Study on CO-SCR performance of Ce modified OMS-2 catalysts

Abstract

The Ce-modified OMS-2 catalyst (Cex-OMS-2) was synthesized by the hydrothermal synthesis method, after which its catalytic efficacy in the selective reduction of NO by CO was assessed. The experiments showed that Ce0.08-OMS-2 was capable of 100% NO conversion between 175 and 300 °C when 0.05%NO, 0.1%CO, 5%O2 and N2 were used as equilibrium gases, and the N2 selectivity peaked at 93.2% at 175 °C. Additionally, Ce0.08-OMS-2 exhibits good sulfur resistance in the presence of 0.02% SO2 and maintains more than 88% NO conversion at 175–275 °C. By using BET, XPS, H2-TPR, NH3-TPD, and In situ DRIFTS to characterize the catalysts, the effects of doping the active metal Ce on the physicochemical characteristics of OMS-2 catalysts were under investigation. In conclusion, the improvement of the low-temperature activity of the Cex-OMS-2 catalyst is facilitated by lower agglomeration and crystallinity, larger specific surface area, smaller average pore size, enhanced surface oxygen vacancies, increased Mn4+ concentration, and richer Brønsted acid. Reaction gas adsorbed species and intermediates on the catalyst surface were dynamically captured during In situ DRIFTS experiments. The CO-SCR reaction of the catalyst was found to follow the E-R mechanism below 200 ℃ and the L-H mechanism at 200–350 ℃.