KR101824472B1 - A three-way catalyst comprising a thin layer having precious metal components - Google Patents
A three-way catalyst comprising a thin layer having precious metal components Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 62
- 239000010970 precious metal Substances 0.000 title description 4
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 39
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 25
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 23
- 229910000629 Rh alloy Inorganic materials 0.000 claims abstract description 11
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 8
- 239000010948 rhodium Substances 0.000 abstract description 64
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 abstract description 36
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 abstract description 23
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 abstract description 12
- 239000010410 layer Substances 0.000 description 60
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 25
- 239000011248 coating agent Substances 0.000 description 12
- 238000000576 coating method Methods 0.000 description 12
- 229910045601 alloy Inorganic materials 0.000 description 9
- 239000000956 alloy Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 239000007789 gas Substances 0.000 description 9
- 238000005275 alloying Methods 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 238000001179 sorption measurement Methods 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 4
- QQONPFPTGQHPMA-UHFFFAOYSA-N Propene Chemical compound CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 4
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- XSKIUFGOTYHDLC-UHFFFAOYSA-N palladium rhodium Chemical compound [Rh].[Pd] XSKIUFGOTYHDLC-UHFFFAOYSA-N 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 239000011232 storage material Substances 0.000 description 4
- 230000009257 reactivity Effects 0.000 description 3
- 239000002356 single layer Substances 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 229910052878 cordierite Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
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- 229910052809 inorganic oxide Inorganic materials 0.000 description 2
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- 239000001294 propane Substances 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- VCUFZILGIRCDQQ-KRWDZBQOSA-N N-[[(5S)-2-oxo-3-(2-oxo-3H-1,3-benzoxazol-6-yl)-1,3-oxazolidin-5-yl]methyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C1O[C@H](CN1C1=CC2=C(NC(O2)=O)C=C1)CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F VCUFZILGIRCDQQ-KRWDZBQOSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000009924 canning Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- -1 for example Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 239000012041 precatalyst Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
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- 239000002904 solvent Substances 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/42—Platinum
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/44—Palladium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/46—Ruthenium, rhodium, osmium or iridium
- B01J23/464—Rhodium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
본 발명은 귀금속 성분으로서 Rh 또는 Pd-Rh 합금이 포함되는 박층을 가지는 삼원촉매에 관한 것이고, 백금, 팔라듐 및 로듐 성분이 포함된 하층 및 귀금속으로서 Rh 또는 Pd-Rh 합금이 박막의 상층으로 포함되는 삼원촉매에 관한 것이고, 본 발명에 의한 촉매는 박층 부재 촉매와 비교하여 THC, CO 및 NOx 배출에 있어서 향상된 결과를 주며, 따라서 동량의 귀금속을 사용하되, 귀금속의 일부를 박층으로 도포한다면 삼원촉매의 성능은 크게 향상된다.The present invention relates to a three-way catalyst having a thin layer in which Rh or a Pd-Rh alloy is contained as a noble metal component, and a lower layer containing platinum, palladium and rhodium components and an upper layer of Rh or Pd- Catalysts according to the present invention provide improved results in THC, CO and NOx emissions compared to thin layer catalysts, so that if the same amount of noble metal is used and a portion of the noble metal is applied as a thin layer, Performance is greatly improved.
