Investigation into the effects of Ce element loading on Cu-SAPO-34 catalyst structure and performance

Abstract

Currently, one of the most significant technologies for lowering NO_x emissions from diesel engines is the selective catalytic reduction with ammonia (NH₃-SCR) technique, which uses ammonia as a reducing agent. The wide active temperature window, excellent nitrogen selectivity, and outstanding hydrothermal aging stability of NH₃-SCR catalysts are important given the real working circumstances of engines and the regeneration of DPF upstream of the SCR system. Cu-SAPO-34, a small-pore molecular sieve catalyst, has drawn a lot of interest because of its high-temperature hydrothermal aging stability and good low-temperature activity. One important problem that must be resolved, nevertheless, is Cu-SAPO-34’s low-temperature hydrothermal stability. The impact of loading the active element Ce on the catalyst’s performance and low-temperature hydrothermal stability was examined in this work. Three CuCe_x-SAPO-34 catalysts with varying Ce/Al molar ratios were created using a one-step synthesis process after varying Ce loading levels were established. According to the outcomes of performance assessment trials, the catalyst’s improved effect on the NO_x conversion rate is most noticeable when the Ce/Al ratio is 0.06 when compared to the catalyst without Ce. Multiple characterizations of the CuCe_0.06-SAPO-34 and Cu-SAPO-34 catalysts have revealed that loading a suitable amount of Ce can help the catalyst form a porous structure, improve the catalyst’s distribution of copper ions and acidic sites, increase the stability of its pore and surface structures, lessen aging-related deterioration, and allow the catalyst to have a large number of acidic sites and SCR active sites both before and after aging, all of which contribute to the catalyst’s excellent SCR performance.