States of hydrogen adsorption on platinum-alumina and platinum-ceria catalysts : A temperature-programmed desorption study

摘要: Abstract The states of hydrogen adsorbed on reduced platinum-alumina and platinum-ceria catalyst were investigated by a temperature-programmed technique, either under flow pure argon (TPD experiments), or diluted in (TPDH experiments). TPDH experiments lead to more well resolved peaks comparison with the classical TPD experiments. first peak time profile, at ca. 220°C for 120°C is attributed desorption surface metal particles. metallic dispersion, deduced from infrared spectroscopy volumetric measurements, good agreement integration this peak. Hydrogen chemisorption sub-surface layers platinum crystallites also postulated. Dissociative cerium-oxygen bridges ceria support occurs temperatures between 290 325°C. amount stored can greatly exceed quantities bonded phase depending noble loading. measurements allow determination accessible area supported onto ceria.