Description
본 발명은 Rh 또는 Pd-Rh의 귀금속 성분이 담지된 박층이 통상의 삼원촉매 상층으로서 구성되는 삼원촉매에 관한 것이고, 더욱 상세하게는 백금, 팔라듐 및 로듐 성분이 포함된 하층 및 Rh 성분 또는 Pd-Rh 합금이 포함된 박막의 상층으로 이루어진 삼원촉매에 관한 것이다.The present invention relates to a three-way catalyst in which a thin layer on which a noble metal component of Rh or Pd-Rh is deposited is constituted as an upper layer of a conventional three-way catalyst. More specifically, the present invention relates to a three-way catalyst comprising a lower layer containing Rh, platinum, Rh alloy. ≪ / RTI >
삼원촉매는 자동차 배기가스 중 CO와 HC를 산화반응으로 NOx를 환원반응으로 이들 유해 성분들을 저감시킨다. 촉매 본체는 세라믹으로 만들어진 기재(substrate)와, 기재에 도포되는 Al2O3 워시코트로 구성되고, 워시코트는 알루미나에 담지된 귀금속 성분들을 포함한다. 삼원촉매에서 귀금속은 성분들은 Pt, Rh 및 팔라듐(Pd)을 포함한 Pt/Pd/Rh의 삼원귀금속계가 사용된다. Pt는 주로 CO와 HC를 저감시키는 산화반응을 촉진시키고 Rh는 NOx 반응을 촉진시킨다. Pd는 CO와 HC light-off(반응개시 온도)에 유리하나 NOx 반응과 sulfur poisoning(연료 중에 포함되어 있는 유황성분에 의한 성능저하)에 불리하다고 알려져 있다. 실무적으로 상기 삼원촉매 성능 최적화를 위하여 귀금속 성분들에서 Pd와 Rh 성분은 각각 별개의 성분으로 존재할 수 있다. 즉, Pd 및 Rh 성분들이 합금을 이루지 못하도록 개별 성분으로 삼원촉매에 배치될 수 있고, 예컨대, Pd 및 Rh은 이중층으로 존재하여 서로 합금화를 피하거나, 단일층을 존재하는 경우에도 각각의 지지체에 별도로 존재하도록 구성된다. 이러한 종래 개념과 달리, 본 출원인은, 최근 Pd-Rh 합금화를 통하여 삼원촉매 성능이 크게 개선된다는 것을 확인하였다. 즉, 결정성 Pd-Rh 합금을 포함하는 지지된 촉매는 Pd-Rh 합금화를 통한 삼원촉매 성능 향상 가능성을 제시하였다.Three-way catalyst reduces NOx by reduction reaction of CO and HC in automobile exhaust gas and reduces these harmful components. The catalyst body is composed of a ceramic substrate and an Al 2 O 3 washcoat applied to the substrate, and the wash coat comprises noble metal components supported on alumina. In the three-way catalyst, the precious metal components Pt, Rh and Pt / Pd / Rh including the palladium (Pd) are used. Pt promotes oxidation reactions that mainly reduce CO and HC, and Rh promotes NOx reaction. Pd is advantageous for CO and HC light-off (reaction initiation temperature) but it is known to be disadvantageous for NOx reaction and sulfur poisoning (performance degradation due to the sulfur component contained in fuel). Practically, Pd and Rh components in the noble metal components may exist as separate components in order to optimize the three-way catalyst performance. That is, the Pd and Rh components may be disposed in the three-way catalyst as discrete components so that they do not form an alloy, for example, Pd and Rh exist as a bilayer and avoid alloying each other, Lt; / RTI > Unlike this conventional concept, the Applicant has recently confirmed that the three-way catalyst performance is greatly improved through Pd-Rh alloying. That is, the supported catalyst containing the crystalline Pd-Rh alloy showed the possibility of improving the performance of the three-way catalyst through Pd-Rh alloying.
그러나, 강화되는 배기가스 규제 대응을 위하여 HC 라이트 오프 (light off) 개선이 여전히 요구되고, 특히 저온에서 촉매 활성 향상에 대한 필요성이 제기된다. 상기된 바와 같이 삼원촉매에서 NO 경우 HC, CO와 경쟁 흡착하므로, 촉매 활성점에 NO가 흡착하게 됨에 따른 HC, CO 흡착/반응이 낮아진다는 점 및 자동차 배기가스 정화용 촉매에서 활성물질로 사용되는 귀금속 중 Rh이 질소산화물(NOx) 환원에 우수하므로 NOx에 대한 제거를 우선적으로 진행하여 HC, CO에 대한 흡착점을 유지한다면, 반응성이 개선될 것이라는 기술적 근거에 따라 본 발명을 완성하게 되었다.However, HC light-off improvement is still required for enhanced exhaust gas control response, and a need for catalyst activity improvement at low temperatures is raised. As described above, in the case of NO in the case of NO in the case of NO, it is competitive with HC and CO, so that the adsorption / reaction of HC and CO due to adsorption of NO on the catalytic active site is lowered, and that the precious metal The present invention has been completed on the technical basis that the reactivity will be improved if the adsorption point for HC and CO is maintained by preferentially proceeding to remove NOx.
