摘要
采用共沉淀法制备了不同铈锆比的粉末铈锆固溶体,考察了铈锆比和铈锆固溶体负载量对浸渍法制备的颗粒状和整体样贵金属催化剂上C3H6(丙烯)氧化反应催化性能的影响,并运用XRD和TPD表征技术对催化剂的物化性能进行研究。结果表明,所制备的催化剂中均形成了铈锆固溶体,并且铈锆含量的增加能够提高催化剂对C3H6的吸附能力。当铈锆固溶体的负载量相同时,在氧化气氛和较低贵金属含量条件下、Ce0.6Zr0.4O2的加入使催化剂在低温时具有最好的催化效果。但与Pt/Al2O3相比,采用浸渍法添加铈锆固溶体降低了贵金属整体样催化剂的活性,且活性随着负载量的增加显著降低。
CexZr1-xO2 solid solution was prepared by co-precipitation method, while powder and monolith honeycomb catalysts were prepared by impregnating carriers with certain CexZr1-xO2 aqueous solution. The crystalline structures of CexZr1-xO2 and Ce0.5Zr0.5O2/Al2O3 were characterized by XRD, and the adsorbability was examined by TPD-C3H6. The results showed that the solid solution was obtained in CeO2-ZrO2 composite oxides, the addition of CeO2-ZrO2 to γ-Al2O3 improved the adsorptive power of CexZr1-xO2/Al2O3 to C3H6. The behavior of these catalysts was examined by propene oxidation in a fixed-bed microreactor under excess oxygen. It was found that when the adding amount of CexZr1-xO2 was equal, Pt/Ce0.6Zr0.4O2/Al2O3/cordierite showed the best activity, which was still lower than that of Pt/Al2O3/cordierite. So the addition of ceria-zirconia solid solution restrained the catalytic activity in the presence of excessive oxygen, when the amount of noble metal such as platinum was quite low. The more the ceria-zirconia solid solution was loaded, the worse was the performance of the catalysts as oxidative catalyst.
出处
《贵金属》
CAS
CSCD
2006年第2期39-44,共6页
Precious Metals
基金
国家自然科学基金重点项目(20437010)
国家863课题(2003AA643020)
关键词
环境工程
汽车尾气
共沉淀法
氧化铈-氧化锆
固溶体
贵金属催化剂
氧化
Environment engineering
Automotive emission
Co-precipitation
Ceria-zirconia
Solid solution
Noble metal catalyst
Oxidation
