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WO2010029087A1 - Procédé de production de méthylamines - Google Patents

Procédé de production de méthylamines Download PDF

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Publication number
WO2010029087A1
WO2010029087A1 PCT/EP2009/061652 EP2009061652W WO2010029087A1 WO 2010029087 A1 WO2010029087 A1 WO 2010029087A1 EP 2009061652 W EP2009061652 W EP 2009061652W WO 2010029087 A1 WO2010029087 A1 WO 2010029087A1
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WO
WIPO (PCT)
Prior art keywords
column
alkali metal
distillation
ammonia
methanol
Prior art date
Application number
PCT/EP2009/061652
Other languages
German (de)
English (en)
Inventor
Karl-Heinz Ross
Wolfgang Schwarz
Original Assignee
Basf Se
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Basf Se filed Critical Basf Se
Publication of WO2010029087A1 publication Critical patent/WO2010029087A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/04—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups
    • C07C209/14—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups by substitution of hydroxy groups or of etherified or esterified hydroxy groups
    • C07C209/16—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups by substitution of hydroxy groups or of etherified or esterified hydroxy groups with formation of amino groups bound to acyclic carbon atoms or to carbon atoms of rings other than six-membered aromatic rings

Definitions

  • the invention relates to a process for preparing methylamines by continuous reaction of methanol with ammonia and subsequent continuous distillative separation of the resulting product stream (10) containing monomethylamine, dimethylamine, trimethylamine, ammonia and methanol as components into at least four columns [(1)]. to (4)], wherein the second (2) and / or third column (3) alkali metal hydroxide is added.
  • the reaction product i. the product stream of a continuous reaction, i.d.R. the product gas stream of a continuous reaction
  • the product (gas) stream is separated into the individual components.
  • TMA trimethylamine
  • MMA monomethylamine
  • DMA dimethylamine
  • the third column is followed by another, fifth column.
  • the methanol obtained in the other fifth column is advantageous, as well as the ammonia separated in the first column, again fed to the methylamine synthesis.
  • the distillation columns Due to the aggressiveness of components in the product stream, the distillation columns, preferably made of carbon steel, corrode.
  • alkali metal hydroxide is added to the feed of the first column in order to prevent corrosion in alkylamine plants.
  • blockages on the trays of the first column occur after a short time.
  • WO 05/030697 A1 (BASF AG) describes a process for preventing corrosion in the separation of methylamines from a in the production of methylamines by gas phase reaction of methanol and ammonia resulting monomethyl, dimethylamine, trimethylamine, ammonia and methanol ent components - holding product stream (10), in at least four columns [(1) to (4)], wherein the second (2) or third column (3) alkali metal hydroxide is added.
  • the object of the present invention was to remedy the disadvantages of the prior art in the case of the methylamine preparation process, and in particular to provide an improved process for preventing corrosion in the columns of the distillation plant and possibly the exhaust gas treatment plant in the production of methylamines.
  • problems caused by under- or over-dosing of alkali metal hydroxide should be avoided.
  • the solution according to the invention consists of adding alkali metal hydroxide to the second (2) and / or third column (3) and optionally columns of the exhaust gas treatment plant, the amount of which is specifically dimensioned.
  • adding the alkali metal hydroxide of the third column (3), esp. In the feed to the third column it turns out that even in the first (1) and second column (2) no corrosion occurs, although there are aggressive media contained in the gas stream .
  • the formation of blockages in the first and second column is even more advantageously avoided by the solution according to the invention.
  • both blockages in the columns by unwanted by-products and harmful corrosion in the system by an under- or overdosing of alkali metal hydroxide are avoided.
  • a particularly economical dosage of the alkali metal hydroxide is achieved by the method according to the invention.
  • the product (gas) stream is fed to a distillation unit.
  • the product (gas) stream is fed in a side feed to a first distillation column.
  • ammonia is separated by distillation.
  • the distillation takes place at a pressure of preferably 15 to 20 bar and in particular at a pressure of 15 to 18 bar.
  • the present as an azeotrope with trimethylamine separated ammonia is withdrawn through the top of the first column and preferably fed again to the Methylaminher ein.
  • the remaining constituents of the product gas stream form the bottom and are withdrawn from the column and fed to a second column (2).
  • the feed of the second column is also formed as a side feed.
  • In the second column is separated by an extractive distillation with the addition of water trimethylamine.
  • the trimethylamine is withdrawn via the top of the second column.
  • the sump-forming residual components of the product gas stream are fed in a side feed to a third column (3).
  • About the bottom of the third column the water used for extractive distillation in the second column and the water formed in the reaction, and unreacted methanol are withdrawn. Over the top of the third column, a mixture of monomethylamine and dimethylamine is withdrawn.
  • the distillation in the third column is preferably carried out at a pressure of 7 to 15 bar and in particular at a pressure of 8 to 12 bar.
  • the withdrawn over the top of the third column mixture of monomethylamine and dimethylamine is fed in a side feed to a fourth column (4).
  • the stream of monomethylamine and dimethylamine is separated distillatively at a pressure of preferably 6 to 10 bar and in particular at a pressure of 7 to 9 bar.
  • Dimethylamine is precipitated preferably in the bottom of the fourth column and monomethylamine is withdrawn via the top of the fourth column.