본 발명자들은 놀랍게도 백금, 팔라듐, 및 로듐 성분을 가지는 삼원촉매에 있어서, 최외각 층, 즉, 배기가스와 일차적으로 접촉되는 상층에 Rh 성분 또는 Pd-Rh 합금 성분이 포함된 단층을 박막 형태로 배치하면 삼원촉매 성능이 크게 개선된다는 것을 확인하였다.The present inventors have surprisingly found that in a three-way catalyst having platinum, palladium and rhodium components, a monolayer containing Rh component or Pd-Rh alloy component in the outermost layer, that is, the upper layer which is in primary contact with the exhaust gas, It was confirmed that the three - way catalyst performance was greatly improved.
본 발명은 귀금속 성분이 주성분인 박층을 포함하는 삼원촉매에 관한 것으로, Pt, Pd 및 Rh 성분들로 이루어진 귀금속 성분들을 가지는 하층 및 귀금속 성분들로는 Rh 성분 또는 Pd-Rh 합금의 박층인 상층으로 구성된다. 비-제한적으로 본 발명에 의한 삼원촉매에서 하층 및 상층의 Rh 성분들의 중량비는 5:95 내지 95:5인 것을 특징으로 하고, 바람직하게는 상기 상층의 두께는 3 내지 40um의 박층이고, 최적 코팅량은 10 내지 70g/L인 것을 특징으로 한다. 본 발명에 의한 삼원촉매 하층은 Pd 및 Rh 성분들이 합금을 형성하지 않는 경우 및 최근 본 출원인에 의해 성능 향상이 확인된 Pd 및 Rh 성분들이 합금을 형성하는 경우 모두의 구성을 포함한다. The present invention relates to a three-way catalyst comprising a noble metal component as a main component, and comprises a lower layer having noble metal components composed of Pt, Pd and Rh components and an upper layer comprising a Rh component or a thin layer of Pd-Rh alloy as noble metal components . Non-limitingly, in the three-way catalyst according to the present invention, the weight ratio of Rh components in the lower and upper layers is in the range of 5:95 to 95: 5, preferably the upper layer is a thin layer of 3 to 40 um, And the amount is 10 to 70 g / L. The three-way catalytic lower layer according to the present invention includes both the case where the Pd and Rh components do not form an alloy and the case where both the Pd and Rh components confirmed to have improved performance by the present applicant form an alloy.
본 발명은 귀금속 성분이 포함된 박층을 포함하는 촉매 본체 제조방법으로서, (i) Pt/Pd 함침 지지체, 및 Rh 함침 지지체를 생성하는 단계 (ii) 상기 함침 지지체들과 첨가제를 혼합하여 슬러리 워시코트를 제조하는 단계; (iii) 상기 슬러리 워시코트를 기재 (substrate)에 코팅하여 하층을 제조하는 단계; 및 (iv) 상기 하층에 Rh 성분 또는 Pd-Rh 합금이 포함되는 3 내지 40um 두께의 박층의 상층을 도포하는 단계를 포함한다. 또한, 상기 (i) 및 (ii) 단계가 결합되는, 구체적으로는, 본원에서 참고문헌으로 통합되는 2015년12월2일자 출원된 대한민국 특허출원 제10-2015-0170368 (명칭: Ｐｄ-Ｒｈ 합금을 포함하는 삼원촉매)에 상세히 기재된 소위 원-포트 반응에 의한 Pd-Rh 합금을 포함하는 슬러리 워시코트가 제조될 수 있다. 개략적으로는 귀금속과 지지체, 산소저장물질, 첨가제를 혼합하여 슬러리 워시코트를 제조하는 단계가 상기 (i) 및 (ii) 단계를 대체할 수 있다. 비제한적으로 상기 하층 및 상층의 Rh 성분의 중량비는 5:95 내지 95:5인 것을 특징으로 하고, 박층의 최적 코팅량은 10 내지 70g/L인 것을 특징으로 한다. 본 발명에 의한 삼원촉매 제조방법의 하층 제조 단계는 Pd 및 Rh 성분들이 합금을 형성하지 않는 경우 및 최근 본 출원인에 의해 성능 향상이 확인된 Pd 및 Rh 성분들이 합금을 형성하는 경우 모두의 하층 구성 제조 단계를 포함한다. 상기 방법에 의해 제조된 촉매 본체는 자동차 배기가스 정화용 삼원촉매로 적용된다. 박층 (상층)에 도포되는 Rh 성분은 촉매 본체에 적용되는 총 로듐 성분의 5~95% 중량이 적용된다. 5 중량%는 본 발명에 의한 삼원촉매에서 박층으로 light off를 개선시키는 최소량이고, 95 중량%는, 하층에 최소한 존재하여야 할 로듐 함량이 5 중량%라는 점을 고려한 것이다. 박층에는 로듐만이 아니라, 팔라듐-로듐 합금이 박층 주성분으로 존재할 수도 있고, 이때 적용되는 로듐 함량 및/또는 팔라듐 함량은 역시 상기된 바와 동일하게 적용될 수 있다는 것은 당업자가 예상할 수 있는 범위이다. 