晶粒子は、10ナノメートルの厚さの非晶質酸化物層を持っていた。原料流通開始後６ｈ目の反応成績を表６に示した。
【０１０７】
実施例１９
85％リン酸（52.0g）と純水（176.6g）及び、キヌクリジン（37.6g）の均一な混合物に、擬ベーマイト（29.7g：SASOL GERMANY GmbH，PURAL NF，Al₂O₃含有量77.5%）を撹拌しながら添加した。この混合物を１時間撹拌した後、ヒュームドシリカ（4.1g：日本アエロジル株式会社，AEROSIL-200）を添加し、更に30分間撹拌した。この混合物のモル酸化物比における組成は次の通りであった：1.5Qn：1.0Al₂O₃：1.0P₂O₅：0.3SiO₂：50H₂O（Qnはキヌクリジンを表す）。得られた混合物をステンレス製オートクレーブ中で撹拌しながら、水熱処理した。水熱処理は、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で50時間保持して行った。水熱処理時の圧力は自生圧とした。室温まで冷却した後、オートクレーブを開け、生成スラリーを遠心分離して沈殿を得た。得られた沈殿を200mlの純水で３回、洗浄・遠心分離したのち、80℃で12ｈ乾燥した。更に空気気流下、600℃で４時間焼成して、白色粉末を得た。この粉末はＸ線回折の結果、純粋な８酸素員環細孔を有するSAPO-17であった。この焼成粉末の結晶粒子全体のSi/Alの原子比は0.11であり、表面のSi/Alの原子比は1.01、表面のSi/Pの原子比は1.36であった。また、走査透過型電子顕微鏡観察より、焼成粉末の結晶粒子は、５ナノメートルの厚さの非晶質酸化物層を持っていた。原料流通開始後６ｈ目の反応成績を表６に示した。
【０１０８】
比較例１２
水熱処理を、内容物の温度で、第１工程として25℃から115℃までを20℃/ｈで昇温し、115℃で５時間保持したのち、115℃から170℃までを20℃/ｈで昇温し、第１工程の結晶化工程の一部と第２工程として170℃で５時間保持して行った以外は、実施例１８と同様にして白色の焼成粉末を得た。この粉末はＸ線回折の結果、純粋な８酸素員環細孔を有するSAPO-56であった。この焼成粉末の結晶粒子全体のSi/Alの原子比は0.25であり、表面のSi/Alの原子比は0.48、表面のSi/Pの原子比は0.51であった。また、走査透過型電子顕微鏡観察より、焼成粉末の結晶粒子は、２ナノメートルの厚さの非晶質酸化物層を持っていた。原料流通開始後６ｈ目の反応成績を表６に示した。
【０１０９】
これらの例から明らかなように、シャバサイト型以外の構造を有する８員環SAPOでも、本発明の、Si/Alの原子比が結晶粒子全体よりも大きな非晶質酸化物層を、結晶粒子表面に有していることがわかる。また、好ましい範囲の厚さの非晶質酸化物層又は好ましい範囲の表面組成比を有するこれらの８員環SAPOは、メタノールとアンモニアとの反応によるメチルアミン類の製造において、優れた触媒活性とジメチルアミン選択性を示すこともわかる。
【０１１０】
【表６】

【０１１１】
５．モノメチルアミンを原料とした不均化反応例
実施例２０と比較例１３は、モノメチルアミンを原料とした不均化反応の例である。
【０１１２】
実施例２０
反応管に実施例６で合成した触媒2.5ｇ（体積3.5ｍｌ）を充填し、反応圧力2MPa、温度320℃において、モノメチルアミンをGHSV3000h^-1で供給して反応を行った。モノメチルアミンからアンモニアとジメチルアミンへの不均化反応の反応開始６時間目における成績は、以下の通りであった。
モノメチルアミンの転化率：73モル％
ジメチルアミン選択率：99重量％
トリメチルアミン選択率：1重量％
【０１１３】
比較例１３
比較例８で合成した触媒を用いて、実施例２０と同様にモノメチルアミンの不均化反応を行った。反応開始６時間目における成績は、以下の通りであった。
モノメチルアミンの転化率：69モル％
ジメチルアミン選択率：98重量％
トリメチルアミン選択率：2重量％
【０１１４】
特開2000-117114号公報記載の触媒調製例１の方法に従って合成した比較例８の触媒を用いた比較例１３の結果と比べ、実施例６のシャバサイト型の構造を有する８員環SAPOは実施例２０に示すように、モノメチルアミンの不均化反応においても優れた性能を示すことがわかった。
【０１１５】
【発明の効果】
以上の実施例、比較例を用いた説明から明らかな様に、本発明の８員環SAPOは、アルミニウムに対するケイ素の原子比が、結晶粒子全体よりも大きな非晶質酸化物層を結晶粒子表面に有しており、該モレキュラーシーブは、工業的に行われているメタノールとアンモニアとの反応、モノメチルアミンの不均化反応等によるメチルアミン類の製造において、従来技術よりも優れた触媒活性とジメチルアミン選択性を示す。この非晶質酸化物層の厚さや表面組成は、触媒性能に大きな影響を及ぼすが、本発明の触媒の合成条件で容易に制御できる。また、本発明の８員環SAPOの製造法によれば、従来合成が困難であった少量の鋳型剤量で、純度及び結晶化度が高い８員環SAPOを製造することができる。そのため、従来技術よりも原材料コスト、廃棄物処理コストともに低減できるため、安価に効率良く触媒が製造できる。また、廃棄物が少ないため、環境に対する負荷の低減の面でも貢献できる。従って、本発明の提供する８酸素員環細孔を持つ結晶質シリコアルミノリン酸塩モレキュラーシーブとその製造法及びメチルアミン類の製造方法の工業的価値は極めて大きい。
【図面の簡単な説明】
【図１】実施例１４の触媒の走査透過型電子顕微鏡による像（×８万倍）
【図２】図１の左端白枠部分の拡大像（×100万倍）
【図３】図２の格子模様が見られる部分の電子線回折像
【図４】図２の格子模様が見られない白色層の電子線回折像[0001]
BACKGROUND OF THE INVENTION
The present invention catalyzes a crystalline silicoaluminophosphate molecular sieve having eight oxygen-membered ring pores (hereinafter referred to as “8-membered ring SAPO” in principle), a production method thereof, and an eight-membered ring SAPO obtained by the method. The present invention relates to a method for producing methylamines to be used as
More specifically, it is an 8-membered ring SAPO having an amorphous oxide layer on the crystal particle surface that greatly affects the catalyst performance, and the atomic ratio of silicon (Si / Al) to aluminum in the amorphous oxide layer is The present invention relates to an 8-membered ring SAPO and a method for producing the same, and a method for producing methylamines using the 8-membered ring SAPO obtained by the method as a catalyst. Shabasite-type crystalline silicoaluminophosphate molecular sieve contains silicon, aluminum, phosphorus, and oxygen having a structure of CHA type expressed by the IUPAC structure code defined by International Zeolite Association (IZA). It is one of the 8-membered ring SAPOs as the main component.
Methylamines, particularly dimethylamine, are important as raw materials for solvents, rubber products, pharmaceuticals, surfactants and the like typified by dimethylformamide.
[0002]
[Prior art]
Methylamines are usually produced from methanol and ammonia at a temperature of around 400 ° C. using a solid acid catalyst such as silica-alumina. As is well known, when the silica-alumina catalyst is used, the product follows a thermodynamic equilibrium, and trimethylamine, which is the least in demand among the three kinds of methylamines of mono, di, and tri, is mainly produced. It becomes a thing. However, since most of the demand for methylamines is biased toward dimethylamine, in recent years, development of a selective method for producing dimethylamine exceeding the thermodynamic equilibrium composition has been promoted.
[0003]
As such a method, for example, zeolite A (for example, see Patent Document 1), FU-1 (for example, see Patent Document 2), ZSM-5 (for example, see Patent Document 3), ferrierite and erionite (for example, , ZK-5, Rho, shabasite and erionite (for example, see Patent Document 5), mordenite (for example, see Patent Documents 6, 7, 8, and 9) and the like (crystalline aluminosilicate) And a method using a salt molecular sieve).
In these methods, zeolites with a small pore inlet diameter are further subjected to ion exchange, dealumination treatment, addition of a specific element or silylation treatment, etc., to control the pore inlet diameter or to adjust the outer surface acidic point. By modifying it, dimethylamine selectivity and catalytic activity are improved.
[0004]
In addition, a method for producing monomethylamine or the like exceeding the thermodynamic equilibrium composition using crystalline silicoaluminophosphate molecular sieve (hereinafter, referred to as SAPO in principle), which is a non-zeolite molecular sieve (for example, Patent Document 10) See also).
As a result of repeated studies on selective dimethylamine production technology, the present inventors have found that silica-modified SAPO and SAPO modified with various oxides are more active and higher than the prior art using zeolite catalysts. It has been found that it exhibits dimethylamine selectivity and has already been filed (see Patent Documents 11, 12, and 13).
[0005]
Generally, it is considered that the surface of a crystalline molecular sieve such as zeolite or SAPO is exposed. Therefore, the surface of zeolite and SAPO has a strong acidic point that is a characteristic of molecular sieves containing silicon and aluminum. Surface acidic point treatment such as liquid phase silylation treatment or modification with a compound containing boron or phosphorus is often performed (see, for example, Patent Documents 14, 15, 16, 17, and 18). Moreover, the technique of the gazettes of the present inventors (see Patent Documents 11, 12, and 13) is also based on this concept.
[0006]
However, these conventionally known methods involve a large number of steps because they are methods for further modification of the catalyst after the synthesis of SAPO, followed by separation and washing by centrifugation or filtration, and in some cases, the calcined catalyst. In particular, in the silylation treatment, it is necessary to precisely control the water content of the catalyst to be treated, and an organic solvent such as ethanol or toluene is used, which causes a problem of waste liquid treatment.
Thus, the conventionally known method for improving the activity and selectivity by further modifying the synthesized SAPO has problems to be improved concerning both the economy and the environment. It is desired to develop a new method for controlling selectivity, which is different from a method that requires a conventional post-treatment process.
[0007]
In response to such a problem, the present inventors have already made a shabasite type of SAPO whose average particle diameter is 5 μm or less and whose crystal shape is a rectangular parallelepiped or a cube, in addition to the technique described above. It has been found and filed that 8-membered SAPO exhibits excellent catalytic activity and dimethylamine selectivity as a production catalyst for methylamines (see Patent Document 19).
This shabasite-type 8-membered ring SAPO showed excellent activity and selectivity without modification after synthesis, but in further investigation by the present inventors, there were differences in the catalyst performance depending on the synthesis lot. There was a phenomenon of being recognized, and there was a problem that further technical improvement was required in order to stably obtain the best catalyst.
[0008]
Further, the shabasite-type 8-membered ring SAPO having the above particle size and shape is composed of organic amines or organic ammonium salts such as diethanolamine and tetraethylammonium hydroxide, Al₂O_ThreeThese compounds are synthesized using 1.5 ± 0.5 times the moles of aluminum compound converted to, but these organics incorporated into the as-synthesized shabasite-type 8-membered ring SAPO before firing. The amount of amines or organic ammonium salt is Al₂O_ThreeIt is about 0.37 times the amount necessary for constructing a crystal structure with respect to the number of moles. Therefore, organic amines or organic ammonium salts that are not taken into the crystal structure become surplus and need to be treated with activated sludge or the like. Accordingly, if a pure 8-membered ring SAPO can be synthesized by reducing the amount of organic amines or organic ammonium salts used, it can be an excellent method in both economic and environmental aspects.
[0009]
Since 8-membered SAPO shows relatively high dimethylamine selectivity in methylamine synthesis reaction, many studies have been conducted on methylamine synthesis reaction using these SAPOs (for example, non-patents). Reference 4). As the 8-membered ring SAPO, SAPO-14, 17, 18, 33, 34, 35, 39, 42, 43, 44, 47, 56 are known (for example, see Non-Patent Document 5 and Non-Patent Document 6). ). Among them, three types of shabasite type 8-membered SAPOs are known, SAPO-34, SAPO-44, and SAPO-47. Among them, shabasite type structure SAPO-34 is a methylamine synthesis reaction and methanol conversion. It has been well studied as a catalyst for the reaction (see, for example, Patent Documents 10 and 21).
[0010]
These 8-membered ring SAPOs conventionally use a compound such as tetraethylammonium hydroxide, morpholine, cyclohexylamine, and diethylethanolamine as a template agent, and hydrothermally treat a mixture of silicon compound, aluminum compound, phosphorus compound, and water. It is known that they can be synthesized (see, for example, Patent Document 20). However, such an 8-membered ring SAPO has an amorphous oxide layer on the crystal particle surface, the amorphous oxide layer grows on the crystal particle surface during hydrothermal synthesis, and It is not known that it greatly affects the yield and selectivity of the methylamine synthesis reaction.
[0011]
Normally, when synthesizing 8-membered ring SAPO, the mixture to be hydrothermally treated is represented by the composition formula shown in the following formula (1), and the amount of the templating agent R used is the Al₂O_ThreeIn general, it is used in an amount of 1 to 3 times the number of moles (a / c = 1 to 3).
aR, bSiO₂, CAl₂O_Three, DP₂O_Five, EH₂O ··· Formula (1)
[0012]
As a result of examining various patents and literatures regarding the amount of the templating agent used in the synthesis of 8-membered ring SAPO, the templating agent was obtained in order to obtain a pure and highly crystallized shabasite type 8-membered SAPO. Is at least Al in the mixture to be hydrothermally treated₂O_ThreeWhen the amount is more than 1 times the number of moles, and less than that, it is represented by the IUPAC structure code defined by the International Zeolite Association (IZA) and is a structure belonging to the AFI type (SAPO-5) And aluminum phosphate cristobalite, berlinite, etc. are said to be present as impurities.
[0013]
There is a document describing a method for synthesizing SAPO-34 using tetraethylammonium hydroxide (TEAOH) as a templating agent (see, for example, Non-Patent Document 1). Pure SAPO-34 is TEAOH / Al.₂O_ThreeIn the range of 1-2, SAPO-5 is produced in the range of 1 to 2, and in the range of 1 or less, the high density phase is produced. It is described that when three or more TEAOHs are used, particles having an amorphous amorphous structure are generated.