  • the dimethylamine obtained in the fourth column (4) after distilling off monomethylamine is further purified by distillation in a sixth column (6).
  • the dimethylamine is preferably fed to the sixth column as side feed and preferably removed as a top hat.
  • the further purification by separation of secondary components in particular in the ppm range, such as.
  • methylethylamine and / or bis-dimethylamino-methane As methylethylamine and / or bis-dimethylamino-methane.
  • the dimethylamine is obtained by the purification in the sixth column in a purity of in particular> 99.8 wt .-%, more preferably> 99.95 wt .-%, to.
  • the distillation in the sixth column is preferably carried out at a pressure in the range of 6 to 10, in particular 7 to 9, bar.
  • a fifth column (5) can be used, to which the methanol-containing water is fed from a side draw of the third column.
  • the methanol is separated by distillation.
  • the methanol is withdrawn via the top of the fifth column and preferably fed again to the reaction.
  • the methanol purified as the bottoms of the fifth column is preferably recycled back to the third column.
  • the heating of the columns is preferably carried out by steam at a pressure of preferably 10 to 20 bar and in particular a pressure in the range of 12 to 17 bar in the bottom of the columns.
  • the columns used for the distillation are preferably tray columns.
  • column trays are all known in the art types.
  • packed columns or packed columns In addition to soil columns, it is also possible to use packed columns or packed columns. Any desired filler geometry known to those skilled in the art can be used here.
  • the transport of the product stream through the column cascade is preferably carried out due to the pressure difference between the individual columns.
  • alkali metal hydroxides are sodium hydroxide and potassium hydroxide, preferably sodium hydroxide.
  • the alkali metal hydroxide can be added in solid form as a salt or preferably as an aqueous solution.
  • an aqueous alkali metal hydroxide solution this preferably has a concentration of in the range of 5 to 35 wt .-%, especially in the range of 15 to 30 wt .-%, z. B. 25 wt .-%, on.
  • the amount of alkali metal hydroxide must be such that unreacted alkali metal hydroxide is present in the bottom of the third column and optionally in the bottom of the desorption column of the exhaust gas treatment plant.
  • the amount of alkali metal hydroxides added can be more advantageously dimensioned such that a certain amount of alkali metal hydroxide is present in the bottom of the third column and optionally in the bottom of the desorption column. It has surprisingly been found that it is not sufficient to design the addition of the alkali metal hydroxide only in such a way that alkali metal hydroxide is present at all in the bottom of the third column and optionally in the bottom of the desorption column. Rather, according to the invention, a slightly higher excess of the alkali metal hydroxide must be used in order to achieve the desired effects, in particular the even more effective and advantageous prevention of corrosion.
  • alkali metal hydroxide Too high an addition amount of alkali metal hydroxide is, as was recognized according to the invention, also unfavorable. There is overdose of alkali metal hydroxide the risk of tepid corrosion in the bottom of the third column and possibly in the bottom of the desorption column, where due to the process temperatures up to 185 0 C, especially up to 210 0 C, may occur. Especially in the evaporator of the third column and, if appropriate, the desorption column, easily harmful alkali concentrations can arise due to concentration effects.
  • the determination of the excess alkali metal hydroxide in the bottom of the third column (3) and optionally in the bottom of the desorption column must take into account according to the invention that in addition to hydroxide also carbonate ions are present, which arise from the bound by the alkali metal hydroxide CO2 (by-product from the reactor).
  • Titrating a sample of the bottom of the third column with mineral acid, eg., hydrochloric acid (HCl) the acid consumption can be due both to the reaction of hydroxide ions (OH) and carbonate ions (CO3 2 -).
  • the problem can be solved by a titration with different endpoints.
  • the dosage of alkali metal hydroxide is such that a measurement of the Alkalimetallhydroxidüberschusses in the bottom of the third column and the bottom of the desorption column at a per analysis of 20 g bottom product according to the above method a 2 "P - M - value of at least 2 ml, and at most 20 ml.
  • this value is in the range of 2.5 to 6 ml, more preferably in the range of 3 to 5 ml, most preferably in the range of 3 to 4 ml.
  • the process for preparing methylamines is accordingly additionally characterized in that exhaust gases produced in the process are worked up in a water-operated absorption column and subsequent desorption column for the recovery of ammonia and / or methylamines and / or the recovered ammonia and or methylamine is recycled to the reaction of methanol, wherein the desorption column of alkali metal hydroxide is added, the amount of which is such that for the bottom of the desorption column is that for a 20 g sample of this sump 2 « P - M in the range of 2 to 20 ml, where P is the consumption of aqueous 0.1 molar hydrochloric acid in ml in a titration of the sample against phenolphthalein as an indicator and M the total consumption of aqueous 0.1 molar hydrochloric acid in ml after the subsequent continued titration of the sample against methyl red as an indicator.
  • the alkali metal hydroxide may already be added to the bottom of the absorption column or to the bottom of the desorption column or preferably to the inlet of the desorption column.
  • alkali metal hydroxides are sodium hydroxide and potassium hydroxide, preferably sodium hydroxide.
  • the alkali metal hydroxide can be added in solid form as a salt or preferably as an aqueous solution.
  • an aqueous alkali metal hydroxide solution preferably has a concentration of in the range of 5 to 35 wt .-%, especially in the range of 15 to 30 wt .-%, z. B. 25 wt .-%, on.
  • ammonia- and / or methylamine-containing exhaust gases from other processes for the recovery of ammonia and / or methylamines can additionally be processed in the absorption column and subsequent desorption column.