박층의 귀금속 성분은 로듐 또는 팔라듐-로듐 합금이고, 기타 구성성분으로는 상기 귀금속 성분들을 담지하는 무기산화물, 예컨대 알루미나, 산소저장물질 등 당업계에서 이해할 수 있는 구성요소들을 가질 수 있다.The present invention relates to a process for producing a catalyst body comprising a noble metal component-containing thin layer, comprising the steps of: (i) producing a Pt / Pd impregnated support and a Rh impregnated support; (ii) mixing the impregnated supports with the additive, ; (iii) coating the slurry wash coat on a substrate to produce a lower layer; And (iv) applying an upper layer of a thin layer having a thickness of 3 to 40 袖 m in which the lower layer contains a Rh component or a Pd-Rh alloy. In addition, Korean Patent Application No. 10-2015-0170368 filed on December 2, 2015, which is incorporated herein by reference, which is a combination of the above-mentioned steps (i) and (ii) Lt; RTI ID = 0.0 > Pd-Rh < / RTI > alloy by so-called one-port reaction described in detail in US Pat. Generally, the step of mixing a precious metal and a support, an oxygen storage material, and an additive to prepare a slurry wash coat may replace steps (i) and (ii) above. The weight ratio of the Rh component in the lower layer and the upper layer is 5:95 to 95: 5, and the optimal coating amount of the thin layer is 10 to 70 g / L. The lower layer preparation step of the three-way catalyst preparation method according to the present invention is a step in which the Pd and Rh components do not form an alloy, and in the case where the Pd and Rh components confirmed to have improved performance by the present applicant recently form an alloy, . The catalyst body prepared by the above method is applied as a three-way catalyst for automobile exhaust gas purification. The Rh component applied to the thin layer (upper layer) is applied in a weight of 5 to 95% of the total rhodium component applied to the catalyst body. 5% by weight is the minimum amount to improve the light off by thinning in the three-way catalyst according to the present invention, and 95% by weight, considering that the rhodium content to be present in the lower layer should be at least 5% by weight. It is a range that a person skilled in the art can expect that the thin layer may be a thin layer main component, not only rhodium, but also a rhodium content and / or a palladium content may be applied as described above. The noble metal component of the thin layer is rhodium or palladium-rhodium alloy, and other constituent components may have components which are understood in the art such as inorganic oxides carrying the noble metal components, such as alumina, oxygen storage material.
본 발명에 의한 촉매는 박층 부재 촉매와 비교하여 THC, CO 및 NOx 배출에 있어서 향상된 결과를 주며, 따라서 동량의 귀금속을 사용하되, 귀금속의 일부를 박층으로 도포한다면 삼원촉매의 성능은 크게 향상된다.The catalyst according to the present invention gives improved results in THC, CO and NOx emissions as compared with the thin layer member catalyst, and therefore the performance of the three-way catalyst is greatly improved if the same amount of noble metal is used but a part of the noble metal is applied as a thin layer.