Further, there is a document describing a method for synthesizing SAPO-34 using morpholine as a templating agent (see, for example, Non-Patent Document 2), and morpholine / Al₂O_ThreeWhen the molar ratio is 0.5 or less, it becomes a mixture of aluminum phosphate cristobalite and amorphous compound, and morpholine / Al₂O_ThreeA molar ratio of 1.0 yields a mixture of 80% SAPO-34 and 20% cristobalite, pure SAPO-34 being morpholine / Al₂O_ThreeIt is described that the molar ratio is 2.0 or more.
Furthermore, there is a document describing a method for synthesizing SAPO-44 using cyclohexylamine as a templating agent (see, for example, Non-Patent Document 3), and cyclohexylamine / Al₂O_ThreeIt is described that SAPO-5 is mixed at a molar ratio of 1.9 or less.
[0014]
[Patent Document 1]
JP-A-56-69846
[Patent Document 2]
JP 54-148708 A
[Patent Document 3]
U.S. Pat. No. 4,082,805
[Patent Document 4]
Japanese Patent Application Laid-Open No. 56-113747
[Patent Document 5]
JP-A-61-254256
[Patent Document 6]
JP-A-56-46846,
[Patent Document 7]
JP 58-49340 A
[Patent Document 8]
JP 59-2105050 A
[Patent Document 9]
JP 59-227841 A
[Patent Document 10]
JP-A-2-734
[Patent Document 11]
Japanese Patent Laid-Open No. 11-35527
[Patent Document 12]
JP-A-11-239729,
[Patent Document 13]
Japanese Patent Laid-Open No. 2000-5604
[Patent Document 14]
JP-A-3-262540
[Patent Document 15]
Japanese National Patent Publication No. 11-508901
[Patent Document 16]
JP-A-6-179640,
[Patent Document 17]
Japanese Patent Laid-Open No. 7-2740
[Patent Document 18]
JP-A-61-254256
[Patent Document 19]
JP 2000-117114 A
[Patent Document 20]
U.S. Pat. No. 4,440,871
[Patent Document 21]
US Pat. No. 5,126,308
[Non-Patent Document 1]
J. Liang, H. Li, S. Zhao, W. Guo, R. Wang, and M. Ying, Appl. Catal., 1991, 64, p.31-p.40
[Non-Patent Document 2]
A. M. Prakash, S. Unnikrishnan, J. Chem. Soc. Faraday Trans., 1994, 90 (15), p.2291-p.2296
[Non-Patent Document 3]
S. Ashtekar, S. V. V. Chilukuri, D. K. Chakrabarty, J. Phys. Chem. 1994, 98, p.4878-p.4883
[Non-Patent Document 4]
D. R. Corbin, S. Schwarz, and G. C. Sonnichsen, Catalysis Today, 1997, 37, p.71-p.102.
[Non-Patent Document 5]
E. M. Flanigen, B. M. Lok, R. L. Patton, and S. T. Wilson, New Developments in Zeolite Science and Technology, Elsevier, 1986, p.103-p.112.
[Non-Patent Document 6]
Structure Commission of the International Zeolite Association, Atlas of Zeolite Framework Types, Elsevier, 2001, p.14-p.15.
[0015]
[Problems to be solved by the invention]
As described above, the present inventors have modified the post-synthesis modification of a SAPBAO-type 8-membered ring SAPO having an average crystal particle size of 5 μm or less and a crystal shape of a rectangular parallelepiped or a cube. It has been found that it exhibits excellent catalytic activity and dimethylamine selectivity as a production catalyst for methylamines even if it is not carried out (Japanese Patent Laid-Open No. 2000-117114). However, even with the above particle diameter and shape, there may be a difference in catalyst performance depending on the lot.
[0016]
In addition, the shabasite-type 8-membered ring SAPO has an amount of organic amines or organic ammonium salts such as tetraethylammonium hydroxide (TEAOH) and diethanolamine used as Al.₂O_ThreeIt can be obtained by hydrothermal treatment of a raw material mixture in the range of 1.5 ± 0.5 times the number of moles of aluminum compound converted to, but requires an excess of organic amines or organic ammonium salts as listed here In this method, the yield of the resulting catalyst is low, and an excess amount of organic amines or organic ammonium salts must be treated with activated sludge or the like.
As described above, SAPO described in Japanese Patent Application Laid-Open No. 2000-117114 left problems to be further improved such as stability as an amine synthesis catalyst and problems associated with excessive use of a templating agent.
[0017]
That is, the object of the present invention is to solve the above-mentioned problems and to provide an 8-membered ring SAPO having excellent catalytic activity and dimethylamine selectivity, its inexpensive and stable production method, and methylamines using the catalyst. It is to provide a manufacturing method.
[0018]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have made silicon (Si) larger than the crystalline portion around the crystalline molecular sieve particle body in the process of synthesizing the 8-membered ring SAPO. An amorphous oxide layer having an atomic ratio of (/ Al) is formed, and an 8-membered ring SAPO in which the atomic ratio of Si / Al in the amorphous oxide layer is larger than the atomic ratio of the entire crystal grain is obtained. The atomic ratio or thickness of Si / Al in the amorphous oxide layer greatly affects the catalytic activity and dimethylamine selectivity, and the hydrothermal treatment temperature in the process of forming the amorphous oxide layer We found that it can be controlled precisely with time. It has been found that by controlling the Si / Al atomic ratio or thickness of the amorphous oxide layer, a catalyst having stable catalytic activity and dimethylamine selectivity can be produced.
[0019]
In addition, as a condition for hydrothermal treatment, first, hydrothermal treatment is performed for 1 hour or more in a temperature range between 80 ° C. and 130 ° C., and then hydrothermal treatment is performed in a temperature range of 150 to 200 ° C. for 1 to 10 hours ( The amount of organic amines and organic ammonium salts that are templating agents can be reduced by performing a treatment that includes a hydrothermal treatment step (second step) for 10 hours or more within a temperature range of 150 to 200 ° C. Al₂O_ThreeOn the other hand, it was found that even when the molar ratio was reduced to less than 1.0 times, a high crystallinity, a pure 8-membered ring SAPO was obtained, and the catalyst yield was improved as compared with the conventional production method.
[0020]
Further, the 8-membered ring SAPO thus obtained was found to have superior catalytic activity and dimethylamine selectivity over the shabasite-type SAPO obtained by the conventional production method. Established a method for stably producing a catalyst with excellent activity and dimethylamine selectivity by combining production technology with technology that controls the atomic ratio or thickness of Si / Al in the amorphous oxide layer. The present invention has been completed.
[0021]
That is, according to the present invention, there is provided an eight-membered ring SAPO having an amorphous oxide layer having a Si / Al atomic ratio larger than that of the entire crystal grain on the crystal grain surface, and the amorphous oxide layer. The present invention relates to a method for producing an 8-membered ring SAPO, characterized in that the thickness or the surface composition of crystal grains is precisely controlled by the temperature and time of hydrothermal treatment in the process of forming an amorphous oxide layer. In addition, when a raw material mixture containing an organic amine and / or organic ammonium salt as an templating agent and an aluminum compound, a phosphorus compound, a silicon compound, and water is hydrothermally treated to produce an 8-membered ring SAPO, Al₂O_ThreeThe ratio of the total number of moles of the organic amine and the organic ammonium salt to the number of moles of the aluminum compound converted to is in the range of 0.4 to 0.98, and the raw material mixture is in the temperature range of 80 to 130 ° C. as the first step. Hydrothermal treatment at 1 to 10 hours after hydrothermal treatment at 150 to 200 ° C., followed by hydrothermal treatment at 150 to 200 ° C. for 10 hours or more as the second step It is related with the manufacturing method of 8-membered ring SAPO characterized by performing. Further, the present invention relates to a method for producing methylamines using, as a catalyst, 8-membered SAPO produced by combining these 8-membered SAPO production techniques.
[0022]
More specifically, the present invention relates to the 8-membered SAPO shown in the following (1) to (24) and a production method thereof, and a production method of methylamines using the same as a catalyst.
(1) An 8-membered ring SAPO having an amorphous oxide layer on the crystal grain surface, wherein the atomic ratio of silicon to aluminum in the amorphous oxide layer is larger than the atomic ratio of the entire crystal grain Eight-membered ring SAPO characterized by this.
(2) The atomic ratio of silicon to aluminum in the entire crystal grain is in the range of 0.05 to 0.30, and the atomic ratio of silicon to aluminum in the amorphous oxide layer on the crystal grain surface measured by X-ray photoelectron spectroscopy is The 8-membered ring SAPO according to (1), which is 0.50 or more.
(3) The 8-membered member according to any one of (1) and (2), wherein the atomic ratio of silicon to phosphorus in the amorphous oxide layer on the crystal particle surface measured by X-ray photoelectron spectroscopy is 0.55 or more Ring SAPO.
(4) The 8-membered ring SAPO according to any one of (1) to (3), wherein the thickness of the amorphous oxide layer on the crystal particle surface is in the range of 3 to 20 nanometers.
(5) The 8-membered ring SAPO according to any one of (1) to (4), further including one or more elements selected from magnesium, yttrium, titanium, zirconium, manganese, iron, cobalt, and tin.
(6) The 8-membered ring SAPO according to any one of (1) to (5), wherein the crystal particles have a rectangular parallelepiped shape and / or a cubic shape, and an average particle diameter of 5 μm or less.
(7) The eight-membered ring according to any one of (1) to (6), wherein the structure of the main part of the crystal grain excluding the amorphous oxide layer on the crystal grain surface from the whole crystal grain is a shabasite type Pore SAPO.
(8) The ratio of the peak intensity of the (100) plane of the AFI structure to the peak intensity of the (100) plane of the shabasite structure measured by X-ray diffraction is 0.02 or less. Type 8-membered ring SAPO.
(9) A raw material mixture containing an organic amine and / or an organic ammonium salt, an aluminum compound, a phosphorus compound, a silicon compound, and water is hydrothermally treated to form an 8-membered ring SAPO having an amorphous oxide layer on the crystal particle surface. (1) to (8) comprising a first step of producing at least a crystalline portion thereof and a second step of further performing a hydrothermal treatment to form an amorphous oxide layer on the crystal particle surface. 8) The method for producing an 8-membered ring SAPO according to any one of the above.
(10) The hydrothermal treatment of the first step includes two steps: a hydrothermal treatment for 1 hour or more within a temperature range of 80 to 130 ° C. and a hydrothermal treatment for 1 to 10 hours within a temperature range of 150 to 200 ° C. The manufacturing method of the 8-membered ring SAPO of Claim 9 which is what is contained.
(11) Of the hydrothermal treatment of the first step, the step of hydrothermal treatment for 1 hour or more within a temperature range of 80 to 130 ° C. is a step of raising the temperature between 80 to 130 ° C. over 1 hour or 80 to 130 The method for producing an 8-membered ring SAPO according to (10), which comprises a step of maintaining a constant temperature between 1 ° C. and 1 hour or more.
(12) The production of the 8-membered ring SAPO according to any one of (9) to (11), wherein the hydrothermal treatment in the second step includes a hydrothermal treatment for 10 hours or more within a temperature range of 150 to 200 ° C. Method.
(13) The hydrothermal treatment in the first step includes two steps: a hydrothermal treatment for 3 to 24 hours at a constant temperature of 95 to 125 ° C, and a hydrothermal treatment for 1 to 10 hours within a temperature range of 150 to 200 ° C. The method for producing an 8-membered ring SAPO according to (9), which comprises a step, and the hydrothermal treatment in the second step comprises a hydrothermal treatment in a temperature range of 150 to 200 ° C. for 10 to 150 hours.
(14) Al in a raw material mixture containing organic amine and / or organic ammonium salt, aluminum compound, phosphorus compound, silicon compound, and water₂O_ThreeThe ratio of the total number of moles of the organic amine and the organic ammonium salt to the number of moles of the aluminum compound converted to is in the range of 0.4 to 0.98, and the 8-membered SAPO according to any one of (9) to (13) Production method.
(15) The method for producing an 8-membered ring SAPO according to any one of (9) to (14), wherein the organic amine and / or the organic ammonium salt is tetraethylammonium hydroxide.
(16) The method for producing an 8-membered ring SAPO according to any one of (9) to (15), wherein the aluminum compound is pseudoboehmite.
(17) The method for producing an 8-membered ring SAPO according to any one of (9) to (16), wherein the phosphorus compound is phosphoric acid.
(18) The method for producing an 8-membered ring SAPO according to any one of (1) to (17), wherein the silicon compound is silica sol.
(19) The method for producing an 8-membered ring SAPO according to any one of (1) to (18), wherein a silicon compound is further added before or during the second step.
(20) The 8-membered ring SAPO according to any one of (9) to (19), further including one or more elements selected from magnesium, yttrium, titanium, zirconium, manganese, iron, cobalt, and tin Production method.
(21) The method for producing an 8-membered ring SAPO according to (9) to (20), wherein the 8-membered ring SAPO is a shabasite type.
(22) A process for producing methylamines, wherein methanol and ammonia are reacted in the presence of the 8-membered ring SAPO according to any one of (1) to (8).
(23) A method for producing methylamines, wherein methanol and monomethylamine are reacted in the presence of the 8-membered ring SAPO according to any one of (1) to (8).
(24) A method for producing methylamines, wherein a monomethylamine is disproportionated in the presence of the 8-membered ring SAPO according to any one of (1) to (8).
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail. SAPO in the present invention is an 8-membered ring SAPO having an amorphous oxide layer on the surface in which the atomic ratio of Si / Al is larger than the whole crystal grains.
SAPO is crystalline and microporous as described in U.S. Pat.No. 4,440,871.₂ ⁺, AlO₂ ^-And SiO₂It is a compound having a three-dimensional microporous crystal skeleton structure composed of tetrahedral units.