  • the absorption column is preferably operated at an absolute pressure in the range of 1 to 5 bar, especially 2 to 4 bar, a bottom temperature in the range of 20 to 50 0 C and a top temperature in the range of 15 to 30 0 C.
  • the exhaust gas of the absorption column is preferably fed to a combustion plant.
  • the desorption column is preferably operated at an absolute pressure in the range of 10 to 18 bar, especially 12 to 16 bar, a bottom temperature in the range of 180 to 210 0 C and a top temperature in the range of 35 to 70 0 C.
  • Absorption columns and desorption columns which can be used in the process according to the invention are standard apparatuses which are widely used in process engineering (for example: Chemical Engineers 'Handbook, 4th Ed., Editor: JH Perry, McGraw-Hill Book Comp., Chapter, Gas Absorption'). , 14-2 ff.).
  • Preferred columns are firstly for the absorption: packed column with liquid feed, and secondly for the desorption: tray column.
  • the reaction of methanol with ammonia preferably takes place in the gas phase and preferably in the presence of an aluminum oxide-containing catalyst, in particular a catalyst according to WO 2007/036478 A1 (BASF AG).
  • FIG. 1 and FIG. 2 each show an embodiment of a distillation plant for methylamine distillation formed according to the invention.
  • the distillation plant for methylamine distillation comprises according to FIG. 1 five columns and according to FIG. 2 six columns.
  • a product gas stream 10 obtained in the reaction of ammonia and methanol to form methylamines is fed to a first column 1 via a side feed.
  • ammonia which is present as an azeotrope with trimethylamine, separated from the product stream by distillation.
  • About the top of the first column 1 ammonia 1 1 is withdrawn and fed again to the methylamine synthesis.
  • the remaining components of the product stream 10 fall as the bottom 12 of the first column. 1 at.
  • the bottom 12 of the first column 1 is fed via a side feed to a second column 2.
  • trimethylamine is separated from the sump 12 of the first column 1 by extractive distillation.
  • water 13 is added to the second column 2 via a second side feed.
  • the second side inlet is above the inlet for the bottom 12 of the first column 1.
  • trimethylamine 14 is withdrawn.
  • the remaining components accumulate in the sump 15 of the second column 2.
  • the sump 15 of the second column 2 is fed as feed 17 to a third column 3.
  • Leach 16 is added to feed 17.
  • the liquor 16 can also be fed into the sump 15 or into the stripping section of the second column 2.
  • the lye 16 is an alkali metal hydroxide, in particular sodium hydroxide or potassium hydroxide, in each case in aqueous solution.
  • the third column 3 2 monomethylamine and dimethylamine is separated by distillation from the sump 15 of the second column.
  • the monomethylamine and dimethylamine is withdrawn as overhead stream 18 via the top of the third column 3 and fed to a fourth column 4.
  • water, methanol and other reaction by-products are included.
  • the third column 3 can be followed by a fifth column 5.
  • the fifth column 5 is fed via an inlet 20 methanolhal- tiges water from the third column 3.
  • methanol is separated from the water in the fifth column 5.
  • the water purified by methanol is recycled via a return line 21 back into the third column 3.
  • the separated methanol 22 is withdrawn and fed again to the methylamine synthesis. From the bottom of the third column 3 of methanol purified wastewater 19 is withdrawn.
  • Monomethylamine 24 is withdrawn via the top of the fourth column 4. From the bottom of the fourth column 4 accumulating dimethylamine 23 is withdrawn.
  • the bottom stream 23 of the fourth column 4, which in particular contains dimethylamine, is further purified in the sixth column 6.
  • Dimethylamine is withdrawn via the top of the sixth column 6 (stream 25).
  • About the bottom 26 of the sixth column 6 by-products such.
  • methylethylamine and / or bis-dimethylamino-methane deducted.
  • a resulting in the synthesis of methylamine product stream of 50 t / h was separated.
  • the columns were heated by steam at a pressure of 16 bar.
  • From the product stream was in a first column at a pressure of 16.5 bar ammonia, which is present as an azeotrope with trimethylamine, separated.
  • the remaining product stream was fed to a second column.
  • In the second column was separated at a pressure of 14 bar at a bottom temperature of 160 0 C and a top temperature of 103 0 C trimethylamine and withdrawn through the top of the second column.
  • the bottom of the second column was fed to a third column, wherein 150 kg / h aqueous 25 wt .-% sodium hydroxide solution was added to the feed.
  • the third column was operated at a pressure of 9 bar with a bottom temperature of 181 0 C and a head temperature of 70 0 C above the head dimethylamine and mono- withdrawn methylamine.
  • the monomethylamine and dimethylamine was separated in a fourth column at a pressure of 7.5 bar with a bottom temperature of 74 0 C and a top temperature of 53 0 C. Monomethylamine was withdrawn via the top of the fourth column and dimethylamine via the bottom of the fourth column.
  • the resulting as the bottom of the third column methanol-containing water was fed via a side draw at the foot of the third column in vapor form a fifth column, operating at a pressure of 8.3 bar with a bottom temperature of 170 0 C and a head temperature of 165 0 C.
  • Methanol was withdrawn via the top of the fifth column.
  • the methanol-purified water was returned to the third column from the bottom of the fifth column.
  • a value of 3.5 ml was obtained from the 2 ' P - M value determination of 20 g of the column bottom of the third column.
  • the bottom of the third column was colorless. There was no corrosion in the columns.
  • the methylamine distillation was carried out under the same conditions as in Example 1, but the metered amount of 25% strength by weight sodium hydroxide solution in the feed of the third column was only 65 kg / h.
  • the 2 " P-M value determination of 20 g of the column bottom of the third column resulted in a value of 1.6 ml.
  • the bottoms discharge of the column was markedly yellowish (up to 80 APHA (according to DIN ISO 6271)).

