Enhancing H2 activation over Pt-WOx/SiO2 via IrO2 interface engineering for selective glycerol hydrogenolysis

Abstract

Catalytic hydrodeoxygenation of oxygenated compounds is of great importance to the sustainable production of biofuels and fine chemicals. Pt-based bifunctional catalysts exhibit excellent performance owing to their high efficiency in H₂ activation and subsequent hydrogen spillover, which enables them widely applied in biomass-derived oxygenate conversion. However, given the high cost of Pt, enhancing the hydrogenation activity of individual Pt sites is essential for improving overall catalytic efficiency and maximizing noble metal utilization. Herein, we report an IrO₂-modification strategy to enhance hydrogen activation over Pt-WO_x/SiO₂ catalysts for selective hydrogenolysis of glycerol. Structural characterizations reveal Ir incorporation induces the formation of Pt-O-Ir interface, which in turn promotes the generation of electron-deficient Pt^δ+ species. Diffuse reflection infrared Fourier transformed spectra of H₂ adsorption and Density functional theory calculations reveal that these Pt^δ+ sites promote hydrogen activation by significantly lowering the activation barrier for H₂ dissociation at the Pt-O-Ir interface. Catalytic performance tests confirm that the addition of 0.05 wt% Ir enhances the glycerol hydrogenolysis rate by 1.4-fold, while maintaining high selectivity toward 1,3-propanediol (56.1 %) at a glycerol conversion of 50.1 %. However, excessive Ir loading leads to partial coverage of Pt sites, reducing the number of accessible active centers and thus suppressing catalytic activity.