A compound containing a tetrahedral unit of a metal other than silicon, aluminum, and phosphorus in a three-dimensional microporous crystal skeleton structure is also disclosed in European Patent No. 159,624 and is called ELAPSO molecular sieve. However, these patent publications do not describe SAPO having an amorphous oxide layer on its surface as in the present invention.
[0024]
The 8-membered ring SAPO of the present invention may contain a metal component other than silicon, aluminum, and phosphorus. A case where an element selected from magnesium, yttrium, titanium, zirconium, manganese, iron, cobalt and tin is included is preferable, and titanium and zirconium are particularly preferable because they have an effect of improving catalyst activity and life performance. These element components may exist outside the three-dimensional microporous crystal skeleton structure and / or the skeleton structure. The content of these elements is not particularly limited, but the atomic ratio when these elements are combined with aluminum is preferably in the range of 0.0001 to 0.1. Eight-membered ring SAPO containing these elements includes templating agents, silicon compounds, aluminum compounds, phosphorus compounds, water, and nitrates, sulfates, chlorides, oxide sols, oxide powders, alkoxides and / or complexes of the above elements. This mixture can be synthesized by hydrothermal treatment.
[0025]
In order to selectively obtain methylamines, particularly dimethylamine in the reaction of methanol and ammonia, it is desirable that the effective pore diameter of SAPO is in the range of 0.3 to 0.6 nanometer. Such pores block the passage of trimethylamine molecules and allow smaller molecular sizes of monomethylamine and dimethylamine to pass, so ultimately the selectivity of the reaction is offset by monomethylamine and dimethylamine (DR Corbin, S. Schwarz, and GC Sonnichsen, Catalysis Today, 37 (1997), p.71-p.102). The effective pore diameter corresponds to the pore diameter of the 8-10 oxygen member ring of SAPO, and among them, the 8-membered SAPO is necessary for lowering the selectivity of trimethylamine.
[0026]
Examples of the 8-membered ring SAPO include SAPO-14, 17, 18, 33, 34, 35, 39, 42, 43, 44, 47 and 56. The relationship between the number assigned to each SAPO and the IUPAC structure code established by the International Zeolite Association (IZA) Structure Commission is, for example, “Atlas of Zeolite Framework Types” edited by the Structure Commission of the International Zeolite Association. Issued. The SAPO IUPAC structure codes correspond to AFN, ERI, AEI, ATT, CHA, LEV, ATN, LTA, GIS, CHA, CHA, and AFX, respectively. Among the SAPOs, SAPO-17, 18, 34, 35, 44, 47 and 56 are preferable, and SAPO-34 having a shabasite structure is particularly preferable.
[0027]
The shabasite-type 8-membered ring SAPO in the present invention is a silicon, aluminum, phosphorus, and oxygen having a CHA type structure expressed by the IUPAC structure code defined by the International Zeolite Association (IZA) described above. It is a crystalline molecular sieve whose main component is. Specifically, among the SAPOs described in US Pat. No. 4,440,871, the compound has a structure represented by the CHA type. SAPO with such a CHA-type structure can be found in the literature EM Flanigen, RL Patton, and ST Wilson, Studies in Surface Science and Catalysis, Innovation in Zeolite Materials Science, p.13-p.27 (1988). In addition, three types of SAPO-34, SAPO-44, and SAPO-47 are known.
[0028]
The greatest feature of the 8-membered ring SAPO of the present invention is that the surface has an amorphous oxide layer having an atomic ratio larger than the Si / Al atomic ratio of the entire crystal grain. This amorphous oxide layer can be observed by FIB-STEM analysis. Figures 1 and 2 are examples of SAPO-34, which is obtained by cutting both sides of a cubic SAPO-34 particle with a focused ion beam (FIB: Focused Ion Beam, Hitachi FB-2100). The cross section of the remaining 80-nm-thick slice was observed with a scanning transmission electron microscope (STEM: Scanning Transmission Electron Microscope, HD-2000 thin film evaluation apparatus manufactured by Hitachi, Ltd.). Although a three-layer structure can be seen in FIG. 1, the outermost layer is a layer of carbon, platinum, and tungsten deposited to fix the sample particles and increase conductivity. The central part is the crystal grain body, and the thin layer between them is an amorphous oxide layer. FIG. 2 is an enlarged view of a portion of about 100 nanometers from the surface of FIG. The portion with the lattice pattern corresponds to the crystal grain main body excluding the amorphous oxide layer, and the white layer without the lattice pattern corresponds to the amorphous oxide layer. The lattice pattern means a regular structure, and clear Laue spots were observed by electron diffraction, indicating that the crystal grain main body is crystalline (FIG. 3). On the other hand, the white layer in which the lattice pattern is not observed has no regular structure because it cannot observe Laue spots by electron diffraction, and is amorphous (FIG. 4). In addition, the composition of the energy dispersive X-ray analyzer (EDX: Energy Dispersive X-Ray Analysis) indicates that the amorphous layer has a larger Si / Al atomic ratio than the crystal particle body and is rich in silicon components. It was confirmed that this was an oxide layer.
[0029]
The presence and thickness of the amorphous oxide layer have a great influence on the reaction activity and dimethylamine selectivity in the production of methylamines by the reaction of methanol and ammonia or the disproportionation reaction of monomethylamine. Taking SAPO-34 as an example, in the reaction using SAPO-34 with an amorphous oxide layer thinner than 3 nanometers, although the reaction activity is high, trimethylamine is generated with a selectivity of 10% or more. The selectivity for dimethylamine is poor. On the other hand, if the amorphous oxide layer exceeds 20 nanometers, the trimethylamine selectivity is as low as 1% or less, but the reaction activity is low. These results show that when the amorphous oxide layer is thin, the active acid sites on the surface of the crystal particles that do not show the molecular sieving effect are not sufficiently covered, and the remaining active acid sites are the most thermodynamically. The formation of stable trimethylamine, on the other hand, in the case of an amorphous oxide layer that is too thick, the coverage of the active acid point proceeds sufficiently, but the diffusion of the reactant to the active crystal body and the crystal body of the generated material This can be explained by considering that the reaction activity decreases due to slow release from the reaction. The amorphous oxide layer is mainly composed of oxides of silicon, aluminum and phosphorus, and since silicon is the main component, it does not have strong acid properties like silica-alumina and has almost no reaction activity. .
That is, the preferable thickness of the amorphous oxide layer in the present invention is 3 to 20 nanometers, and more preferably 3.5 to 16 nanometers.
[0030]
The composition of the amorphous oxide layer can be analyzed by the energy dispersive X-ray analyzer, but can be more easily measured by analyzing the surface composition of crystal grains using X-ray photoelectron spectroscopy (XPS, ESCA). . In X-ray photoelectron spectroscopy, the composition in the range from the outermost surface of the crystal particles to a depth of 1.5 to 4.0 nanometers is measured.
On the other hand, the composition of the crystal particle body can be regarded as almost the same as the composition of the entire crystal particle because the amorphous oxide layer is very thin. For example, the SAPO particles are completely dissolved with mineral acid, etc. It can be measured by coupled plasma emission spectroscopy (ICP).
[0031]
The surface composition in the present invention is measured using an ESCALAB MKII apparatus manufactured by VG Scientific Ltd. and using an Al-Kα ray (1486.7 eV) as an X-ray source, and the document JH Scofield, Journal of Electron Spectroscopy and Related. Phenomena, 8 (1976) p.129-p.137. The composition of the entire crystal particles was measured with an SPS-1200VR apparatus manufactured by Seiko Instruments Inc. after dissolving SAPO in a solution containing low concentration hydrofluoric acid.
The surface composition of crystal grains measured by X-ray photoelectron spectroscopy varies with the thickness of the amorphous oxide layer. The atomic ratio of Si / Al and the atomic ratio of Si / P are the thickness of the amorphous oxide layer. It increases with the height. For example, in the case of SAPO-34, when the thickness of the amorphous oxide layer is 2.5 nanometers, the atomic ratio of Si / Al by X-ray photoelectron spectroscopy is 0.49, and the atomic ratio of Si / P is 0.53. When the amorphous oxide layer thickness is 7 nanometers, the Si / Al atomic ratio is 1.61, the Si / P atomic ratio is 2.45, and the amorphous oxide layer thickness is 13 nanometers. The atomic ratio of Si / Al is 1.98, and the atomic ratio of Si / P is 2.92.
As described above, the Si / Al atomic ratio and the Si / P atomic ratio increase as the thickness of the amorphous oxide layer increases. This is because, among the silicon, aluminum, and phosphorus components present in the mother liquor, the silicon components are selectively deposited on the crystal particle surfaces. This can be seen from the ICP analysis of the synthetic mother liquor in the process of forming the amorphous oxide layer, in which the silicon component in the mother liquor is selectively reduced.
[0032]
That is, the surface composition of the crystal particles corresponds to the thickness of the amorphous oxide layer. The atomic ratio of Si / Al on the 8-membered ring SAPO surface exhibiting excellent reaction activity and dimethylamine selectivity is in the range of 0.50 to 2.20 when no silicon compound is added in the second step described later. Similarly, the atomic ratio of Si / P ranges from 0.55 to 3.10. When a silicon compound is added in the second step, the concentration of the silicon component in the synthetic mother liquor is considerably higher than the concentrations of aluminum and phosphorus, so the Si / Al atomic ratio on the 8-membered SAPO surface, which exhibits excellent performance, The atomic ratio of Si / P is 0.50 or more and 0.55 or more, respectively.
On the other hand, the Si / Al atomic ratio of the entire 8-membered SAPO measured by ICP analysis is generally in the range of 0.05 to 0.30, although it varies depending on the synthesis conditions.
[0033]
As described above, the 8-membered ring SAPO of the present invention has an ICP atomic ratio of Si / Al on the crystal particle surface measured by X-ray photoelectron spectroscopy using Al—Kα ray (1486.7 eV) as the X-ray source. 0.50 or more, which is larger than the Si / Al atomic ratio of the entire crystal grain measured by analysis, is preferable, and a range of 0.50 to 2.20 is more preferable. On the other hand, the atomic ratio of Si / P on the crystal particle surface measured by X-ray photoelectron spectroscopy is preferably 0.55 or more, and more preferably in the range of 0.55 to 3.10. On the other hand, in the 8-membered ring SAPO of the present invention, the Si / Al atomic ratio of the entire crystal particles is preferably in the range of 0.05 to 0.30.
[0034]
The amorphous oxide layer of the present invention is mainly composed of oxides containing silicon, aluminum, and phosphorus, but may contain elements other than silicon, aluminum, and phosphorus.
[0035]
The amorphous oxide layer is formed after the crystallization of the SAPO crystal grain body is mostly completed. That is, SAPO having an amorphous oxide layer on the surface of the present invention is obtained by hydrothermally treating a raw material mixture containing an organic amine and / or an organic ammonium salt, an aluminum compound, a phosphorus compound, a silicon compound, and water, and at least a crystal thereof. It is synthesized through two steps: a first step for generating a mass portion and a second step for forming an amorphous oxide layer on the surface of the crystal grains by further hydrothermal treatment.
[0036]
Specifically, the first step is a process in which most of the raw material mixture is crystallized in the generally known method for producing 8-membered ring SAPO, and the second step is a crystallization in the first step. This refers to a step of hydrothermally treating the converted 8-membered ring SAPO in a solution containing a silicon component.
In the production method of 8-membered SAPO in the present invention to be described later, the first step is a hydrothermal treatment at 80 to 130 ° C. for 1 hour or more where crystallization does not substantially proceed, and then the crystallization proceeds remarkably 150 to This corresponds to the process of hydrothermal treatment within a temperature range of 200 ° C. for 1 to 10 hours. On the other hand, after the 8-membered ring SAPO crystallizes by hydrothermal treatment for 1 to 10 hours in the temperature range of 150 to 200 ° C., the second step continues to hydrothermal treatment in the temperature range of 150 to 200 ° C. Correspond.
[0037]
The thickness and surface composition of the amorphous oxide layer can be controlled by the hydrothermal treatment conditions in the second step.
The thickness of the amorphous oxide layer increases as the hydrothermal treatment time is increased. For example, in the case of SAPO-34, the hydrothermal treatment at a temperature of 170 ° C. is 2.5 nanometers for 5 hours and 7 nanometers for 50 hours. The meter is 13 nanometers for 100 hours and 25 nanometers for 175 hours. The formation rate of the amorphous oxide layer varies depending on the temperature. By utilizing such properties and changing the temperature and time of hydrothermal treatment, the thickness and surface composition of the amorphous oxide layer can be controlled. In addition, while analyzing the thickness and surface composition of the amorphous oxide layer over time, the thickness and surface composition can be controlled to be suitable for reactions such as the production of methylamines by the reaction of methanol and ammonia.
[0038]
The hydrothermal treatment temperature and time of the second step are such that once the 8-membered SAPO crystal particles are formed by the hydrothermal treatment of the first step, the crystal particles are retained in the synthetic mother liquor even after cooling to room temperature. The formation of the amorphous oxide layer proceeds slowly even at room temperature, but is not particularly limited. However, from a practical viewpoint, the hydrothermal treatment in the second step is preferably performed for 10 hours or more within a temperature range of 150 to 200 ° C.
[0039]
The formation rate of the amorphous oxide layer can be controlled by the concentration of the silicon compound in the synthetic mother liquor in addition to the above temperature and time. Therefore, in the present invention, a silicon compound may be further added before or during the second step, which is particularly preferable when the formation rate of the amorphous oxide layer is slow. Examples of the silicon compound that can be used include powdered silica, silica sol, and orthosilicic acid. Particularly preferred is silica sol. Further, in addition to the silicon compound, a compound containing an element such as yttrium, titanium, zirconium, iron, or tin may be added as appropriate.
[0040]
As described in the prior art, crystalline molecular sieves in which a pure silica layer is formed around the SAPO main body are well known, for example, as disclosed in JP-T-11-508901. In addition, as disclosed in Japanese Patent Application Laid-Open No. 7-2740 and Japanese Patent Application Laid-Open No. 11-35527, ammonium-type mordenite is treated with tetrachlorosilane in the gas phase, and organosilicon compound in liquid phase. And silylation-treated.
