An effective strategy to enhance the sulfur resistance of Ce-based catalyst for low temperature SCR reaction

Abstract

SO2 has a significant impact on SCR reaction, and how to suppress the effect of SO2 on Ce-based catalyst activity has been a goal pursued by the scientific community. In this work, the CeSmFTi catalyst was prepared by one-pot hydrothermal method to study the catalytic activity and SO2 resistance performance in NH3-SCR reaction. The experimental findings suggested that Ce5Sm1FTi94 catalyst had better catalytic performance, with the NO conversion exceeding 90% at 320 °C. After enduring SO2 test, the NO conversion could gradually recover to more than 80%. The results showed that the presence of CeF3 efficiently regulated the proportion of active state Ce3+ and accelerated the “fast SCR” reaction, which significantly enhanced the catalytic performance of the catalyst and inhibited the oxidation of SO2. Notably, doping a certain amount of Sm into Ce5FTi94 catalyst not only improved the surface acidity and redox performance, but also promoted the electron transfer and interaction between Ce and Sm species, thereby inhibiting the combination of SO2 and cerium species. Therefore, the formation of sulfate species on the catalyst was minimized, resulting in a better SO2 tolerance. Simultaneously, the in-situ DRIFTs analysis revealed that both L-H and E-R mechanisms were presented on Ce5Sm1FTi94 catalyst to carry out the NH3-SCR reaction process, with the L-H mechanism being dominant.