도 1 (a)는 종래 단일층 삼원촉매의 개념도를 도시한 것이고, (b)는 귀금속 성분으로서 Rh이 박층에 포함되는 본 발명의 삼원촉매 개념도를 도시한 것이다.
도 2는 도 1(a)의 종래 단일층 삼원촉매 성능 시험 결과 및 도 1(b)의 Rh 박층이 형성되는 본 발명의 삼원촉매 성능 시험 결과를 비교한 것이다.
도 3은 비교예 및 실시예들의 박층 두께 차이를 보이는 주사전자현미경 사진들이다.
도 4는 Rh 박층 최적화를 보이는 light off 측정 그래프이다.FIG. 1 (a) is a conceptual diagram of a conventional single-layer three-way catalyst, and FIG. 1 (b) shows a three-way catalyst conceptual diagram of the present invention in which Rh is contained as a noble metal component in a thin layer.
2 compares the results of the conventional single-layer three-way catalyst performance test of FIG. 1 (a) and the three-way catalyst performance test of the present invention in which the Rh thin layer of FIG. 1 (b) is formed.
FIG. 3 is a scanning electron microscope photograph showing the thin layer thickness difference of Comparative Examples and Examples.
4 is a light off measurement graph showing Rh thin layer optimization.
정의Justice
본원에서 사용되는 용어 '촉매'란 지지체 예컨대 알루미나 분말에 활성성분 예컨대 Pd, Rh이 담지된 분말 형태를 의미하고, '촉매 본체'란 상기 '촉매'가 기재 예컨대 코디어라이트에 도포된 구조체를 의미한다. '워시코트'란 상기 촉매와 기타 성분들이 혼합된 슬러리를 의미한다. 워시코트가 기재에 도포되어 촉매 본체를 형성한다. 그러나 당업자가 이해하듯이 촉매 또는 촉매 본체라는 용어는 상호 교환적으로 사용될 수 있다. '열처리 단계'라 함은, 전구체 상태에 있는 원료 성분들을 안정 구조로 유도하기 위한 가열 단계로서 특히 배기가스 분위기에서의 가열 단계를 의미한다. '배기가스 분위기'라 함은, 가솔린 엔진에서 방출되는 배기가스 성분들 예컨대 O2, CO2, CO, H2, HC (AHC (방향족 탄화수소), 프로판/프로펜 등), NOx, H2O를 포함하는 것으로, 당업계에서는 5 내지 10 중량%의 H2O를 포함하고 O2, CO2, CO, H2, HC (AHC (방향족 탄화수소), 프로판/프로펜 등), NOx, N2 성분들은 0 내지 15 중량%까지 변하는 분위기를 의미한다. 본원에서 '예비 촉매'라 함은 열처리 단계가 적용되기 전 구조적으로는 합금화가 진행되지 않은 상태의 촉매를 의미하고, 구체적으로는 지지체에 전구체들이 단순히 담지된 상태의 촉매를 의미한다. 본원에서 로듐 또는 팔라듐-로듐 합금의 박층이라 함은, 상층을 이루는 박층에 로듐 또는 팔라듐-로듐 합금으로 이루어지는 것이 아니라, 무기산화물, 예컨대 알루미나, 산소저장물질 등 당업계에서 이해할 수 있는 구성요소들이 포함되는 것이나, 편의상 로듐 또는 팔라듐-로듐 합금의 박층이라 칭한다.The term 'catalyst' as used herein means a powder form in which an active component such as Pd and Rh is supported on a support such as alumina powder, and the term 'catalyst body' means a structure coated on a substrate such as cordierite do. &Quot; Wash coat " means a slurry in which the catalyst and other components are mixed. A washcoat is applied to the substrate to form the catalyst body. However, as will be appreciated by those skilled in the art, the term catalyst or catalyst body may be used interchangeably. The term 'heat treatment step' refers to a heating step for guiding raw materials in a precursor state to a stable structure, and in particular, a heating step in an exhaust gas atmosphere. "Exhaust gas atmosphere" shall mean, in the exhaust gas components emitted from a gasoline engine for example, O 2, CO 2, CO, H 2, HC (AHC ( aromatic hydrocarbon), propane / propene, etc.), NOx, H 2 O in that, the art, including the including H 2 O of from 5 to 10% by weight of O 2, CO 2, CO, H 2, HC (AHC ( aromatic hydrocarbon), propane / propene, etc.), NOx, N 2 The components mean an atmosphere varying from 0 to 15% by weight. As used herein, the term 'preliminary catalyst' refers to a catalyst in a state in which the alloying is not proceeded before the heat treatment step is applied, and specifically refers to a catalyst in which precursors are simply supported on a support. Herein, the thin layer of rhodium or palladium-rhodium alloy means that the thin layer constituting the upper layer is not composed of rhodium or palladium-rhodium alloy but includes inorganic oxide such as alumina and oxygen storage material, For convenience, it is referred to as a thin layer of rhodium or palladium-rhodium alloy.
