Kinetic modelling of the NOx reduction by H2 on Pt/WO3/ZrO2 catalyst in excess of O2

Abstract

This paper addresses the elementary kinetic mean field modelling of the NOx reduction by H2 on Pt/WO3/ZrO2 under oxygen-rich conditions. Pt/WO3/ZrO2 was recently shown to reveal substantial low-temperature deNOx activity with enhanced N2 selectivity referred to traditional Pt catalysts. The model was developed based on a postulated reaction mechanism as well as kinetic examinations and implied a network of 48 reaction steps described by Arrhenius-based rate expressions. Kinetic parameters were taken from literature and by fitting calculations, while pre-exponential factors of adsorption were estimated from kinetic gas theory. For validation, experiments were simulated and thermodynamic consistency was proven by checking the Gibbs free enthalpy of the catalytic surface reactions. As a result of the kinetic model, the formation of OH surface species was identified as the rate determining step of H2 oxidation, while the reduction of NO predominately occurs by dissociation of chemisorbed NO.