Influence of preparation methods of supports on the deNO performance and alkali-metal resistance over TiO2/CeO2 catalysts in NH3-SCR reaction

Two kinds of CeO2 supports were synthesized by precipitation method and hydrothermal method, respectively, and then TiO2 species were loaded on their surface to prepare two TiO2/CeO2 catalysts (abbreviated as Ti/Ce-PM and Ti/Ce-HM). Experimental results show that Ti/Ce-PM and Ti/Ce-HM catalysts exhibit irregular nanoparticle morphology and specific tubular morphology, respectively, while the deNOx performance and anti-K poisoning ability of Ti/Ce-HM catalyst are worse than those of Ti/Ce-PM catalyst, which suggests that the random loading of TiO2 species on the tubular CeO2 support doesn’t enhance the deNOx performance and alkali-metal resistance. However, physicochemical property characterizations display that the excellent deNOx performance of Ti/Ce-PM catalyst can be attributed to better dispersion of TiO2 species, more excellent redox performance and surface acidity (especially B acid), larger Ce3+ content and Oα ratio, stronger electron interaction between Ce and Ti through the redox cycle of Ce3+ + Ti4+ ↔ Ce4+ + Ti3+, as well as easier desorption and decomposition of the adsorbed NOx species. Furthermore, stronger anti-K poisoning ability of Ti/Ce-PM catalyst results from that the negative impact of K2O species on the redox performance, surface acidity, Ce3+ content, and Oα ratio of Ti/Ce-PM catalyst is smaller than that on Ti/Ce-HM catalyst.