Soot combustion performance and H2-TPR study on ceria-based mixed oxides

Abstract

Ceria (CeO 2 ) catalysts doped with different metal ions were prepared by sol-gel or impregnation methods, and their catalytic activity for soot combustion was evaluated by thermogravimetry. Temperature-programmed reduction was used to investigate the influence of their redox properties on soot combustion performance. The results indicate that the oxidation temperature of soot can be significantly reduced using catalysts containing transition metals, which provide increased surface and lattice oxygen compared with undoped CeO 2 . The ability of each catalyst to deliver active oxygen at low temperature (200–400 °C) plays an important role in determining catalytic performance. However, incorporation of structure promoter, alkali metals, and alkaline earth metals increase the delivery of active oxygen only at moderate temperature (above 400 °C), which accelerate the combustion rate of soot. 采用溶胶-凝胶法或浸渍法制备了不同金属离子掺杂的铈基复合氧化物催化剂, 并采用热重法考察其催化碳烟燃烧的活性, 借助H 2 -TPR (程序升温还原)手段探讨了催化剂氧化还原性对碳烟燃烧性能的影响. 结果表明, 过渡金属的掺杂促使催化剂在低温下提供更多的表面氧和晶格氧, 显著降低了碳烟的氧化温度, 催化剂于200~400 °C释放的活性氧数量对于碳烟燃烧性能提高至关重要; 而结构性助剂金属、碱金属或碱土金属的掺入可提高中温活性氧数量, 虽然对碳烟起燃温度无明显改善, 但加快了碳烟的燃烧速率. The influence of doping ceria with different kinds of metal ions on its redox properties for soot combustion was investigated. The oxidation temperature of soot could be significantly reduced using ceria doped with transition metals because more active oxygen was generated at low temperature. In contrast, doping ceria with alkali metal and alkaline earth metals increased the combustion rate of soot.