Studies of the hydrogen held by solids: XVIII. Hydrogen and oxygen chemisorption on alumina- and zeolite-supported platinum

摘要: The chemisorption of H2 and O2 on Pt particles, supported alumina, was studied. Measurements made following sintering at successively higher temperatures showed that the values fell, while those for remained relatively constant or sometimes increased as surface area decreased. Areas estimated from electron micrograph particle size distributions properly reflected changes in metal area; did not. Hence, titration an oxygen covered with cannot be used to discriminate between average compositions PtH PtH2. micrographs were consistent 1:1 = HPt(surface) stoichiometry, however, even high dispersions where HPt(total) near unity. variable stoichiometry also complicates method determining areas, although error introduced probably exceed 16.7%. Three cases > 1 have been reported reinvestigated two shown dubious reliability. third, Pt-zeolite system, found more complicated than supposed not necessarily example H atoms held by each exposed Pt.