Reversibility of hydrogen chemisorption on a ceria-supported rhodium catalyst

摘要: Abstract This work reports on some new aspects of the chemistry hydrogen-ceria systems. It is shown that, at room temperature, in presence highly dispersed rhodium, ceria chemisorbs large amounts hydrogen. As deduced from magnetic measurements carried out situ , this spillover process leads to reduction an extent 21% total amount cerium ions present sample, which roughly equivalent complete surface oxide. found that over a hydroxylated sample induced by partly reversible even 295 K. If pumped off 773 K, initial oxidation state almost completely recovered. Both rate and hydrogen chemisorption were be sensitive specific pretreatment applied catalyst. Over bare ceria, 298 K was negligible, temperatures as high 473 being necessary activate process. In contrast rhodium-containing catalyst, pure desorption much larger water formation, thus revealing deeper irreversible