삼원촉매 귀금속 성분들 중 팔라듐 및 로듐 배치와 관련하여 당업계에서 실무적으로 인정되는 구성에서 팔라듐 및 로듐은 개별 성분으로 존재한다. 즉, 이들 팔라듐 및 로듐은 서로 접근하거나 인접하지 않도록 촉매를 구성한다. 예를들면 지지체에 팔라듐을 담지한 후 열적으로 고정시킴과 동시에 또 다른 지지체에 로듐을 담지한 후 열적으로 고정시킨 후, 이들을 워시코트로 제작하여 코디어라이트에 도포함으로써 삼원촉매 본체를 제조하고, 본체는 canning 작업을 통해 자동차 배기시스템에 장착된다. 이와는 달리, 새로운 팔라듐 및 로듐 배치 개념은 팔라듐 및 로듐의 합금화를 통한 삼원촉매 성능 개선 방법이다. Palladium and rhodium are present as discrete components in configurations that are practically recognized in the art in connection with palladium and rhodium placement among the three-way catalytic noble metal components. That is, these palladium and rhodium constitute the catalyst so that they do not approach each other or adjoin each other. For example, palladium is supported on a support and then thermally fixed, and further rhodium is supported on another support and then thermally fixed. Then, the support is coated with cordierite to prepare a three-way catalyst body, The body is mounted to the vehicle exhaust system via a canning operation. In contrast, the new concept of palladium and rhodium placement is a way to improve three-way catalytic performance through the alloying of palladium and rhodium.
본 발명에서 도입되는 귀금속 박층 개념은 상기 종래 삼원촉매 구성 및 Pd-Rh 합금화를 통한 새로운 삼원촉매 구성에 적용될 수 있고, 즉 귀금속 성분 박층 아래에 배치되는 하층의 구성과는 무관하게, 종래 하층에서 적용되는 로듐 또는 팔라듐-로듐 성분 중 일부, 바람직하게는 촉매에 적용되는 총 Rh 성분 (및 Pd 성분)의 5 내지 95 중량%가 상층에 박층, 예컨대 5 내지 40um로 적층되면 삼원촉매 성능이 개선된다는 것을 확인한 것이다.The concept of a noble metal thin layer introduced in the present invention can be applied to a novel three-way catalyst constitution by the above-mentioned conventional three-way catalyst composition and Pd-Rh alloying, that is, regardless of the constitution of a lower layer disposed below a noble metal component thin layer, (And the Pd component) applied to the catalyst is laminated on the upper layer to a thin layer, for example, 5 to 40 um, to improve the three-way catalyst performance It is confirmed.
본 발명에 대한 이론적 근거는, NO 경우 HC, CO와 경쟁 흡착하고, 활성점에 NO가 흡착하게 됨에 따라 HC, CO 흡착/반응성이 낮아진다는 측면 및 자동차 배기가스 정화용 촉매에서 활성물질로 사용되는 귀금속 중 Rh이 질소산화물(NOx) 환원에 우수하므로 NOx에 대한 제거를 우선적으로 진행하여 HC, CO에 대한 흡착점을 유지, 반응성 개선한다는 측면이다.The rationale for the present invention is that the NO adsorption / reactivity is lowered as NO is adsorbed competing with HC and CO in the NO state and NO is adsorbed to the active site, and that the adsorption / (Rh) is superior to nitrogen oxides (NOx) reduction, so that the removal of NOx is preferentially proceeded to maintain the adsorption point for HC and CO, and the reactivity is improved.