However, the structure of the surface silica layer in these SAPOs has not been investigated. According to the literature, Miki Niwa, Yuichi Murakami, Journal of the Chemical Society of Japan, p.410-p.419 (1989), the regular structure of SAPO is exposed. It has been shown that the tetrahedral structures of silica are regularly arranged on the surface, which is considered to form a structure similar to the crystalline molecular sieve body (silica epitaxy growth). In addition, recent literatures, Dairyo Tsuji, Atsuko Nomura, Kazunari Domen, HA Begum, Naobu Katada, Miki Niwa, Catalysis Magazine, Vol.44, p.483-p.485 (2002) are vapor deposition methods. According to the transmission electron microscope observation of the silica layer, it is described that the silica layer has an ordered structure which is not an amorphous structure but grown by being controlled by the structure of the outer surface of the zeolite. Thus, the silica layer produced | generated by the modification method by a conventionally well-known silicon compound is thought to be crystalline, and differs from the amorphous oxide layer of this invention.
[0041]
Further, in these conventionally known methods, in the case of the gas phase method, the silica layer is formed by drying the crystalline molecular sieve under limited conditions, treatment with tetrachlorosilane under specific conditions, and the treatment. It is made with many detailed processes and precise control, such as cleaning and removing chlorine components. On the other hand, the silylation treatment in the liquid phase also involves many subtle control techniques and many processes, such as the control of the water content of the crystalline molecular sieve and the treatment of the surface of the crystalline molecular sieve using hydrolysis of the organosilicon compound. Made. On the other hand, since the amorphous oxide layer in the present invention is formed in the process of synthesizing the 8-membered ring SAPO, the number of steps is much smaller than that of a conventionally known method, and the control of the catalyst performance is very simple. It is economical.
[0042]
That is, the presence of an amorphous oxide layer on the surface of the synthesized 8-membered ring SAPO, the presence and thickness of the amorphous oxide layer greatly affect the catalyst performance, the thickness of the amorphous oxide layer It has never been known that the amorphous oxide layer of the present invention can be precisely controlled by hydrothermal treatment conditions during the formation of the amorphous oxide layer during the synthesis of the 8-membered ring SAPO. The 8-membered ring SAPO having a concept and essence is completely different from a crystalline molecular sieve modified with silica such as silica-modified SAPO silylated in the liquid phase.
[0043]
In the present invention, as the hydrothermal treatment conditions, the raw material mixture is hydrothermally treated for 1 hour or more at 80 to 130 ° C. in which the crystallization of the 8-membered ring SAPO does not substantially proceed in the hydrothermal treatment of the first step, Hydrothermal treatment is performed within a temperature range of 150 to 200 ° C. in which crystallization is remarkably advanced, and then, as a second step, treatment including a step of hydrothermal treatment within a temperature range of 150 to 200 ° C. is performed. This makes Al₂O_ThreeAmorphous oxide with high purity and crystallinity and controlled Si / Al molar ratio and thickness even when the amount of templating agent used is less than 1.0 times the number of moles It became possible to stably produce an 8-membered ring SAPO having a layer and excellent catalytic activity and dimethylamine selectivity. That is, in the first step, a process of hydrothermal treatment for 1 hour or more under a relatively mild temperature condition of 80 to 130 ° C. is provided so that the template agent can be effectively used. It has become possible to reduce the amount to the original required amount present in the crystal.
[0044]
Another feature of the present production method is that the catalyst yield improves as the amount of the templating agent used decreases. This is because the yield of the catalyst is greatly increased compared to the conventionally known methods due to the two effects that the amount of the templating agent used is small and the catalyst yield is improved, so that the catalyst manufacturing cost can be greatly reduced. It is very convenient for industrial production. Thus, compared with the conventionally known methods that require an excess of the templating agent, the production method of the present application is not limited to merely reducing the cost of using the templating agent and the disposal processing cost, and the catalyst production cost due to the high catalyst yield. Therefore, it is greatly improved in terms of economy.
[0045]
The reason why the catalyst yield is improved is that the conventionally known method requiring a large amount of alkali templating agent inevitably increases the pH of the raw material mixture, and the solubility of silicon, aluminum, and phosphorus compounds that are constituents of SAPO Can be explained by assuming that the yield of the catalyst is reduced. The pH after hydrothermal treatment in a conventionally known method is in the range of 8 or more, but is generally in the range of 5.5 to 7.5 in the present production method.
[0046]
Normally, 8-membered ring SAPO uses compounds such as tetraethylammonium hydroxide, morpholine, cyclohexylamine, and diethylethanolamine as a template agent, and uniformly mixes the template agent, silicon compound, aluminum compound, phosphorus compound, and water. Then, it is synthesized by hydrothermal treatment in an autoclave at a temperature of 150 to 200 ° C. for several hours to 200 hours.
aR, bSiO₂, CAl₂O_Three, DP₂O_Five, EH₂O ··· Formula (1)
The templating agent is Al when the mixture to be hydrothermally treated is represented by the composition formula shown in the above formula (1).₂O_ThreeIn general, the amount is 1 to 3 times the number of moles.
As mentioned in the prior art, the amount of templating agent used is Al.₂O_ThreeIf the amount is less than 1 times the number of moles, it seems difficult to synthesize a pure 8-membered ring SAPO, and no examples of successful synthesis are known. In addition to the documents listed above, for example, US Pat. No. 5,126,308 describes a method for synthesizing SAPO for producing olefins from methanol. Tetraethylammonium hydroxide as a templating agent and di-n -The total amount of propylamine used is Al₂O_ThreeIt is 1.0 times or more of the number of moles. In addition, US Pat.No. 5,663,471 describes a production method of SAPO, but the amount of tetraethylammonium hydroxide used as a templating agent is Al.₂O_Three2.0 times the number of moles.
[0047]
The 8-membered ring SAPO before firing includes templating agent molecules in the pores. The amount of the templating agent present in such pores can be determined by performing composition analysis such as ICP, weight analysis such as TG, and loss on firing measurement (LOI) on the sample before firing. . L Marchese, A. Frache, E. Gianotti, G. Marta, M. Causa, S. Coluccia, Microporous, and Mesoporous Materials30 (1999) p.145-153 relates to the synthesis of SAPO-34 using morpholine as a templating agent, but 1.5 templating agent molecules are encapsulated in the cage of SAPO-34 before firing. State things. This amount is Al₂O_ThreeWhen converted to a ratio to the number of moles, the amount is 0.49 times. Although it is desirable to be able to synthesize pure 8-membered ring SAPO with the amount of templating agent used 0.49 times this amount, no such example has been known so far.
[0048]
As shown in Comparative Examples 1 to 3 in the Examples section in the subsequent stage, the amount of the templating agent used under the conventional hydrothermal treatment conditions without performing the hydrothermal treatment for 1 hour or more in the temperature range between 80 to 130 ° C. Al₂O_ThreeIn addition to the 8-membered ring SAPO, the AFI-type structure that is not an 8-membered ring SAPO, such as SAPO-5, or the JCPDS card as defined by the International Center for Diffraction Data. Since the structure attributed to aluminum phosphate described in No. 20-0045 is produced, the purity and crystallinity of the resulting 8-membered ring SAPO are low.
[0049]
Of the hydrothermal treatment in the first step, when the hydrothermal treatment is performed at 80-130 ° C for 1 hour or longer, the amount of the mold agent used is Al.₂O_ThreeThe reason why a pure and highly crystalline 8-membered ring SAPO can be produced stably even if the amount is less than 1.0 times the number of moles is not well understood. For example, in the case of a shabasite-type 8-membered ring SAPO, It can be explained by thinking like this.
When hydrothermal treatment is performed for 1 hour or more at 80 to 130 ° C in the hydrothermal treatment of the first step, a double 6-membered ring structure (Double-six-ring) constituting the skeleton of the shabasite type 8-membered ring SAPO -structure) and shabasite-type 8-membered ring SAPO nuclei are formed in the synthetic mother liquor, so when hydrothermally treated at a temperature of 150 to 200 ° C, the shabasite-type 8-membered ring SAPO rapidly crystallizes. It is thought to go forward.
On the other hand, if hydrothermal treatment is not performed for 1 hour or more at 80 to 130 ° C., the formation amount of double 6-membered ring structure and shabasite type 8-membered SAPO nucleus in the synthetic mother liquor becomes insufficient, and 150 Even if hydrothermal treatment is performed at a temperature of ˜200 ° C., it is considered that SAPO having an AFI type structure which is not an 8-membered ring SAPO is generated or crystallization is not completely promoted. Such a phenomenon is unlikely to occur when the amount of the templating agent used is large, but is considered to become more prominent as the amount of the templating agent decreases.
[0050]
The purity of the 8-membered ring SAPO can be determined by X-ray diffraction. For example, the purity of the shabasite-type 8-membered ring SAPO is determined by the ratio of the peak intensity of the (100) plane of the AFI structure to the peak intensity of the (100) plane of the shabasite structure measured by X-ray diffraction. be able to. The peaks of the (100) plane of the shabasite structure and the (100) plane of the AFI structure are 2θ / θ methods using CuKα rays and 2θ is at the position of about 9.5 degrees and about 7.4 degrees, respectively. appear.
[0051]
Since the effective pore diameter of 8-membered SAPO is about 4 angstroms, trimethylamine with a molecular size of 6.3 x 5.8 x 4.1 angstroms is found out of the pores when producing methylamines by the reaction of methanol and ammonia. It has a feature that dimethylamine which cannot be used as a raw material for solvents, pharmaceuticals, surfactants and the like can be selectively produced. In contrast, the effective pore diameter of SAPO-5 having an AFI structure that is not an 8-membered SAPO is about 7 angstroms, so that trimethylamine molecules can pass through. Therefore, for example, in the case of a shabasite-type 8-membered ring SAPO, SAPO with a ratio of the peak intensity of the (100) plane of the AFI structure to the peak intensity of the (100) plane of the shabasite structure exceeds 0.02. When it is used for dimethylamine, since more trimethylamine is produced, dimethylamine selectivity is lowered. For this reason, the ratio of the peak intensity of the (100) plane of the AFI structure to the peak intensity of the (100) plane of the preferred chabasite structure of the shabasite type 8-membered SAPO in the present invention is 0.02. It is as follows.
[0052]
The 8-membered ring SAPO obtained by the method of the present invention has a high purity and high crystallinity, and an amorphous oxide layer having a thickness or surface composition ratio in the preferred range described above. It exhibits excellent activity and dimethylamine selectivity in the production of methylamines by the above reaction, the reaction between methanol and monomethylamine, or the disproportionation reaction of monomethylamine.
[0053]
The temperature control method in the hydrothermal treatment of the present invention is the hydrothermal treatment in the first step in the temperature range of 80 to 130 ° C. over 1 hour and then in the temperature range of 150 to 200 ° C. for 1 to 10 hours. The hydrothermal treatment in the second step includes a hydrothermal treatment for 10 hours or more within a temperature range of 150 to 200 ° C.
Among them, as the hydrothermal treatment in the first step, hydrothermal treatment is performed at a constant temperature of 95 to 125 ° C. for 3 to 24 hours, and as part of the crystallization step in the first step and the hydrothermal treatment in the second step, 150 The condition of hydrothermal treatment for 10 to 150 hours in a temperature range of ~ 200 ° C is that a stable and stable crystalline silicoaluminophosphate molecular sieve with a highly crystalline shabasite-type 8-oxygen ring pore is obtained. Therefore, it is particularly preferable as a temperature control method in hydrothermal treatment.
[0054]
In the first step, after hydrothermal treatment in the temperature range of 80 to 130 ° C for 1 hour or more, hydrothermal treatment in the temperature range of 150 to 200 ° C has excellent catalytic activity and dimethylamine selectivity. Although the catalyst can be produced stably, for example, if the previous hydrothermal treatment is carried out at a temperature exceeding 130 ° C. for 1 hour or more, the formation of an AFI-type structure that is not an 8-membered SAPO becomes prominent, and dimethylamine selectivity Decreases. On the other hand, when it is carried out at a temperature of less than 80 ° C. for 1 hour or longer, the silicon content of the entire crystalline silicoaluminophosphate molecular sieve having 8-oxygen ring pores is reduced and the catalytic activity is lowered.
[0055]
In the hydrothermal treatment performed in the temperature range of 80 to 130 ° C. in the first step, when a preferable temperature rising pattern is given in the case of performing the temperature rising operation, a pattern in which the temperature is raised from room temperature to 170 ° C. at a constant rate in 6 hours, A pattern in which the temperature is raised from room temperature to 80 ° C in 1 hour and the temperature is raised from 80 ° C to 170 ° C in 3 hours at a constant rate. The temperature is raised from room temperature to 110 ° C in 2 hours and held at 110 ° C for 5 hours, then 170 Examples include a pattern in which the temperature is raised to ° C.
On the other hand, it is not preferable to raise the temperature between 80 and 130 ° C. at a rate of 70 ° C./hour or more because the formation of the AFI structure becomes remarkable. Further, when the temperature is raised to 80 ° C. at a rate of 100 ° C./h or more, the raw material mixture may be solidified, which is also not preferable. In the first step, there is no particular limitation on the temperature raising condition between the hydrothermal treatment performed within the temperature range of 80 to 130 ° C and the hydrothermal treatment performed within the temperature range of 150 to 200 ° C.
[0056]
The preferred treatment time of the hydrothermal treatment performed in the temperature range of 150 to 200 ° C. in the second step varies depending on the hydrothermal treatment temperature and the amount of silicon used in the raw material mixture, but it takes 10 hours to sufficiently form the amorphous oxide layer. That is all you need. More preferably, it is in the range of 10 to 150 hours, more preferably in the range of 20 to 120 hours, in which an amorphous oxide layer having an appropriate thickness and surface composition ratio can be stably formed on the crystal particle surface. The reason is that an 8-membered ring SAPO having an amorphous oxide layer having a thickness and surface composition exhibiting excellent catalytic activity and dimethylamine selectivity can be stably produced.
[0057]
The agitation during the hydrothermal treatment is preferably agitation rather than standing, and more preferably, the hydrothermal treatment mixture is sufficiently uniformly mixed.
