氢解
化学
铜
催化作用
无机化学
吸附
粒径
一氧化二氮
一氧化碳
氧化物
光化学
有机化学
物理化学
标识
DOI:10.1016/0021-9517(91)90334-z
摘要
Silica-supported copper particles of high thermostability have been subjected to oxidation-reduction treatments after which the metal particle size, the surface structure, and the catalytic hydrogenolysis of methyl acetate were investigated. The metal particle size was assessed from the dissociative adsorption of nitrous oxide, X-ray line broadening, and transmission electron microscopy. The surface structure of the copper particles was derived from infrared spectra of adsorbed carbon monoxide. The hydrogenolysis of methyl acetate was used as a structure-sensitive test reaction to illustrate the effect of the surface structure on the activity of the catalyst. The copper particle size is not affected by reduction treatments up to 873 K, whereas the surface structure of the copper particles and thereby the oxygen uptake during dissociative adsorption of nitrous oxide and the activity of the catalyst in the hydrogenolysis of methyl acetate strongly depend upon the temperature and duration of the reduction treatment. Without a change of the copper particle size, prolonged reduction of the catalyst results in more densely packed copper surfaces that are more susceptible to penetration of oxygen during passivation with nitrous oxide and less active in the hydrogenolysis of methyl acetate. The rearrangement of the surface structure of the copper particles is reversible upon repeated oxidation-reduction cycles.
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