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé de production de méthylamines par réaction continue du méthanol avec l'ammoniac puis séparation par distillation continue du flux de produit obtenu constitué de monométhylamine, de diméthylamine, de triméthylamine, d'ammoniac et de méthanol, procédé selon lequel l'ammoniac est séparé par distillation dans une première colonne; les constituants résiduels du flux de produit obtenus en bas de colonne sont acheminés vers une deuxième colonne, dans laquelle la triméthylamine est séparée par distillation extractive avec apport d'eau; les autres constituants du flux de produit obtenus en bas de la deuxième colonne sont acheminés vers une troisième colonne, dans laquelle la monométhylamine et la diméthylamine sont séparées, puis la monométhylamine et la diméthylamine sont séparées par distillation dans une quatrième colonne, une certaine quantité d'hydroxyde de métal alcalin étant ajoutée à la deuxième et/ou troisième colonne. La quantité d'hydroxyde de métal alcalin ajoutée est mesurée de sorte que, pour un échantillon de 20 g du produit obtenu en bas de la troisième colonne, 2•P – M soit compris entre 2 et 20 ml, P représentant la consommation d'acide chlorhydrique aqueux de concentration molaire égale à 0,1 en ml lors d'un titrage de l'échantillon réalisé en présence de phénolphtaléine comme indicateur et M représentant la consommation totale d'acide chlorhydrique aqueux de concentration molaire égale à 0,1 en ml après le titrage de l'échantillon réalisé ensuite en continu en présence de méthylrouge comme indicateur.
PCT/EP2009/061652 2008-09-12 2009-09-08 Procédé de production de méthylamines WO2010029087A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP08164284.5 2008-09-12
EP08164284 2008-09-12
EP09162721 2009-06-15
EP09162721.6 2009-06-15

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WO2010029087A1 true WO2010029087A1 (fr) 2010-03-18

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112745228A (zh) * 2020-12-30 2021-05-04 天津天南同创科技发展有限公司 一种高纯一甲胺、二甲胺的节能分离工艺装置及方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005030697A1 (fr) * 2003-09-24 2005-04-07 Basf Aktiengesellschaft Procede pour eviter la corrosion

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005030697A1 (fr) * 2003-09-24 2005-04-07 Basf Aktiengesellschaft Procede pour eviter la corrosion

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112745228A (zh) * 2020-12-30 2021-05-04 天津天南同创科技发展有限公司 一种高纯一甲胺、二甲胺的节能分离工艺装置及方法

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