[0058]
In the production of the 8-membered ring SAPO of the present invention, examples of the silicon compound used as a raw material include powdered silica, silica sol, orthosilicic acid, and tetraethoxysilane. Particularly preferred is silica sol. The amount of silicon compound used is not particularly limited, but when the raw material mixture to be hydrothermally treated is expressed as an oxide ratio, Al₂O_ThreeAgainst SiO₂A molar ratio of 0.1 to 0.6 is preferable. Examples of the aluminum compound include pseudoboehmite, boehmite, dibsite, bayerite, and aluminum oxide such as γ-alumina, aluminum hydroxide, hydrated aluminum oxide, and aluminum alkoxide such as aluminum triisopropoxide. . In view of the raw material price, availability, and reactivity, pseudoboehmite is particularly preferable among them. On the contrary, the use of an aluminate such as sodium aluminate is not preferable because it requires an ion exchange of a cation such as sodium ion in addition to the usually required baking, and the post-treatment is troublesome.
[0059]
Orthophosphoric acid is particularly preferable as the phosphorus compound used as a raw material, but is not limited thereto. The amount of phosphoric acid used is not particularly limited, but when the raw material mixture used for hydrothermal treatment is expressed in terms of oxide ratio, Al₂O_ThreeP against₂O_FiveThe molar ratio is preferably 0.7 to 1.1. Moreover, you may use aluminum phosphate instead of the said aluminum compound and a phosphorus compound or with the said aluminum compound and a phosphorus compound. The amount of water used is not particularly limited as long as it is a slurry concentration that can be uniformly stirred, but considering industrial production efficiency, Al₂O_ThreeThe molar ratio of water to water is preferably 100 or less.
[0060]
As the organic amine and organic ammonium salt used as the templating agent, primary amine, secondary amine, tertiary amine, quaternary ammonium salt, amino alcohol, and diamine can be used. Organic amines and organic ammonium salts that are easy to synthesize 8-membered ring SAPO include tetraethylammonium hydroxide, triethylmethylammonium hydroxide, diethanolamine, diethylethanolamine, morpholine, methylbutylamine, diisopropylamine, di-n-propylamine, quinuclidine. , Cyclohexylamine, and N, N, N ′, N′-tetramethyl-1,6-hexanediamine. These organic amines and organic ammonium salts may be used alone or in combination of two or more organic amines and organic ammonium salts. Alkyl ammonium hydroxide may contain chloride or bromide as its raw material, but there is no particular problem. When producing a shabasite-type 8-membered ring SAPO, tetraethylammonium hydroxide is preferred among the templating agents in terms of average particle size and particle shape.
[0061]
The amount of organic amine and organic ammonium salt used to synthesize 8-membered SAPO is not particularly limited.₂O_ThreeEven if the ratio of the total number of moles of the organic amine and the organic ammonium salt to the number of moles of the aluminum compound converted into the above is in the range of 0.4 to 0.98, the above range is preferable because 8-membered ring SAPO having high purity and crystallinity can be synthesized. . Especially when synthesizing shabasite type 8-membered ring SAPO₂O_ThreeSince the ratio of the total number of moles of the organic amine and the organic ammonium salt to the number of moles of the aluminum compound converted to 0.4 can be synthesized in the range of 0.4 to 0.98, a shabasite-type 8-membered ring SAPO with high purity and crystallinity can be synthesized. preferable. Al₂O_ThreeShabasite type 8-membered ring SAPO can be synthesized even if the ratio of the total number of moles of organic amine and organic ammonium salt to 0.98 exceeds 0.98. And ammonium salt increase raw material costs and decrease catalyst yield. Further, these extra amines and ammonium salts are discharged as waste liquid in the separation / washing step after hydrothermal treatment, but this is not preferable in view of the increase in the treatment cost and the burden on the environment. When the ratio of the total number of moles of organic amine and organic ammonium salt is less than 0.40, the structure attributed to aluminum phosphate described in JCPDS card number 20-0045 comes to be produced, and catalytic activity and dimethylamine selectivity Decreases.
[0062]
Typical forms of the 8-membered ring SAPO include a cubic shape, a rectangular parallelepiped shape, a plate shape, a rod shape, a needle shape, a spherical shape, and an aggregate of these shapes. Among these forms, the preferred form of the shabasite-type 8-membered ring SAPO in the present invention is a crystal having an average particle diameter of 5 μm or less, a cubic shape, and a rectangular parallelepiped shape. Particularly preferred are crystals having an average particle diameter of 1 to 4 μm and a cubic or rectangular parallelepiped shape. Conversely, a plate-like form having an average crystal particle size of 1 μm or less or a form in which plate-like particles are aggregated to form a lump is not preferable. The reason is that the shabasite-type 8-membered ring SAPO having an average crystal particle size of 5 μm or less and a cubic or cuboid shape is excellent in producing methylamines by the reaction of methanol and ammonia. This is because it shows activity, dimethylamine selectivity and life performance. The average particle size can be easily measured with a laser diffraction particle size distribution meter. The particle shape can be observed with a scanning electron microscope.
[0063]
The 8-membered ring SAPO synthesized under the hydrothermal treatment conditions is filtered, decanted or centrifuged and then washed. Thereafter, it is dried at a temperature of 80 to 150 ° C. and fired. Firing is usually performed in a temperature range of 400 to 1000 ° C. in air or a mixed air stream of air and nitrogen. Most preferably, it is the temperature range of 500-900 degreeC.
[0064]
The 8-membered ring SAPO of the present invention is directly used as a catalyst for the reaction between methanol and ammonia, the reaction between methanol and monomethylamine, or the disproportionation reaction of monomethylamine by compression molding, tableting or extrusion molding. The It can also be applied to other catalytic reactions such as the production of lower olefins from methanol (MTO reaction).
[0065]
In the case of producing methylamines by carrying out the reaction of methanol and ammonia, the reaction of methanol and monomethylamine, or the disproportionation of monomethylamine using the 8-membered ring SAPO of the present invention, the form of the reaction is fixed. Either the bed method or the fluidized bed method can be used. The reaction temperature is preferably in the range of 200 to 400 ° C, particularly preferably in the range of 250 to 350 ° C. The reaction pressure is not particularly limited, but it is preferably carried out usually in a pressure range of 0.1 to 10 MPa.
[0066]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated with an Example and a comparative example, this invention is not limited by these examples.
The physical and chemical property measuring methods and methylamine synthesis methods used in this example are as follows.
(1) The catalyst yield is obtained by calculating the weight of the obtained solid material after calcination using the silica compound, aluminum compound, phosphorus compound, titanium compound, and zirconium compound in the raw material mixture charged in the autoclave.₂, Al₂O_Three, P₂O_Five, TiO₂, ZrO₂In addition, the weight was divided by the sum of the weights and multiplied by 100 and expressed in weight%. In addition, the weight of the obtained solid was measured after drying at 110 ° C. for 8 hours and in a sufficiently dried state (baked powder).
(2) The purity of the resulting solid material shabasite-type 8-membered ring SAPO was determined by X-ray diffraction of the calcined powder and represented by the AFI-type structure abundance ratio. The AFI type structure abundance ratio was determined by X-ray diffraction, and the peak intensity of the (100) plane of the AFI type structure was divided by the peak intensity of the (100) plane of the shabasite type structure.
(3) The degree of crystallinity is determined by measuring the calcined powder by X-ray diffraction and synthesizing according to the method of Catalyst Preparation Example 1 described in JP-A-2000-117114. The ratio was determined by the ratio of the peak intensity of the (100) plane of the shabasite structure of each fired powder to the peak intensity.
(4) The particle properties were determined by observation with a scanning electron microscope (FE-SEM observation).
(5) The average particle size was determined with a laser diffraction particle size distribution meter.
(6) X-ray photoelectron spectroscopic analysis is measured using calcined powder, and the surface composition ratio is determined from the peak area of the narrow spectrum of Si (2p), Al (2p), P (2p) bands, and the Scofield correction factor. It was obtained by correcting.
(7) The reaction test was performed by compressing or compressing the calcined powder, and then using a catalyst sized to 1 to 2 mm, using a raw material tank, a raw material supply pump, an inert gas introduction device, a reaction tube (inner diameter) 13 mmφ, 300 mm in length, SUS316), a flow reactor equipped with a cooling device, a sampling tank, a back pressure valve, and the like.
(8) The composition of the reaction product was determined by collecting a sample over 30 minutes and analyzing it with a gas chromatograph.
[0067]
1.8 member ring SAPO (Relationship with the amount of templating agent used and hydrothermal treatment conditions)
Examples 1-9 and Comparative Examples 1-9 are synthesis examples of 8-membered ring SAPO in which the amount of tetraethylammonium hydroxide, which is a templating agent, and the temperature rise conditions of hydrothermal treatment were changed. Table 1 summarizes the catalyst yield, AFI-type structure abundance ratio, crystallinity, particle shape, and particle diameter of Examples and Comparative Examples. The results of the reaction test are summarized in Table 2. In the reaction test, 2.5 g (3.5 ml) of the sized catalyst was charged into a reaction tube, a 1: 1 weight mixture of methanol and ammonia was 8.62 g per hour, and the space velocity (GHSV) was 2500 h.^-1At a temperature of 305 ° C. and a pressure of 2 MPa.
Example 1
A uniform mixture of 85 wt% phosphoric acid (46.12 g) and pure water (191.16 g) is cooled to 30 ° C or lower, and pseudoboehmite (26.32 g: SASOL GERMANY GmbH, PURAL SB, Al₂O_Three77.5% content) was added with stirring. After stirring this mixture for 30 minutes, 35 wt% aqueous tetraethylammonium hydroxide (79.94 g) was added to 30 ° C. or lower while cooling and stirring. After stirring this mixture for 1 hour, silica sol (18.04 g: Nissan Chemical Industries, Snowtex N, SiO₂(Content 20 wt%) was added and the mixture was further stirred for 30 minutes. The composition of this mixture in molar oxide ratio was as follows: 0.95 TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.3SiO₂: 75H₂O (TEAOH represents tetraethylammonium hydroxide). The obtained mixture was hydrothermally treated with stirring at 400 rpm in a stainless steel autoclave having an internal volume of 0.6 L. In the hydrothermal treatment, as the first step, the temperature of the contents is increased from 25 ° C. to 170 ° C. at 25 ° C./h, and a part of the crystallization step of the first step and the second step of 35 ° C. at 170 ° C. Held for a while. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged three times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 600 ° C. for 4 hours under an air stream to obtain a white powder (40.35 g). The catalyst yield was 77%. As a result of X-ray diffraction, this powder was an 8-membered ring SAPO having a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was good and was 1.00. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 1.8 μm. As shown in Table 2, the reaction results 6 hours after starting the distribution of the raw materials were a methanol conversion rate of 92 wt%, a monomethylamine selectivity of 39 wt%, a dimethylamine selectivity of 54 wt%, and a trimethylamine selectivity of 7 wt%.
[0068]
Example 2
Hydrothermal treatment is performed at the temperature of the contents at the first step from 25 ° C to 115 ° C at 73 ° C / h, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 73 ° C / h. The white baked powder (40.50 g) was obtained in the same manner as in Example 1 except that the temperature was raised at 1 ° C. and that the second crystallization step was carried out at 170 ° C. for 35 hours. It was. Table 1 shows the catalyst yield, AFI type structure abundance ratio, crystallinity, particle shape, and average particle diameter. In addition, Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0069]
Example 3
A white calcined powder (46.15 g) was obtained in the same manner as in Example 2 except that the amount of 35 wt% tetraethylammonium hydroxide aqueous solution was 63.14 g and the amount of pure water was 202.07 g. The composition in the molar oxide ratio of the hydrothermally treated mixture was as follows: 0.75 TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.3SiO₂: 75H₂O. Table 1 shows the catalyst yield, AFI type structure abundance ratio, crystallinity, particle shape, and average particle diameter. In addition, Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0070]
Example 4
Hydrothermal treatment is performed at the temperature of the contents, and as a first step, the temperature is raised from 25 to 80 ° C. at 73 ° C./h, from 80 to 130 ° C. at 50 ° C./h, and from 130 to 170 ° C. at 70 ° C./h. A white calcined powder (46.05 g) was obtained in the same manner as in Example 3 except that a part of the crystallization step of the first step and the second step were held at 170 ° C. for 35 hours. Table 1 shows the catalyst yield, AFI type structure abundance ratio, crystallinity, particle shape, and average particle diameter. In addition, Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0071]
Example 5
A white calcined powder (45.94 g, catalyst yield 88%) was obtained in the same manner as in Example 2 except that the amount of 35 wt% tetraethylammonium hydroxide aqueous solution was 42.10 g and the amount of pure water was 215.74 g. It was. The composition in the molar oxide ratio of the hydrothermally treated mixture was as follows: 0.50TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.3SiO₂: 75H₂O. As a result of X-ray diffraction, a small amount of JCPDS No. 20-0045 compound peak was observed in the calcined powder obtained in addition to the peak of the shabasite structure, but the same TEAOH / Al₂O_ThreeThe peak of the AFI type structure observed in the catalyst of Comparative Example 3 synthesized at the molar ratio was not observed. The crystallinity was 0.65, which was higher than that of Comparative Example 3. The particle shape was cubic crystals, and the average particle size was 1.1 μm. From this example, when performing hydrothermal treatment in the first step, the same TEAOH / Al as in Comparative Example 3 is maintained by holding at 115 ° C. for 5 hours.₂O_ThreeIt was found that an 8-membered ring SAPO having a shabasite structure with better purity and crystallinity can be obtained even at a molar ratio of 0.50.