이하 본 발명을 실시예들을 통하여 상세히 설명하지만 본 발명의 사상이 이에 국한되지 않는다는 것은 분명하다. 예를들면 본 발명에 의한 삼원촉매에 있어서 하층의 귀금속 성분으로서 Pt 성분이 포함될 수 있으나, 본원에 있어서 상층의 박막 특성을 단순하고도 간결하게 설명하기 위하여, Pd 및 Rh 성분만을 기재하고, 또한 하층에서 Pd 및 Rh 성분은 비-합금 또는 합금 형태로 구성될 수 있으나, 하기 실시예들에서는 합금 형태의 Pd-Rh 구성을 언급한다. 또한 Rh (또는 Pd-Rh) 성분이 얇게 코팅되는 상층에는 당업계에서 통상적으로 적용되는 성분들 예컨대, 산소저장물질, 기타 조촉매 성분들이 포함될 수 있으나, 이는 통상의 기술 범위이므로 상세한 설명이 생략된다.Hereinafter, the present invention will be described in detail with reference to Examples, but it should be understood that the present invention is not limited thereto. For example, in the three-way catalyst according to the present invention, a Pt component may be included as a noble metal component in the lower layer. However, in order to simply and concisely explain the characteristics of the upper layer in the present invention, only Pd and Rh components are described, , The Pd and Rh components may be in the form of a non-alloy or alloy, but the following embodiments refer to a Pd-Rh composition in the form of an alloy. The upper layer on which the Rh (or Pd-Rh) component is thinly coated may include components commonly used in the art, such as oxygen storage materials and other cocatalyst components. .
비교예Comparative Example
PdN (Pd-질산염) 및 RhN (Rh-질산염) 수용액을 순차적으로 또는 동시에 지지체 Al2O3 분말에 Pd-Rh 중량비가 9:1이 되도록 함침하였다. 상기 알루미나 분말을 오븐에서 150℃에서 5시간 건조시키고, 400℃ 내지 650℃에서 5 시간 소성하여 예비 촉매를 제조하였다. 얻어진 예비 촉매를 이용하여 슬러리를 제조하고 통상의 방법으로 기재에 코팅한 후 환원가스 분위기 예컨대 배기가스 분위기에서 500 내지 1100℃에서 1 내지 50 시간, 바람직하게는 12시간으로 열처리하여 촉매 비교 본체를 제조하였다.An aqueous solution of PdN (Pd-nitrate) and RhN (Rh-nitrate) was impregnated sequentially or simultaneously to the support Al 2 O 3 powder such that the weight ratio of Pd-Rh was 9: 1. The alumina powder was dried in an oven at 150 DEG C for 5 hours and calcined at 400 DEG C to 650 DEG C for 5 hours to prepare a pre-catalyst. The obtained preliminary catalyst is used to prepare a slurry, which is then coated on a substrate by a conventional method and then heat-treated in a reducing gas atmosphere such as an exhaust gas atmosphere at 500 to 1100 ° C for 1 to 50 hours, preferably 12 hours, Respectively.
실시예 1Example 1
Rh 수용액을 알루미나에 함침하고 용매에 분산한 후 밀링하여 별도로 제조된 Rh 코팅액을 상기 비교예에 의해 제조된 촉매 비교 본체에 박층으로서 코팅하고, 건조, 소성하여 촉매 본체를 완성하였다. 이때 박층에 사용된 Rh량은 촉매 본체에 사용되는 로듐 총량의 50 중량%에 해당된다. 상세하게는, 비교예에서 사용되는 (하층의) 로듐 성분을 1/2로 적용하고 박층인 상층에 나머지 1/2을 적용하여, 비교예의 촉매 본체에서 사용되는 로듐 함량과 동일 함량이 적용되었다 (상층의 로듐 코팅 두께 5-10 um, 코팅량 10 g/L).The Rh aqueous solution was impregnated with alumina, dispersed in a solvent, and then milled. The separately prepared Rh coating solution was coated as a thin layer on the catalyst comparison body prepared in the above Comparative Example, followed by drying and firing to complete the catalyst body. The amount of Rh used in the thin layer corresponds to 50% by weight of the total amount of rhodium used in the catalyst body. Specifically, the same rhodium content as that used in the catalyst body of the comparative example was applied, applying the rhodium component (of the lower layer) used in the comparative example to 1/2 and applying the remaining 1/2 to the upper layer of the thin layer Rhodium coating thickness of the upper layer 5-10 um, coating amount 10 g / L).
