Enhanced NO reduction on CePO catalysts: Cu-loading, phosphotungstic acid, and insights from In-situ DRIFTs and DFT.

This study investigates the effects of varying Cu/Ce doping ratios on the NH-SCR denitrification efficiency using Cu-HPW/CePO catalysts, where CePO serves as the support and copper-doped phosphotungstic acid (HPW) acts as the active phase. The NH-SCR reaction mechanism was studied by In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (In-situ DRIFTs) and Density Functional Theory (DFT). In-situ DRIFTs were employed to delve into the intricacies of adsorption and transformation dynamics at the surface sites of catalysts. This approach furnished a robust theoretical foundation aimed at augmenting the efficacy of low-temperature denitrification catalysts. DFT calculations were used to systematically investigate the reaction pathways, intermediates, transition states, and energy barriers over the HPW structure model to complete the NH-SCR reaction. Empirical evidence suggests that modifying the catalysts with copper substantially enhances their denitrification efficacy and extends their operational temperature spectrum. A notable initial increase in denitrification efficiency was observed with increasing levels of copper modification, followed by a decline. Within the HPW-O15H site, the NH-SCR reaction advances through both the E-R and L-H mechanisms, encompassing processes such as NH adsorption, intermediate formation and transformation, and product release.