Pt-WOx/C Catalysts for α, β-Unsaturated Aldehydes Hydrogenation: An NMR Study of the Effect of the Reactant Adsorption on Activity and Selectivity

Abstract

The selective hydrogenation of alpha,beta-unsaturated aldehydes is an ideal case for studying the structure-activity relationships in heterogeneous catalysis. In particular, cinnamaldehyde can be used as probe molecule for revealing the competition between hydrogenation of C=C and C=O bond. Here, we investigated the effect of the modification of some Pt supported on carbon catalysts by WOx species in cinnamaldehyde hydrogenation, as WOx species are reported to increase the adsorption and activation of the C=O group of alpha, beta-unsaturated aldehydes. Classical techniques used for correlating the catalyst activity and the selectivity to the characteristic of the materials (XRD, HAADF-STEM, XEDS mapping and XPS) have been coupled with NMR relaxometry, as innovative application, to disclose how the molecule approaches the catalyst surface. This indeed constitutes a crucial aspect that rule the catalytic activity. Therefore, an innovative, holistic approach has been used to consider the whole catalytic system.