Insight into H₂ adsorption and activation over Pt-WO_x sites for glycerol efficient hydrodeoxygenation

Pt-WO_x-based catalysts, known for their bifunctional nature, have shown promise in selective hydrodeoxygenation (HDO) reactions. Gaining insights into the activation process of H₂ and the origin of Brønsted acidity on Pt-WO_x sites is essential for enhancing reaction performance. In this work, we have developed a methodology to meticulously regulate the domain size of WO_x species on SBA-15 supported by utilizing the in-situ hydrolysis of WCl₆ with the hydroxyl groups on SBA-15. This approach allowed us to achieve different polymeric degrees of WO_x species on SBA-15. Notably, the low polymeric WO_x species associated with Pt, demonstrated significantly augmented catalytic activity in glycerol hydrogenolysis to 1,3-propanediol. The adsorption and activation of H₂ on such catalysts were systematically examined using in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). It was found that the Pt-WO_x interface facilitates the heterogeneous dissociation of H₂, generating hydride species (W-OH^δ+) that act as Brønsted acid sites, thereby enhancing catalytic activity. Our findings offer a new perspective on understanding the HDO reaction mechanism and provide valuable insights for the development of highly efficient catalysts for such reactions.