[0072]
Example 6
A uniform raw material mixture of 85wt% phosphoric acid (46.12g), pure water (108.99g), and 35wt% tetraethylammonium hydroxide aqueous solution (63.14g) is cooled to 30 ° C or less, and pseudo boehmite (26.32g: SASOL GERMANY GmbH, PURAL NF, Al₂O_Three77.5% content) was added with stirring. After stirring this mixture for 1 hour, silica sol (18.04 g: Nissan Chemical Industries, Snowtex N, SiO₂20wt%) and titania sol (4.04g, Ishihara Sangyo Co., Ltd., STS-01, TiO₂Content 29.5 wt%) was added and stirred for another 30 minutes. The composition of this mixture in molar oxide ratio was as follows: 0.75 TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.3SiO₂: 0.075TiO₂: 50H₂O. The obtained raw material mixture was hydrothermally treated with stirring at 500 rpm in an autoclave made of stainless steel having an internal volume of 0.6 L. In the hydrothermal treatment, the temperature of the contents is raised from 25 ° C to 110 ° C at 65 ° C / h as the first step, held at 110 ° C for 5 hours, and then from 110 ° C to 160 ° C at 65 ° C / h. The temperature was raised at 150 ° C. for 35 hours at 160 ° C. as part of the crystallization step of the first step and the second step. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged three times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 800 ° C. for 4 hours under an air stream to obtain a white powder (48.30 g). The catalyst yield was 90%. As a result of X-ray diffraction, this powder was an 8-membered ring SAPO having a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was good and was 1.10. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 1.7 μm.
As shown in Table 2, the reaction results 6 hours after starting the distribution of the raw materials were a methanol conversion rate of 94 wt%, a monomethylamine selectivity of 37 wt%, a dimethylamine selectivity of 60 wt%, and a trimethylamine selectivity of 3 wt%.
[0073]
Example 7
Hydrothermal treatment is performed at 65 ° C / h from 25 ° C to 125 ° C at 65 ° C / h as the first step and held at 125 ° C for 24 hours, and then from 125 ° C to 170 ° C at 65 ° C / h. The white calcined powder (47.81 g) was obtained in the same manner as in Example 6 except that the temperature was raised at 145 ° C. and the second crystallization step was held at 170 ° C. for 35 hours as the second step. It was. Table 1 shows the catalyst yield, AFI type structure abundance ratio, crystallinity, particle shape, and average particle diameter. In addition, Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0074]
Example 8
Hydrothermal treatment is performed at 65 ° C / h from 25 ° C to 90 ° C at 65 ° C / h for the first step and held at 90 ° C for 5 hours, and then from 90 ° C to 165 ° C at 65 ° C / h. The white calcined powder (47.09 g) was obtained in the same manner as in Example 6, except that the temperature was raised at 165 ° C. and the second crystallization step was held for 12 hours at 165 ° C. It was. Table 1 shows the catalyst yield, AFI type structure abundance ratio, crystallinity, particle shape, and average particle diameter. In addition, Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0075]
Example 9
The 35 wt% tetraethylammonium hydroxide aqueous solution charge amount is 42.09 g, the pure water charge amount is 118.00 g, the silica sol charge amount is 24.05 g, and hydrothermal treatment is performed at a temperature of the contents from 25 ° C. to 115 ° C. as the first step. The temperature was raised to 20 ° C./h at 20 ° C./h, held at 115 ° C. for 5 hours, and then raised from 115 ° C. to 170 ° C. at 20 ° C./h. A white calcined powder (50.43 g, catalyst yield 92%) was obtained in the same manner as in Example 6 except that the process was carried out at 170 ° C. for 50 hours. The composition in the molar oxide ratio of the hydrothermally treated mixture was as follows: 0.50TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.4SiO₂: 0.075TiO₂: 50H₂O. Table 1 shows the catalyst yield, AFI type structure abundance ratio, crystallinity, particle shape, and average particle diameter. In addition, Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0076]
Comparative Example 1
Hydrothermal treatment is performed at 79 ° C / h from 25 ° C to 170 ° C as the first step at the temperature of the contents. Part of the crystallization step of the first step and 170 ° C as the second step for 42 hours A white fired powder (40.32 g) was obtained in the same manner as in Example 1 except that the holding was performed. As a result of X-ray diffraction of this powder, in addition to the peak of the shabasite type structure which is an 8-membered ring SAPO, the peak of an AFI type structure which is not an 8-membered ring SAPO was observed. The abundance ratio of AFI structure was 0.03. The peak of the compound JCPDS No. 20-0045 was not seen, but the crystallinity was poor, 0.89. The particle property was a cubic crystal, but a hexagonal columnar crystal that was considered to be an AFI type structure was observed. The average particle size was 1.8 μm. Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0077]
Comparative Example 2
Hydrothermal treatment was performed at 78 ° C / h from 25 ° C to 170 ° C as the first step at the temperature of the contents, and part of the crystallization step of the first step and 170 ° C as the second step for 35 hours. A white fired powder (43.30 g) was obtained in the same manner as in Example 3 except that the holding was performed. As a result of X-ray diffraction of this powder, in addition to the peak of the shabasite structure that is 8-membered ring SAPO, the peak of the AFI structure that is not 8-membered ring SAPO and the peak of the JCPDS number 20-0045 compound are seen. It was. The abundance ratio of AFI structure was 0.03. The crystallinity was poorly 0.79. Although the particle property was a rectangular parallelepiped crystal, hexagonal columnar crystals that were considered to be AFI type structures and amorphous materials that were considered to be amorphous compounds were observed. The average particle size was 1.5 μm. Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0078]
Comparative Example 3
Hydrothermal treatment was performed at 78 ° C / h from 25 ° C to 170 ° C as the first step at the temperature of the contents, and part of the crystallization step of the first step and 170 ° C as the second step for 35 hours. A white fired powder (43.40 g) was obtained in the same manner as in Example 5 except that the holding was performed. As a result of X-ray diffraction of this powder, in addition to the peak of the shabasite structure that is 8-membered ring SAPO, the peak of the AFI structure that is not 8-membered ring SAPO and the peak of the JCPDS number 20-0045 compound are seen. It was. The abundance ratio of AFI structure was 0.10. The crystallinity was poor and was 0.32.
[0079]
Comparative Example 4
A white calcined powder (45.51 g) was obtained in the same manner as in Example 2 except that the amount of 35 wt% tetraethylammonium hydroxide aqueous solution was 21.05 g and the amount of pure water was 229.43 g. The composition of the hydrothermally treated mixture in molar oxide ratio was as follows: 0.25TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.3SiO₂: 75H₂O. As a result of X-ray diffraction, the obtained fired powder was a structure of the JCPDS No. 20-0045 compound, and no peaks of the shabasite structure and the AFI structure were observed.
[0080]
Comparative Example 5
Hydrothermal treatment is performed at 65 ° C / h from 25 ° C to 135 ° C at 65 ° C / h as the first step and held at 135 ° C for 5 hours, and then from 135 ° C to 170 ° C at 65 ° C / h. The white calcined powder (47.65 g) was obtained in the same manner as in Example 6 except that the temperature was raised at 1 ° C. and the second crystallization step was held at 170 ° C. for 35 hours as the second step. It was. As a result of X-ray diffraction of this powder, in addition to the peak of the shabasite structure, the peak of the AFI structure was observed. The peak of the JCPDS No. 20-0045 compound was not observed. The AFI type structure abundance ratio was 0.04, and the crystallinity was 0.98. In addition to cubic crystals, acicular crystals that appear to be AFI type structures were observed. The average particle size was 1.9 μm. Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0081]
Comparative Example 6
Hydrothermal treatment is performed at 65 ° C / h from 25 ° C to 70 ° C at 65 ° C / h for the first step and held at 70 ° C for 5 hours, and then from 70 ° C to 170 ° C at 65 ° C / h. The white baked powder (45.65 g) was obtained in the same manner as in Example 6 except that the temperature was raised at 1 ° C. and the second crystallization step was held at 170 ° C. for 35 hours as the second step. It was. As a result of X-ray diffraction of this powder, in addition to the peak of the shabasite structure that is an 8-membered ring SAPO, the peak of the AFI structure was observed. The peak of the JCPDS No. 20-0045 compound was not observed. The AFI type structure abundance ratio was 0.03, and the crystallinity was 0.90. The particle properties were thick plate-like crystals. The average particle size was 1.5 μm. Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0082]
Comparative Example 7
A white calcined powder (36.40 g) was prepared in the same manner as in Example 9 except that the amount of 35 wt% tetraethylammonium hydroxide aqueous solution was 105.23 g, the amount of pure water was 76.93 g, and the stirring speed during hydrothermal treatment was 200 rpm. The catalyst yield was 66%). The composition of the hydrothermally treated mixture in molar oxide ratio was as follows: 1.25 TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.4SiO₂: 0.075TiO₂: 50H₂O. As a result of X-ray diffraction, the obtained fired powder was a pure shabasite-type structure, and no peaks of the AFI-type structure and JCPDS No. 20-0045 compound were observed. The degree of crystallinity was as bad as 0.65. The particle properties were thin plate crystals, and the average particle size was 0.6 μm. Table 2 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0083]
Comparative Example 8
Zirconia-modified SAPO-34 was synthesized in the same manner as Catalyst Preparation Example 1 described in JP-A-2000-117114. Cool a uniform mixture of 35 wt% tetraethylammonium hydroxide aqueous solution (151.41 g) and pure water (84.60 g) to 5 ° C, add aluminum isopropoxide (81.80 g: Nacalai Tesque, Inc.), and stir at high speed for 15 minutes did. Next, silica sol (18.04 g) and zirconium oxide powder (2.40 g, Daiichi Rare Element Chemical Co., Ltd., RC-100) were added and stirred at high speed until uniform for 5 minutes. Furthermore, 85 wt% phosphoric acid (46.20 g) was added, and the mixture was similarly stirred for 5 minutes, and then the lye treatment was performed for 1 hour. The composition of this mixture in molar oxide ratio was: 1.80 TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.3SiO₂: 0.097ZrO₂: 57H₂O. The obtained mixture was hydrothermally treated with stirring at 200 rpm in a stainless autoclave having an internal volume of 0.6 L. The hydrothermal treatment was performed by increasing the temperature of the contents from 25 ° C. to 200 ° C. at 75 ° C./h and holding at 200 ° C. for 4 hours. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged four times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 600 ° C. for 4 hours under an air stream to obtain a white powder (34.21 g). The catalyst yield was 62%. As a result of X-ray diffraction, this powder was a pure shabasite type structure, and no peak of AFI type structure or JCPDS No. 20-0045 compound was observed. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 1.4 μm. As shown in Table 2, the reaction results 6 hours after starting the distribution of the raw materials were a methanol conversion rate of 90 wt%, a monomethylamine selectivity of 41 wt%, a dimethylamine selectivity of 54 wt%, and a trimethylamine selectivity of 5 wt%.
[0084]
Comparative Example 9
In the same manner as in Comparative Example 8, zirconia-modified SAPO-34 was synthesized to obtain a white calcined powder (32.55 g, catalyst yield 59%). As a result of X-ray diffraction, this powder was a pure shabasite type structure, and no peak of AFI type structure or JCPDS No. 20-0045 compound was observed. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 1.6 μm. The reaction results 6 hours after starting the distribution of the raw materials are shown in Table 2.
[0085]
[Table 1]

[0086]
[Table 2]

[0087]
Use tetraethylammonium hydroxide in Al₂O_ThreeComparative Examples 1 to 3 and 5 in which the amount was 1.0 times or less the number of moles of the aluminum compound converted into 1 and hydrothermal treatment in the first step was performed at a temperature between 80 ° C. and 130 ° C. for less than 1 hour. The catalyst of No. 6 showed an AFI type structure that was not an 8-membered SAPO, and the crystallinity was low. Moreover, the methanol conversion rate and dimethylamine selectivity of the reaction using these catalysts were low. On the other hand, in the catalysts of Examples 1 to 9 in which the hydrothermal treatment in the first step was performed at a temperature between 80 ° C. and 130 ° C. for 1 hour or more, the AFI type structure, the JCPDS No. 20-0045 compound was It was not seen and the crystallinity was good. Moreover, the methanol conversion rate and dimethylamine selectivity of the reaction using these catalysts were better than those of Comparative Examples 1, 2, 5, and 6. In particular, the template agent tetraethylammonium hydroxide is₂O_ThreeThe methanol conversion of the catalysts of Examples 3 and 6, which were maintained at 115 ° C. and 125 ° C. in the first step and hydrothermally treated for 1 hour or more using 0.75 times the number of moles of pseudoboehmite converted to Dimethylamine selectivity was excellent. In Comparative Examples 7 to 9, tetraethylammonium hydroxide was changed to Al₂O_ThreeIn this example, the amount is 1.0 times or more the number of moles of the aluminum compound converted to. From these examples, TEAOH / Al₂O_ThreeEven when the molar ratio of the catalyst exceeds 0.98, a pure shabasite-type 8-membered ring SAPO can be synthesized, but the catalyst yield is as low as 59 to 66%, indicating that the catalyst productivity is low. Moreover, the methanol conversion rate and the dimethylamine selectivity were also low compared with the catalyst of Examples 1-9, and especially the catalyst performance of the comparative example 7 which is a plate-shaped crystal was low. As is clear from these examples, even with a small amount of templating agent that has been considered difficult in the past, by controlling the temperature during the hydrothermal treatment, a shabasite type 8 having good purity, crystallinity, and catalytic performance is good. Member ring SAPO is obtained, rather TEAOH / Al₂O_ThreeIt can be seen that the smaller the molar ratio of 0.75, the better the crystallinity and catalyst performance. In particular, Comparative Examples 8 and 9 are examples in which the synthesis reproducibility of the catalyst preparation example described in JP-A-2000-117114 was examined, but the methanol conversion rate may not be reproduced as in Comparative Example 9. I understood. In Comparative Example 4, tetraethylammonium hydroxide was changed to Al₂O_ThreeIn this example, 0.25 times the amount of pseudoboehmite converted to ## STR3 ## was used, and the obtained solid product was a structure of the compound JCPDS No. 20-0045, which is a shabasite type 8-membered ring. SAPO was not obtained. On the other hand, in Example 9 in which 0.50 times the amount of tetraethylammonium hydroxide was used, a pure shabasite-type 8-membered ring SAPO could be synthesized and the catalytic performance was also good.
