A catalyst comprising palladium, gold, and a third metal; and a process for preparing vinyl acetate utilizing this catalyst

摘要

A catalyst comprising a porous support on the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold and a third metal. The catalyst is prepared by either method: A) Whereby a porous support is impregnated with an aqueous solution of water soluble salts of palladium and the third metal. The third metal is selected from magnesium, calcium, barium, zirconium and cerium as its oxide or mixture of oxide and metal. The palladium and third metal are fixed as a water insoluble compounds by reaction with an appropriate alkaline compound. The catalyst is then impregnated with a solution of a water-soluble gold salt. The gold is fixed in the solution as a water insoluble compound by a reaction with an appropriate alkaline compound. The fixed palladium and gold are reduced to their metallic state and the fixed third metal to its oxide or mixture of oxide and metal. B) Whereby the support is impregnated with a solution of water-soluble salts of palladium, gold and said third metal. The third metal is selected from magnesium, calcium, barium, and cerium as its oxide or mixture of oxide and metal. The palladium, gold and third metal are fixed in the solution as a water-insoluble compounds by rotating and/or tumbling the impregnated support while it is immersed in a solution of an appropriate alkaline compound. The fixed palladium and gold are reduced to their metallic state and the fixed third metal to its oxide or mixture of oxide and metal. Also described is a process for the production of vinyl acetate by reacting ethylene, oxygen and acetic acid whereby the reactants are contacted with the catalyst prepared by methods A or B above.