실시예 2Example 2
실시예 1과 동일하게 제조하되, 코팅량 30 g/L로 도포하여 로듐 코팅 두께 13-18 um를 얻었다.Was prepared in the same manner as in Example 1, and coated with a coating amount of 30 g / L to obtain a rhodium coating thickness of 13 to 18 μm.
실시예 3Example 3
실시예 1과 동일하게 제조하되, 코팅량 50 g/L로 도포하여 로듐 코팅 두께 23-28 um를 얻었다.Was prepared in the same manner as in Example 1 except that a coating amount of 50 g / L was applied to obtain a rhodium coating thickness of 23-28 μm.
실시예 4Example 4
실시예 1과 동일하게 제조하되, 코팅량 70 g/L로 도포하여 로듐 코팅 두께 35-40 um를 얻었다.A coating amount of 70 g / L was coated in the same manner as in Example 1 to obtain a rhodium coating thickness of 35-40 μm.
상기 비교예 및 실시예들의 박층 (상승) 구성은 다음과 같이 요약된다.The thin (rising) configuration of the above comparative examples and embodiments is summarized as follows.
주사전자현미경으로 400배율로 관찰된 사진들을 도 3에 제시한다.Photographs observed with a scanning electron microscope at 400 magnification are shown in FIG.
실시예들에서 제조된 촉매 본체를 대상으로 light off을 측정한 결과를 도 3에 제시한다. HC, CO 및 NOx 모두에 대하여 (박층이 부재한) 비교예보다 우수한 결과를 주었다. 또한 놀랍게도 상층의 두께는 소정의 최적화 범위를 가진다는 것을 확인하였다. 즉 두께 23-28um에서 가장 우수한 활성을 보인다. 도 4는 박층 존재 및 부재의 촉매 본체에 대한 엔진 테스트 결과를 제시한 것이다. 본 발명에 의한 촉매 본체는 비교예 (박층 부재)와 대비하여 THC, CO 및 NOx 배출에 있어서 향상된 결과를 주었다. 따라서, 동량의 귀금속을 사용하되, 귀금속의 일부를 박층으로 배치한다면 삼원촉매의 성능은 크게 향상된다는 것을 확인하였다.The results of light off measurements on the catalyst bodies prepared in the examples are shown in FIG. Gave better results than the comparative example (with no thin layer) for both HC, CO and NOx. Surprisingly, it has been confirmed that the thickness of the upper layer has a predetermined optimization range. In other words, it shows the best activity at a thickness of 23-28 μm. Figure 4 presents engine test results for a catalyst body of a thin layer presence and absence. The catalyst bodies according to the invention gave improved results in THC, CO and NOx emissions as compared to the comparative examples (thin layer members). Therefore, it was confirmed that the performance of the three-way catalyst was greatly improved by using the same amount of noble metal but arranging a part of the noble metal as a thin layer.
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| JP2002346391A (en) | 2001-05-25 | 2002-12-03 | Suzuki Motor Corp | Exhaust gas cleaning catalyst and method for manufacturing the same |
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| JP5737699B2 (en) | 2012-09-18 | 2015-06-17 | 国立研究開発法人科学技術振興機構 | Catalyst using PdRu solid solution type alloy fine particles |
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| JP2002346391A (en) | 2001-05-25 | 2002-12-03 | Suzuki Motor Corp | Exhaust gas cleaning catalyst and method for manufacturing the same |
| JP5737699B2 (en) | 2012-09-18 | 2015-06-17 | 国立研究開発法人科学技術振興機構 | Catalyst using PdRu solid solution type alloy fine particles |
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