Effect of Ce doping into V₂O₅-WO₃/TiO₂ catalysts on the selective catalytic reduction of NO_x by NH₃

Mengyin Chen¹，Mengmeng Zhao¹，Fushun Tang¹，Le Ruan¹，Ning Li¹

1. College of Chemistry and Bioengineering, Guilin University of Technology, Collaborative Innovation Center for Exploration of Hidden Nonferrous Metal Deposits, Development of New Materials in Guangxi

摘 要：In this work, the effectiveness of V₂O₅-WO₃/TiO₂ catalysts modified with different CeO₂ contents by impregnation and co-precipitation methods on the selective catalytic reduction of NOxby NH3 have been studied comparatively by various experimental techniques. The results showed that the NO conversion of V₂O₅-WO₃/CeO₂-TiO₂ catalysts modified by co-precipitation method obviously increased with the Ce doping contents in the studied range below 20%（All Ce contents are in mass fractions）, but the NO conversion of V₂O₅-WO₃/CeO₂/TiO₂ catalysts modified by impregnation methods was lower than V₂O₅-WO₃/CeO₂-TiO₂ catalysts especially beyond 2.5% Ce doping contents. The V₂O₅-WO₃/CeO₂-TiO₂ catalysts showed better SCR activity, wider reaction window, and higher sulfur and water resistance. The characterization results elucidated that the modified catalysts by co-precipitation method exhibited higher specific surface area, much better dispersity of Ce component, more Ce³⁺species and more Br?nsted acid sites than that by impregnation. The vacancies caused by more Ce³⁺species were favorable for more NO oxidation to NO₂, and the interaction between Ce species and WOxspecies generated more Br?nsted acid sites. It could be supposed that dispersed Ce Oxspecies and WOxspecies offered more second active centers respectively to adsorb oxygen and activate ammonia as co-catalysis to the primary active center of V ions, thus facilitated the better SCR activity of modified V₂O₅-WO₃/CeO₂-TiO₂ catalysts by coprecipitation methods. The co-precipitation methods with Ce component were more suitable for production of modified commercial V₂O₅-WO₃/TiO₂ catalysts.

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