Sn.sup.2+ Regulated Thermal Stability of the Cerium Oxide Lattice During Soot Combustion

In this paper, Ce.sub.xSn.sub.1-xO.sub.y-F (x = 1, 0.75, 0.5, 0.25, 0) and Ce.sub.xSn.sub.1-xO.sub.y-A were prepared through a typical reverse co-precipitation method. The experimental results showed that Sn doping could improve the activity and thermal stability of CeO.sub.2 in different modes. Comparing the activity and characterization of Ce.sub.xSn.sub.1-xO.sub.y-F and Ce.sub.xSn.sub.1-xO.sub.y-A, the improvement of catalyst activity was attributed to the Ce-O-Sn structure with more oxygen vacancies formed by Sn doping, whereas the enhancement of thermal stability was related to the Sn.sup.2+ remaining in the CeO.sub.2 lattice after accelerated aging. Therefore, a mechanism was proposed that Ce.sup.4+-O-Sn.sup.2+ is more stable than Ce.sup.4+-O-Sn.sup.4+ in Ce.sub.xSn.sub.1-xO.sub.y solid solution.