Elaborating the improving SO2 resistance mechanism of CeWTi catalysts through framework confined ordered mesoporous structures for low-temperature NH3-SCR reaction

Abstract

It is still a significant challenge that enhancing SO2 tolerance on the Ce-based catalyst in NH3-SCR reaction at low temperature. In this paper, an ordered mesoporous Ce-W-Ti-E catalyst with a framework confined structure had been constructed. The active components were directly constrained in the ordered mesoporous TiO2 structure, forming the framework confined ordered mesoporous structure. The ordered mesoporous structures in the framework structure provided better specific surface area and abundant active sites for the catalyst. In addition, the confinement effect of the framework structure enhanced the interaction between Ce, W and Ti, thus speeding up the electron transfer efficiency and enhancing the redox capacity of the catalyst. Furthermore, the introduction of W also supplemented a large amount of surface acid sites, which can inhibit the adsorption of SO2 on the catalyst surface, reduce the deposition of sulfate and well protect the active sites from SO2 attack with the help of special confinement effect. Therefore, the framework confined structure Ce-W-Ti-E catalyst in the whole process of SCR showed a wide operating temperature window, better stability and strong sulfur resistance, thus extended the catalyst lifetime in the NH3-SCR process.