CeO_2-ZrO_2-La_2O_3-Al_2O_3 composite oxide and its supported palladium catalyst for the treatment of exhaust of natural gas engined vehicles  

作　　者：Xiaoyu Zhang Enyan,Long Yile Li Jiaxiu Guo Lijuan Zhang Maochu Gong Minghua Wang Yaoqiang Chen 

机构地区：[1]Key Laboratory of Green Chemistry ＆ Technology of the Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan, China [2]College of Architecture and Environment, Sichuan University, Chengdu 610064, Sichuan, China [3]State Key Laboratory of Catalysis,Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China [4]Sichuan Tianyi Science ＆ Technology Co., Ltd., Chengdu 610225, Sichuan, China

出　　处：《Journal of Natural Gas Chemistry》2009年第2期139-144,共6页天然气化学杂志（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 20773090, 20803049);the National High Technology Researchand Development Program of China (863 Program, No. 2006AA06Z347);the Specialized Research Fund for the Doctoral Program of Higher Education(20070610026)

摘　　要：Composite supports CeO2-ZrO2-Al2O3（CZA） and CeO2-ZrO2-Al2O3-La2O3（CZALa） were prepared by co-precipitation method. Palladium catalysts were prepared by impregnation and their purification ability for CH4, CO and NOx in the mixture gas simulated the exhaust from natural gas vehicles （NGVs） operated under stoichiometric condition was investigated. The effect of La2O3 on the physicochemical properties of supports and catalysts was characterized by various techniques. The characterizations with X-ray diffraction （XRD） and Raman spectroscopy revealed that the doping of La2O3 restrained effectively the sintering of crystallite particles, maintained the crystallite particles in nanoscale and stabilized the crystal phase after calcination at 1000 ℃. The results of N2-adsorption, H2-temperatnre-programmed reduction （H2-TPR） and oxygen storage capacity （OSC） measurements indicated that La2O3 improved the textural properties, reducibility and OSC of composite supports. Activity testing results showed that the catalysts exhibit excellent activities for the simultaneous removal of methane, CO and NOx in the simulated exhaust gas. The catalysts supported on CZALa showed remarkable thermal stability and catalytic activity for the three pollutants, especially for NOx. The prepared palladium catalysts have high ability to remove NOx, CH4 and CO, and they can be used as excellent catalysts for the purification of exhaust from NGVs operated under stoichiometric condition. The catalysts reported in this work also have significant potential in industrial application because of their high performance and low cost.Composite supports CeO2-ZrO2-Al2O3（CZA） and CeO2-ZrO2-Al2O3-La2O3（CZALa） were prepared by co-precipitation method. Palladium catalysts were prepared by impregnation and their purification ability for CH4, CO and NOx in the mixture gas simulated the exhaust from natural gas vehicles （NGVs） operated under stoichiometric condition was investigated. The effect of La2O3 on the physicochemical properties of supports and catalysts was characterized by various techniques. The characterizations with X-ray diffraction （XRD） and Raman spectroscopy revealed that the doping of La2O3 restrained effectively the sintering of crystallite particles, maintained the crystallite particles in nanoscale and stabilized the crystal phase after calcination at 1000 ℃. The results of N2-adsorption, H2-temperatnre-programmed reduction （H2-TPR） and oxygen storage capacity （OSC） measurements indicated that La2O3 improved the textural properties, reducibility and OSC of composite supports. Activity testing results showed that the catalysts exhibit excellent activities for the simultaneous removal of methane, CO and NOx in the simulated exhaust gas. The catalysts supported on CZALa showed remarkable thermal stability and catalytic activity for the three pollutants, especially for NOx. The prepared palladium catalysts have high ability to remove NOx, CH4 and CO, and they can be used as excellent catalysts for the purification of exhaust from NGVs operated under stoichiometric condition. The catalysts reported in this work also have significant potential in industrial application because of their high performance and low cost.

关 键 词：Pd catalysts natural gas vehicles exhaust methane oxidation NOx conversion CeO2-ZrO2-Al2O3 LA2O3 

分 类 号：O643.36[理学—物理化学] U464.174[理学—化学]