[0088]
2. Example using tetraethylammonium hydroxide, diethanolamine, and cyclohexylamine as templating agents
Example 10 is a synthesis example of a shabasite type 8-membered ring SAPO using a mixture of tetraethylammonium hydroxide and diethanolamine as a templating agent, and Example 11 using cyclohexylamine as a templating agent. The reaction test results of the obtained catalyst are shown in Table 3. The reaction test was conducted in the same manner as in Examples 1-9.
[0089]
Example 10
A homogeneous mixture of 85wt% phosphoric acid (41.51g), pure water (98.70g), 35wt% tetraethylammonium hydroxide aqueous solution (42.10g), and diethanolamine (6.30g) is cooled to 30 ° C or less, and pseudoboehmite is added thereto. (26.32g: SASOL GERMANY GmbH, PURAL NF, Al₂O_Three77.5% content) was added with stirring. After stirring this mixture for 1 hour, silica sol (30.06 g: Nissan Chemical Industries, Snowtex N, SiO₂Content 20 wt%) and zirconium oxide powder (1.25 g, Daiichi Rare Element Chemical Co., Ltd., RC-100) were added and stirred for another 30 minutes. The composition of this mixture in molar oxide ratio was as follows: 0.50TEAOH: 0.30DEA: 1.0Al₂O_Three: 0.9P₂O_Five: 0.5SiO₂: 0.05ZrO₂: 45H₂O (DEA represents diethanolamine). The obtained mixture was hydrothermally treated with stirring in a stainless steel autoclave. In the hydrothermal treatment, the temperature of the contents is raised from 25 ° C to 115 ° C at 65 ° C / h as the first step, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 65 ° C / h. The temperature was raised at 170 ° C. for 35 hours at 170 ° C. as part of the crystallization step of the first step and the second step. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged three times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 600 ° C. for 4 hours under an air stream to obtain a white powder (44.17 g). The catalyst yield was 85%. As a result of X-ray diffraction, this powder was an 8-membered ring SAPO having a pure shabasite type structure, and no peak of AFI type structure or JCPDS No. 20-0045 compound was observed. The crystallinity was good and was 1.03. The particle properties were rectangular parallelepiped crystals, which were well aligned in size and shape. The average particle size was 2.5 μm. Table 3 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0090]
Example 11
A uniform mixture of 85 wt% phosphoric acid (43.82 g) and pure water (145.50 g) was cooled to 30 ° C. or lower, and aluminum triisopropoxide (81.70 g: Nacalai Tesque, Inc.) was added thereto with stirring. After the mixture was stirred for 30 minutes, cyclohexylamine (15.90 g) was added with stirring. After stirring this mixture for 1 hour, silica sol (24.05 g: Nissan Chemical Industries, Snowtex N, SiO₂(Content 20 wt%) was added and the mixture was further stirred for 30 minutes. The composition of this mixture in molar oxide ratio was as follows: 0.80 cyclohexylamine: 1.0Al₂O_Three: 0.95P₂O_Five: 0.40SiO₂: 47.5H₂O. The obtained mixture was hydrothermally treated with stirring in a stainless steel autoclave. In the hydrothermal treatment, the temperature of the contents is raised from 25 ° C to 115 ° C at 65 ° C / h as the first step, held at 115 ° C for 5 hours, and then from 115 ° C to 180 ° C at 65 ° C / h. The temperature was raised at 150 ° C. for 35 hours at 180 ° C. as part of the crystallization step of the first step and as the second step. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged three times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 600 ° C. for 4 hours under an air stream to obtain a white powder (43.90 g). The catalyst yield was 84%. As a result of X-ray diffraction, this powder was an 8-membered ring SAPO having a pure shabasite type structure, and no peak of an AFI type structure or a compound of JCPDS No. 20-0045 was observed. The crystallinity was good and was 1.00. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 3.5 μm. Table 3 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0091]
[Table 3]

[0092]
In both examples, Al₂O_ThreeIt can be seen that an 8-membered SAPO having a pure shabasite structure can be obtained with a template agent amount of less than 1.0 times the amount of the aluminum compound converted into 1 and the catalyst performance is also good.
[0093]
3. Relationship between surface composition and thickness of amorphous oxide layer and catalyst performance.
Examples 12 to 17 and Comparative Examples 10 and 11 are examples relating to the surface composition, thickness, and catalytic performance of an amorphous oxide layer of 8-membered ring SAPO having a shabasite type structure. Si / Al atomic ratio (bulk Si / Al atomic ratio), surface Si / Al atomic ratio, Si / P atomic ratio on the surface, amorphous Table 4 shows the thickness of the oxide layer, and Table 5 shows the results of the reaction test. The reaction test was conducted in the same manner as in Examples 1-9.
[0094]
Example 12
The calcined powder obtained in Example 2 was analyzed by ICP and XPS. As a result, the Si / Al atomic ratio of the entire crystal grain was 0.15, the Si / Al atomic ratio on the surface was 0.60, and the Si / P surface was on the surface. The atomic ratio of was 0.66.
[0095]
Example 13
The calcined powder obtained in Example 6 was analyzed by ICP and XPS. As a result, the Si / Al atomic ratio of the entire crystal particle was 0.14, the Si / Al atomic ratio on the surface was 1.07, and the Si / P surface was on the surface. The atomic ratio of was 1.24.
[0096]
Example 14
To a uniform mixture of 85% phosphoric acid (89.8g), pure water (183.9g) and 35wt% tetraethylammonium hydroxide aqueous solution (122.9g), pseudoboehmite (51.3g: SASOL GERMANY GmbH, PURAL NF, Al₂O_Three77.5% content) was added with stirring. After stirring this mixture for 1 hour, silica sol (46.8 g: Nissan Chemical Industries, Snowtex N, SiO₂20wt%) and titania sol (5.3g, Ishihara Sangyo Co., Ltd., STS-01, TiO₂Content 29.5 wt%) was added and stirred for another 30 minutes. The pH of this mixture was 2.95 and the composition in molar oxide ratio was as follows: 0.75 TEAOH: 1.0Al₂O_Three: 1.0P₂O_Five: 0.4SiO₂: 0.05TiO₂: 50H₂O. The obtained mixture was hydrothermally treated while stirring at 700 rpm in a stainless steel autoclave having an internal volume of 0.6 L. In the hydrothermal treatment, the temperature of the contents is raised from 20 ° C / h to 25 ° C to 115 ° C as the first step, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The temperature was raised at 150 ° C. for 50 hours at 170 ° C. as part of the crystallization step of the first step and the second step. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged three times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 600 ° C. for 4 hours under an air stream to obtain a white powder (88.2 g). The catalyst yield was 83%, which was good. As a result of X-ray diffraction, this powder was a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was good and was 1.05. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 2.2 μm. The Si / Al atomic ratio of the entire crystal particles of the fired powder was 0.16, the Si / Al atomic ratio on the surface was 1.61, and the atomic ratio of Si / P on the surface was 2.45. Also, from observation with a scanning transmission electron microscope, the crystal particles of the fired powder had an amorphous oxide layer having a thickness of 7 nanometers. Table 5 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0097]
Example 15
Hydrothermal treatment is performed at the temperature of the contents, as a first step from 25 ° C to 115 ° C at a rate of 20 ° C / h, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The white calcined powder (86.2 g, catalyst yield) was obtained in the same manner as in Example 14 except that a part of the first crystallization step and the second step were held at 170 ° C. for 100 hours. 81%). As a result of X-ray diffraction, this powder was an 8-membered ring SAPO having a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was good and was 1.03. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 2.4 μm. The obtained sintered powder had a Si / Al atomic ratio of 0.15 in the entire crystal particles, a surface Si / Al atomic ratio of 1.98, and a surface Si / P atomic ratio of 2.92. Further, from the observation with a scanning transmission electron microscope, the crystal particles of the fired powder had an amorphous oxide layer having a thickness of 13 nanometers. Table 5 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0098]
Example 16
Hydrothermal treatment is performed at the temperature of the contents, as a first step from 25 ° C to 115 ° C at a rate of 20 ° C / h, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The white calcined powder (45.70 g, catalyst yield) was obtained in the same manner as in Example 3 except that a part of the first crystallization step and the second step were held at 170 ° C. for 30 hours. 87%). As a result of X-ray diffraction, this powder was a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was 1.00. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 1.9 μm. The obtained sintered powder had a Si / Al atomic ratio of 0.14 for the entire crystal particles, a surface Si / Al atomic ratio of 0.65, and a surface Si / P atomic ratio of 0.75. Table 5 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0099]
Example 17
Hydrothermal treatment is performed at the temperature of the contents, as a first step from 25 ° C to 115 ° C at a rate of 20 ° C / h, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The temperature is raised at a temperature of 170 ° C. for 20 hours as part of the first crystallization step and the second step, and then silica sol (6.1 g: Nissan Chemical Industries, Snowtex N, SiO₂The white calcined powder (46.21 g, catalyst yield 88%) was added in the same manner as in Example 16 except that the content was added to the hydrothermally treated mixture and further hydrothermally treated in the second step at 170 ° C. for 10 hours. Got. Added silica sol Al₂O_ThreeThe molar oxide ratio to SiO₂/ Al₂O_ThreeThe ratio was 0.10. As a result of X-ray diffraction, this powder was an 8-membered ring SAPO having a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was 1.00. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 1.9 μm. The Si / Al atomic ratio of the entire crystal particles of the fired powder was 0.15, the Si / Al atomic ratio on the surface was 2.13, and the atomic ratio of Si / P on the surface was 3.01. Table 5 shows the reaction results 6 hours after starting the distribution of the raw materials. As is clear from this example, by further adding silica sol during the hydrothermal treatment, the hydrothermal treatment time at a temperature of 170 ° C. has a larger atomic ratio of Si / Al on the surface than that of Example 16, and dimethyl It was found that the amine selectivity was improved.
[0100]
Comparative Example 10
Hydrothermal treatment is performed at the temperature of the contents as the first step from 25 ° C to 115 ° C at 20 ° C / h, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The white calcined powder (84.7 g, catalyst yield) was obtained in the same manner as in Example 14 except that the temperature was raised and a part of the crystallization step of the first step and the second step were held at 170 ° C. for 5 hours. 80%). As a result of X-ray diffraction, this powder was a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was 0.98. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 2.5 μm. The obtained sintered powder had a Si / Al atomic ratio of 0.14 for the entire crystal particles, a surface Si / Al atomic ratio of 0.49, and a surface Si / P atomic ratio of 0.53. Further, from observation with a scanning transmission electron microscope, the crystal particles of the fired powder had an amorphous oxide layer with a thickness of 2.5 nanometers. Table 5 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0101]
Comparative Example 11
Hydrothermal treatment is performed at the temperature of the contents, as a first step from 25 ° C to 115 ° C at a rate of 20 ° C / h, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The white calcined powder (85.0 g, catalyst yield) was obtained in the same manner as in Example 14 except that a part of the first crystallization step and the second step were held at 170 ° C. for 175 hours. 80%). As a result of X-ray diffraction, this powder was an 8-membered ring SAPO having a pure shabasite-type structure, and no peak of the AFI-type structure, JCPDS No. 20-0045 compound was observed. The crystallinity was 1.01. The particle properties were cubic crystals and were well aligned in size and shape. The average particle size was 2.7 μm. The Si / Al atomic ratio of the entire crystal particles of the fired powder was 0.14, the Si / Al atomic ratio on the surface was 2.26, and the atomic ratio of Si / P on the surface was 3.13. Further, from observation with a scanning transmission electron microscope, the crystal particles of the fired powder had an amorphous oxide layer with a thickness of 25 nanometers. Table 5 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0102]
[Table 4]

[0103]
[Table 5]

[0104]
As is apparent from these examples, the 8-membered ring SAPO having the shabasite structure of the present invention has an amorphous oxide layer on the crystal grain surface where the Si / Al atomic ratio is larger than the whole crystal grain. I found it. In addition, the catalytic performance in the production of methylamines by the reaction of methanol and ammonia depends on the thickness of the amorphous oxide layer, the atomic ratio of the surface Si / Al measured by X-ray photoelectron spectroscopy, and the surface Si. It was also found that there is a correlation with the atomic ratio of / P. That is, as the amorphous oxide layer becomes thicker, the atomic ratio of Si / Al on the surface, and the atomic ratio of Si / P on the surface increase, the methanol conversion and trimethylamine selectivity decrease, and dimethylamine The selectivity is high. Shabasite-type SAPO having an amorphous oxide layer with a thickness in the range of 3 to 20 nanometers or an atomic ratio of Si / Al on the surface of 0.50 to It can be seen that shabasite SAPO in the range of 2.20 or shabasite type SAPO having a surface Si / P atomic ratio in the range of 0.55 to 3.10 exhibits excellent catalytic performance. The rate of change in the thickness and surface composition ratio of the amorphous oxide layer with the lapse of hydrothermal treatment time is TEAOH / Al₂O_ThreeMolar ratio or H₂O / Al₂O_ThreeThe amorphous oxide layer is thicker, the surface Si / Al atomic ratio, and the surface Si / P atomic ratio increase as the second stage time of hydrothermal treatment increases. It can be seen that the methanol conversion and trimethylamine selectivity are low. In the catalyst of Example 14, the reaction raw material was supplied at a space velocity (GHSV) of 1500 h.^-1Under the conditions of a temperature of 310 ° C and a pressure of 2 MPa, the methanol conversion at 1000 hours after starting the raw material distribution was 95 wt%, the monomethylamine selectivity was 37 wt%, the dimethylamine selectivity was 60 wt%, and the trimethylamine selectivity was 3 wt%. Lifetime performance is shown.
[0105]
4). SAPO-56 When SAPO-17 Between surface composition and thickness of amorphous oxide layer and catalyst performance
Examples 18 and 19 and Comparative Example 12 are examples relating to the surface composition and thickness of the amorphous oxide layer and the catalyst performance in SAPO-56 and SAPO-17 having eight oxygen-membered ring pores. Si / Al atomic ratio (bulk Si / Al atomic ratio), surface Si / Al atomic ratio, surface Si / P atomic ratio, amorphous oxide of the whole crystal grains of each example and comparative example The layer thicknesses are summarized in Table 6. The reaction test was conducted in the same manner as in Examples 1-9.
