Strucutre-activity relationship of V/TiO2 catalyst: exploring by operando HERFD XAS the V5+/V4+ redox cycle in the NH3-SCR pathway

Vanadia-based catalysts are the system of choice for the selective catalytic reduction of nitrogen oxides with NH3 (NH3-SCR) in stationary plant applications.. Despite being largely studied, a comprehensive picture of the structure-activity relation at atomistic level for these catalysts is still under way. Furthermore, the NH3-SCR catalytic activity enhancement, due to the presence of HCl in the stationary plant exhaust feed, so far has been largely neglected. To rationalize the active sites oxidation state and redox dynamics, the local structure, and the reaction pathway, with this proposal we aim at systematically investigating a model V/TiO2 catalyst by operando XAS during NH3-SCR. We will focus on high-quality XANES and EXAFS data collection in reaction conditions, to determine the V5+/V4+ redox dynamics, the role of HCl and the coordination of the adsorbed reaction intermediates.