Inelastic neutron scattering study of the H2 interaction with carbon-supported Pt and Pd catalysts

Abstract

Carbon-supported Pt and Pd catalysts are largely employed as heterogeneous catalysts for hydrogenation reactions. Albeit their routine use in industry, many details about their interaction with H2 are still not completely understood. In this article, we propose a detailed investigation of the behavior in the presence of H2 of an activated carbon and of two catalysts obtained by depositing on it Pt and Pd nanoparticles by means of Inelastic Neutron Scattering (INS) spectroscopy. The high-quality INS spectra of the three samples were measured in absence and in presence of different amounts of H2, providing very detailed information about H2 physisorption on each system and about the nature of the metal hydrides formed upon hydrogenation of the catalysts. In addition, we were also able to obtain a direct observation of the occurrence of hydrogen spillover from the metal nanoparticles onto the activated carbon, as revealed by the increase of the number of C-H species at the borders of the graphenic domains. Overall, this work provides important insights for better understanding the complex nature of the interaction between H2 and Pt and Pd-loaded activated carbon catalysts.