Influence of preparation methods of supports on the deNOx performance and alkali-metal resistance over TiO2/CeO2 catalysts in NH3-SCR reaction. (15th July 2022) - Yao, Xiaojiang
Graphical abstract: Highlights: Two kinds of particulate and tubular CeO2 supports (Ce-PM and Ce-HM) are prepared. Redox performance and surface acidity of Ti/Ce-PM catalyst are better than Ti/Ce-HM catalyst. Ce 3+ content and Oα ratio of Ti/Ce-PM catalyst are larger than Ti/Ce-HM catalyst. Ti/Ce-PM catalyst exhibits better de NO x performance and anti-K poisoning ability. NH3 -SCR reaction mainly follows an L-H mechanism on these TiO2 /CeO2 catalysts. Abstract: 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 de NO x 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 de NO x performance and alkali-metal resistance. However, physicochemical property characterizations display that the excellent de NO x 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 Ce 3+ content and Oα ratio, stronger electron interaction between Ce and Ti through the redox cycle of Ce 3+ + Ti 4+ ↔ Ce 4+ + Ti 3+, as well as easier desorption and decomposition of the adsorbed NO x species. Furthermore, stronger anti-K poisoning ability of Ti/Ce-PM catalyst results from that the negative impact of K2 O species on the redox performance, surface acidity, Ce 3+ content, and Oα ratio of Ti/Ce-PM catalyst is smaller than that on Ti/Ce-HM catalyst.