Impact of high-temperature desulfation on the performance of Pd-based TWC
1
조회
0
다운로드
1
인용
0
참고문헌
키워드
초록
Regulations on environmental pollution caused by automobile exhaust gases are becoming increasingly stringent worldwide. Additionally, according to the most recent United States Environmental Protection Agency standard, Tier 3 regulations, the durability requirements for after-treatment have increased from 120,000 to 150,000 miles. The main causes of shortening the life of the catalyst are the sintering of precious metals by high temperature and poisoning by the strong adsorption of impurities. In particular, sulfur, phosphorus, and zinc contained in lubricant additives are the main causes of catalyst life reduction. It is known that the degradation of catalyst performance due to sulfur poisoning is reversible through a high-temperature desulfation process. However, the catalysts ex-posed to a high temperature in this process, especially three-way catalysts (TWCs) containing oxygen storage capacity (OSC) materials, adversely affect the catalyst performance due to CeO2 agglomeration and sintering of precious metal particles. Therefore, the purpose of this study was to investigate the effect of the high-temperature desulfation process on the performance of Pd-based TWCs. A gasoline engine bench called Genset was used to perform accelerated thermal aging and lubricant additive poisoning of the TWCs for 24 h at a catalyst temperature of 700°C. Once the accelerated thermal aging and poisoning TWC samples were obtained, the desulfation process at high temperature and evaluations of TWC performance (temperature sweep and OSC) were carried out in a bench flow reactor using simulated engine exhaust gases. For the accelerated thermal aging TWC sample, the conversion of NO, CO, C3H6, and C3H8 after desulfation was similar to that before desulfation, but the OSC decreased by up to 22%. However, the accelerated poisoning TWC sample was found to have improved the conversion of NO, CO, C3H6, and C3H8 and the performance of OSC after desulfation.
Abstract
Regulations on environmental pollution caused by automobile exhaust gases are becoming increasingly stringent worldwide. Additionally, according to the most recent United States Environmental Protection Agency standard, Tier 3 regulations, the durability requirements for after-treatment have increased from 120,000 to 150,000 miles. The main causes of shortening the life of the catalyst are the sintering of precious metals by high temperature and poisoning by the strong adsorption of impurities. In particular, sulfur, phosphorus, and zinc contained in lubricant additives are the main causes of catalyst life reduction. It is known that the degradation of catalyst performance due to sulfur poisoning is reversible through a high-temperature desulfation process. However, the catalysts ex-posed to a high temperature in this process, especially three-way catalysts (TWCs) containing oxygen storage capacity (OSC) materials, adversely affect the catalyst performance due to CeO2 agglomeration and sintering of precious metal particles. Therefore, the purpose of this study was to investigate the effect of the high-temperature desulfation process on the performance of Pd-based TWCs. A gasoline engine bench called Genset was used to perform accelerated thermal aging and lubricant additive poisoning of the TWCs for 24 h at a catalyst temperature of 700°C. Once the accelerated thermal aging and poisoning TWC samples were obtained, the desulfation process at high temperature and evaluations of TWC performance (temperature sweep and OSC) were carried out in a bench flow reactor using simulated engine exhaust gases. For the accelerated thermal aging TWC sample, the conversion of NO, CO, C3H6, and C3H8 after desulfation was similar to that before desulfation, but the OSC decreased by up to 22%. However, the accelerated poisoning TWC sample was found to have improved the conversion of NO, CO, C3H6, and C3H8 and the performance of OSC after desulfation.
참고문헌 (19)
- M. V. Twigg, "Progress and future challenges in controlling automotive exhaust gas emissions", Applied Catalysis B:Environmental, 70(1-4), pp.2~15 (2007)
- J. Kašpar, "Use of CeO2-based oxides in the three-way catalysis", Catalysis Today, 50(2), pp.285~298 (1999)
- P. Granger, "Investigation of the intrinsic activity of ZrxCe1-xO2 mixed oxides in the CO+ NO reactions : Influence of Pd incorporation", Topics in Catalysis, 16, pp.89~94 (2001)
- R. M. Heck, "Catalytic air pollution control : Commercial technology", Platinum Metals Review, 54(3), pp.180~183 (2010)
- Y. Y. Yao, "The oxidation of CO and hydrocarbons over noble metal catalysts", Journal of Catalysis, 87(1), pp.152~162 (1984)
- C. F. Cullis, "Oxidation of methane over supported precious metal catalysts", Journal of Catalysis, 83(2), pp.267~285 (1983)
- H. S. Gandhi, "Effects of sulphur on noble metal automotive catalysts", Applied Catalysis, 77(2), pp.175~186 (1991)
- H. S. Gandhi, "Affinity of lead for noble metals on different supports", Surface and Interface Analysis, 6(4), pp.149~161 (1984)
- W. B. Chamberlin, "Balancing crankcase lubricant performance with catalyst life", SAE Transactions, pp.841407~ (1984)
- M. J. Rokosz, "Characterization of phosphoruspoisoned automotive exhaust catalysts", Applied Catalysis B : Environmental, 33(3), pp.205~215 (2001)
- L. Xu, "Cerium phosphate in automotive exhaust catalyst poisoning", Applied Catalysis B : Environmental, 50(2), pp.113~125 (2004)
- C. Larese, "Deactivation of real three way catalysts by CePO4 formation", Applied Catalysis B : Environmental, 40(4), pp.305~317 (2003)
- M. L. Granados, "Effect of mileage on the deactivation of vehicle-aged three-way catalysts", Catalysis Today, 107-108, pp.77~85 (2005)
- 남정길, "Cu-Chabazite SCR Catalysts의 황 피독 및 탈황에 의한 NOx 저감성능에 관한 연구", 한국마린엔지니어링학회지, 37(8), pp.855~861 (2013), 한국마린엔지니어링학회[DOI]
- D. W. Brookshear, "Impact of sulfation and desulfation on NOx reduction using Cu-chabazite SCR catalysts", Catalysis Today, 258(Part 2), pp.359~366 (2015)
- Lubricating Oil Consumption on the Standard Road Cycle, "B. West", SAE, ~, pp.Technical Paper No. 2013-01-0884 (2013)
- C. Larese, "Effects of the CePO4 on the oxygen storage and release properties of CeO2 and Ce0. 8Zr0. 2O2 solid solution", Journal of Catalysis, 226(2), pp.443~456 (2004)
- C. Xie, "Impact of lubricant additives on the physicochemical properties and activity of three-way catalysts", Catalysts, 6(4), pp.54~ (2016)
- D. Kim, "Impact of lubricant oil additives on the performance of Pd-based three-way catalysts", Emission Control Science and Technology, 6, pp.139~150 (2020)