Hydrogen Chemisorption on Potassium Promoted Supported Ruthenium Catalysts

The interaction of hydrogen on potassium promoted catalysts prepared by both sequential and co-impregnation methods was studied by proton NMR spectroscopy. Potassium addition decreased the amounts of both hydrogen adsorbed on the metal (site blocking) and the support hydroxyl groups. No evidence for a ruthenium-mediated (through-metal) electronic interaction between potassium species and adsorbed hydrogen was found. During catalyst preparation, potassium was incorporated on the support by an exchange with the Si(OH) groups forming Si(OK) species, thereby reducing the amount of surface silanol protons. The sequential impregnation technique proved to be more efficient in depositing potassium on the metal surface.