[0106]
Example 18
To a homogeneous mixture of 85% phosphoric acid (75.6 g) and pure water (256.6 g) and N, N, N ′, N′-tetramethyl-1,6-hexanediamine (113.0 g), pseudoboehmite (43.1 g: SASOL GERMANY GmbH, PURAL NF, Al₂O_Three77.5% content) was added with stirring. After the mixture was stirred for 1 hour, fumed silica (11.8 g: Nippon Aerosil Co., Ltd., AEROSIL-200) was added, and the mixture was further stirred for 30 minutes. The composition of this mixture in molar oxide ratio was as follows: 2.0TMHD: 1.0Al₂O_Three: 1.0P₂O_Five: 0.6SiO₂: 50H₂O (TMHD represents N, N, N ', N'-tetramethyl-1,6-hexanediamine). The obtained mixture was hydrothermally treated with stirring in a stainless steel autoclave. In the hydrothermal treatment, the temperature of the contents is raised from 20 ° C / h to 25 ° C to 115 ° C as the first step, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The temperature was raised at 170 ° C. and maintained at 170 ° C. for 75 hours as a part of the crystallization step of the first step and the second step. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged three times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 600 ° C. for 4 hours under an air stream to obtain a white powder. As a result of X-ray diffraction, this powder was SAPO-56 having pure 8-oxygen ring pores. The Si / Al atomic ratio of the entire crystal grains of the fired powder was 0.27, the Si / Al atomic ratio on the surface was 1.75, and the atomic ratio of Si / P on the surface was 2.71. From the observation with a scanning transmission electron microscope, the crystal particles of the fired powder had an amorphous oxide layer with a thickness of 10 nanometers. Table 6 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0107]
Example 19
To a uniform mixture of 85% phosphoric acid (52.0 g), pure water (176.6 g) and quinuclidine (37.6 g), pseudoboehmite (29.7 g: SASOL GERMANY GmbH, PURAL NF, Al₂O_Three77.5% content) was added with stirring. After this mixture was stirred for 1 hour, fumed silica (4.1 g: Nippon Aerosil Co., Ltd., AEROSIL-200) was added, and the mixture was further stirred for 30 minutes. The composition of this mixture in molar oxide ratio was as follows: 1.5Qn: 1.0Al₂O_Three: 1.0P₂O_Five: 0.3SiO₂: 50H₂O (Qn represents quinuclidine). The obtained mixture was hydrothermally treated with stirring in a stainless steel autoclave. In the hydrothermal treatment, the temperature of the contents is raised from 20 ° C / h to 25 ° C to 115 ° C as the first step, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The temperature was raised at 150 ° C. for 50 hours at 170 ° C. as part of the crystallization step of the first step and the second step. The pressure during the hydrothermal treatment was self-generated pressure. After cooling to room temperature, the autoclave was opened and the resulting slurry was centrifuged to obtain a precipitate. The obtained precipitate was washed and centrifuged three times with 200 ml of pure water, and then dried at 80 ° C. for 12 hours. Further, it was calcined at 600 ° C. for 4 hours under an air stream to obtain a white powder. As a result of X-ray diffraction, this powder was SAPO-17 having pure 8-oxygen ring pores. The Si / Al atomic ratio of the entire crystal grains of the fired powder was 0.11, the Si / Al atomic ratio on the surface was 1.01, and the atomic ratio of Si / P on the surface was 1.36. Further, from the observation with a scanning transmission electron microscope, the crystal particles of the fired powder had an amorphous oxide layer having a thickness of 5 nanometers. Table 6 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0108]
Comparative Example 12
Hydrothermal treatment is performed at the temperature of the contents, as a first step from 25 ° C to 115 ° C at a rate of 20 ° C / h, held at 115 ° C for 5 hours, and then from 115 ° C to 170 ° C at 20 ° C / h. The white calcined powder was obtained in the same manner as in Example 18 except that the temperature was raised at 1 ° C. and the second crystallization step was carried out at 170 ° C. for 5 hours. As a result of X-ray diffraction, this powder was SAPO-56 having pure 8-oxygen ring pores. The Si / Al atomic ratio of the entire crystal grains of the fired powder was 0.25, the Si / Al atomic ratio on the surface was 0.48, and the atomic ratio of Si / P on the surface was 0.51. Further, from observation with a scanning transmission electron microscope, the crystal particles of the fired powder had an amorphous oxide layer with a thickness of 2 nanometers. Table 6 shows the reaction results 6 hours after starting the distribution of the raw materials.
[0109]
As is apparent from these examples, even in the 8-membered ring SAPO having a structure other than the shabasite type, the amorphous oxide layer of the present invention in which the atomic ratio of Si / Al is larger than that of the entire crystal grain is reduced. It turns out that it has on the surface. In addition, these 8-membered ring SAPOs having an amorphous oxide layer with a preferred thickness or a surface composition ratio with a preferred range have excellent catalytic activity in the production of methylamines by the reaction of methanol and ammonia. It can also be seen that it exhibits dimethylamine selectivity.
[0110]
[Table 6]

[0111]
5). Example of disproportionation reaction using monomethylamine as a raw material
Example 20 and Comparative Example 13 are examples of a disproportionation reaction using monomethylamine as a raw material.
[0112]
Example 20
The reaction tube was charged with 2.5 g (volume 3.5 ml) of the catalyst synthesized in Example 6, and monomethylamine was GHSV3000h at a reaction pressure of 2 MPa and a temperature of 320 ° C.^-1The reaction was conducted at The results of the disproportionation reaction from monomethylamine to ammonia and dimethylamine at 6 hours after the start of the reaction were as follows.
Conversion of monomethylamine: 73 mol%
Dimethylamine selectivity: 99% by weight
Trimethylamine selectivity: 1% by weight
[0113]
Comparative Example 13
Using the catalyst synthesized in Comparative Example 8, a monomethylamine disproportionation reaction was performed in the same manner as in Example 20. The results at 6 hours after the start of the reaction were as follows.
Conversion of monomethylamine: 69 mol%
Dimethylamine selectivity: 98% by weight
Trimethylamine selectivity: 2% by weight
[0114]
Compared with the result of Comparative Example 13 using the catalyst of Comparative Example 8 synthesized according to the method of Catalyst Preparation Example 1 described in JP-A-2000-117114, the 8-membered ring SAPO having the shabasite type structure of Example 6 is As shown in Example 20, it was found that excellent performance was obtained even in the disproportionation reaction of monomethylamine.
[0115]
【The invention's effect】
As is apparent from the description using the examples and comparative examples above, the 8-membered ring SAPO of the present invention has an amorphous oxide layer in which the atomic ratio of silicon to aluminum is larger than that of the entire crystal grain. The molecular sieve has a catalytic activity superior to that of the prior art in the production of methylamines by the reaction of methanol and ammonia, the disproportionation reaction of monomethylamine, etc., which are carried out industrially. Shows dimethylamine selectivity. The thickness and surface composition of the amorphous oxide layer have a great influence on the catalyst performance, but can be easily controlled by the synthesis conditions of the catalyst of the present invention. Further, according to the method for producing 8-membered ring SAPO of the present invention, 8-membered ring SAPO having high purity and crystallinity can be produced with a small amount of templating agent, which has been difficult to synthesize conventionally. Therefore, since both raw material costs and waste disposal costs can be reduced as compared with the prior art, a catalyst can be produced efficiently at low cost. Moreover, since there is little waste, it can also contribute to the reduction of environmental burden. Therefore, the industrial value of the crystalline silicoaluminophosphate molecular sieve having eight oxygen member ring pores and the production method thereof and the production method of methylamines provided by the present invention is extremely large.
[Brief description of the drawings]
1 is a scanning transmission electron microscope image of the catalyst of Example 14 (× 80,000 times). FIG.
2 is an enlarged image (× 1 million times) of the left-most white frame in FIG.
3 is an electron diffraction image of a portion where the lattice pattern of FIG. 2 can be seen.
4 is an electron diffraction image of a white layer in which the lattice pattern of FIG. 2 is not seen.

Claims (22)

A crystalline silicoaluminophosphate molecular sieve having an eight-membered ring pore having an amorphous oxide layer mainly composed of an oxide containing silicon, aluminum, and phosphorus on the crystal particle surface, The atomic ratio of silicon to aluminum in the amorphous oxide layer measured by X-ray photoelectron spectroscopy is in the range of 0.50 to 2.20, and the atomic ratio of the whole crystal particles measured by ICP analysis also rather large atomic ratio of silicon to phosphorus of the amorphous oxide layer as measured by X-ray photoelectron spectroscopy, characterized in that in the range of 0.55 to 3.10, 8 oxygen-membered ring pores Crystalline silicoaluminophosphate molecular sieve with.   The crystalline silicoaluminophosphate molecular sieve having eight-membered ring pores according to claim 1, wherein the thickness of the amorphous oxide layer on the surface of the crystal particles is in the range of 3 to 20 nanometers. The crystalline silicoaluminophosphoric acid having eight-membered ring pores according to claim 1 or 2 , further comprising one or more elements selected from magnesium, yttrium, titanium, zirconium, manganese, iron, cobalt, and tin. Salt molecular sieve. The crystalline silicoaluminophosphate having 8-membered ring pores according to any one of claims 1 to 3 , wherein the shape of the crystal particles is a rectangular parallelepiped and / or a cubic shape, and the average particle diameter is 5 µm or less. Molecular sieve. The structure of the main body part of the crystal grain excluding the amorphous oxide layer on the crystal grain surface from the whole crystal grain is a shabasite type and has 8 oxygen ring ring pores according to any one of claims 1 to 4. Crystalline silicoaluminophosphate molecular sieve. The ratio of the peak intensity of the (100) plane of AFI structure body to the peak intensity of the (100) plane of the X-ray chabazite structure measured by diffraction is 0.02 or less, chabazite of claim 5, wherein A crystalline silicoaluminophosphate molecular sieve having 8 oxygen-membered ring pores. A raw material mixture containing an organic amine and / or an organic ammonium salt, an aluminum compound, a phosphorus compound, a silicon compound, and water is hydrothermally treated to have an 8-oxygen ring pore having an amorphous oxide layer on the crystal particle surface. In producing a crystalline silicoaluminophosphate molecular sieve, a first step for generating at least a crystalline portion thereof, and a second step for forming an amorphous oxide layer on the crystal grain surface by further hydrothermal treatment A method for producing a crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores according to any one of claims 1 to 6 . The hydrothermal treatment of the first step includes two steps of a hydrothermal treatment for 1 hour or more within a temperature range of 80 to 130 ° C and a hydrothermal treatment for 1 to 10 hours within a temperature range of 150 to 200 ° C. A method for producing a crystalline silicoaluminophosphate molecular sieve having eight-membered ring pores according to claim 7 . Of the hydrothermal treatment of the first step, the step of hydrothermal treatment for 1 hour or more within the temperature range of 80 to 130 ° C is a step of raising the temperature between 80 to 130 ° C over 1 hour or between 80 to 130 ° C The method for producing a crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores according to claim 8 , comprising a step of maintaining the constant temperature of 1 hour or more. The crystalline silicon having 8-membered ring pores according to any one of claims 7 to 9 , wherein the hydrothermal treatment of the second step includes a step of hydrothermal treatment for 10 hours or more within a temperature range of 150 to 200 ° C. Method for producing aluminophosphate molecular sieve. The hydrothermal treatment of the first step includes two steps of a hydrothermal treatment for 3 to 24 hours at a constant temperature of 95 to 125 ° C and a hydrothermal treatment for 1 to 10 hours within a temperature range of 150 to 200 ° C. The crystalline silicoaluminophosphoric acid having 8-membered ring pores according to claim 7 , wherein the hydrothermal treatment in the second step includes a hydrothermal treatment in a temperature range of 150 to 200 ° C for 10 to 150 hours. A method for producing a salt molecular sieve. Total moles of organic amine and organic ammonium salt with respect to the number of moles of aluminum compound converted to Al ₂ O ₃ in the raw material mixture containing organic amine and / or organic ammonium salt, aluminum compound, phosphorus compound, silicon compound, and water The method for producing a crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores according to any one of claims 7 to 11 , wherein the number ratio is in the range of 0.4 to 0.98. The method for producing a crystalline silicoaluminophosphate molecular sieve having 8-oxygen ring pores according to any one of claims 7 to 12 , wherein the organic amine and / or organic ammonium salt is tetraethylammonium hydroxide. The method for producing a crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores according to any one of claims 7 to 13 , wherein the aluminum compound is pseudoboehmite. The method for producing a crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores according to any one of claims 7 to 14 , wherein the phosphorus compound is phosphoric acid. The method for producing a crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores according to any one of claims 7 to 15 , wherein the silicon compound is silica sol. The method for producing a crystalline silicoaluminophosphate molecular sieve having 8-membered ring pores according to any one of claims 7 to 16 , wherein a silicon compound is further added before or during the second step. The crystalline material having eight-membered ring pores according to any one of claims 7 to 17 , further comprising one or more elements selected from magnesium, yttrium, titanium, zirconium, manganese, iron, cobalt, and tin. Manufacturing method of silicoaluminophosphate molecular sieve. The crystalline silicoaluminophosphate having an 8-oxygen ring pore according to any one of claims 7 to 18, wherein the crystalline silicoaluminophosphate molecular sieve having an 8-oxygen ring pore is a shabasite type. Manufacturing method of molecular sieve. A method for producing methylamines, wherein methanol and ammonia are reacted in the presence of the crystalline silicoaluminophosphate molecular sieve having eight oxygen-membered ring pores according to any one of claims 1 to 6 . A process for producing methylamines, wherein methanol and monomethylamine are reacted in the presence of the crystalline silicoaluminophosphate molecular sieve having eight oxygen-membered ring pores according to any one of claims 1 to 6 . A method for producing methylamines, wherein a disproportionation reaction of monomethylamine is carried out in the presence of the crystalline silicoaluminophosphate molecular sieve having eight oxygen-membered ring pores according to any one of claims 1 to 6 .

Images