States of adsorbed hydrogen and their effect on the reaction of CO oxidation on Pd and Ta

Various states of hydrogen are identified on the foil and film surfaces of palladium and tantalum by photoelectric, conductivity, and thermal desorption methods. They are formed in the course of H 2 diffusion through a membrane and in the course of adsorption from the gas phase. The effect of an ethylene pyrolysis product, pyrocarbon, on the activity in CO oxidation on the palladium surface with and without H ads is determined. The presence of hydrogen is found to weaken the effect of pyrocarbon. A study of hydrogen adsorption on the tantalum foil showed that hydrogen adsorption drastically declines in the presence of chemisorbed CO, but the H-Ta binding strength doubles. The fact that the sorption ability of tantalum is completely restored upon CO adsorption and partially restored upon O 2 chemisorption is achieved by thermochemical treatment in hydrogen.