| 摘要 |
Disclosed are catalyst compositions comprising (i) one or more palladium group metals and/or compounds thereof; (ii) gold and/or compounds thereof; and (iii) optionally, an effective amount of one or more promoters selected from the group consisting of copper, nickel, cobalt, iron, manganese, lead, silver and compounds thereof. Preferably these catalyst compositions contain one or more promoters wherein the gram ratio of metal in the promoter to palladium group metal is up to about 0.4, wherein the catalysts are deposited on a support material and said support material is treated with one or more alkali metal bases and one or more alkali metal silicates prior to said deposition. Also described are processes for preparing ethylenically unsaturated esters comprising reacting in the vapor phase at least one olefinic compound with at least one carboxylic organic acid and molecular oxygen in the presence of an effective amount of the foregoing catalyst compositions.
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