Low temperature reaction mechanism of NH3-SCR reaction on MoOx modified CePO4 catalyst: Combination study on experiments and DFT calculations

Abstract

Developing CePO4-based NH3-SCR catalysts with high NOx conversion, N2 selectivity, and SO2 tolerance at low temperatures is challenging. Analyzing the atomic-level surface structure of these catalysts is particularly important. Hence, we conducted a combined computational and experimental study to design the surface structure of MoxCe1-xPO4 catalysts, corroborate the reaction performance and structural sensitivity, and investigate the relationship between active sites and structural performance at the atomic level. DFT calculations were used to systematically investigate the NH3 and NO adsorption capacity of the Mo-doped CePO4 solid solution structure model. The rationality of using the Mo-doped CePO4 solid solution structure as a catalyst was further supported by DFT calculation data and experimental results from BET, XRD, Raman, SEM, TEM, HR-TEM, NH3-TPD, H2-TPR, XPS and in situ DRIFTS. The source of the excellent intrinsic NH3-SCR activity of the Mo-doped CePO4 solid solution structure is disclosed. The role of the Mo dopant in the Mo-doped CePO4 solid solution as an SO2 trapping site to protect the catalytic active site from sulfation is discussed from a molecular perspective.