Silver catalysts, a process for their preparation, and their use in preparing ethylene oxide

Claim 1

A method for making a silver catalyst consisting essentially of 3 to 20 percent of silver and 0.003 to 0.05 percent of a promoter which is at least one of potassium, rubidium, and cesium, said percentages being by weight of said catalyst, present on a heat resistant porous support consisting of aluminum oxide having a specific surface area from 0.1 to 1 m 2 /g (as measured by the method of Brunauer, Emmett and Teller), which method comprises: (a) in a first impregnating step, simultaneously applying to said support from 55 to 85 percent by weight of the total amount of said silver and from 15 to 45 percent by weight of the total amount of said promoter in the form of an impregnating solution containing compounds of silver and of said promoter; (b) drying the impregnated support obtained in step (a); (c) in a second impregnating step, simultaneously applying to the dried support the remaining amount of said silver and of said promoter in the form of an impregnating solution containing compounds of silver and of said promoter; and (d) heating the impregnated support obtained in step (c) to reduce the applied silver compound to metallic silver.

Claim 2

A method for making a silver catalyst consisting essentially of 3 to 20 percent of silver and 0.003 to 0.05 percent of a promoter which is at least one of potassium, rubidium, and cesium, said percentages being by weight of said catalyst, present on a heat resistant porous support consisting of aluminum oxide having a specific surface area from 0.1 to 1 m 2 /g (as measured by the method of Brunauer, Emmett and Teller), which method comprises: (a) in a first impregnating step, simultaneously applying to said support from 55 to 85 percent by weight of the total amount of said silver and from 15 to 45 percent by weight of the total amount of said promoter in the form of an impregnating solution containing compounds of silver and of said promoter; (b) drying the impregnated support obtained in step (a); (c) in a second impregnating step, simultaneously applying to the dried support the remaining amount of said silver and of said promoter in the form of an impregnating solution containing compounds of silver and of said promoter; and (d) heating the impregnated support obtained in step (c) to reduce the applied silver compound to metallic silver.

Claim 8

A method for making a silver catalyst consisting essentially of 3 to 20 percent of silver and 0.003 to 0.05 percent of a promoter which is at least one of potassium, rubidium, and cesium, said percentages being by weight of said catalyst, present on a heat resistant porous support consisting of aluminum oxide having a specific surface area from 0.1 to 1 m 2 /g (as measured by the method of Brunauer, Emmett and Teller), which method comprises: (a) (i) simultaneously applying to said support the total amount of silver and from 15 to 45 percent by weight of the total amount of said promoter in the form of an impregnating solution containing compounds of silver and of said promoter in a single impregnating step, or (a) (ii) successively applying to said support the total amount of silver in the form of an impregnating solution containing a compound of silver in a first impregnating step and from 15 to 45 percent by weight of the total amount of said promoter in the form of an impregnating solution containing a compound of said promoter in a second impregnating step; (b) heating the impregnated support obtained in step (a) (i) to reduce the applied silver compound to metallic silver; (c) applying to the supported catalyst obtained in step (b) the remaining amount of said promoter in the form of an impregnating solution containing a compound of said promoter in a further impregnation step; and (d) drying the impregnated supported catalyst obtained in step (c).

Claim 9

A method for making a silver catalyst consisting essentially of 3 to 20 percent of silver and 0.003 to 0.05 percent of a promoter which is at least one of potassium, rubidium, and cesium, said percentages being by weight of said catalyst, present on a heat resistant porous support consisting of aluminum oxide having a specific surface area from 0.1 to 1 m 2 /g (as measured by the method of Brunauer, Emmett and Teller), which method comprises: (a) (i) simultaneously applying to said support the total amount of silver and from 15 to 45 percent by weight of the total amount of said promoter in the form of an impregnating solution containing compounds of silver and of said promoter in a single impregnating step, or (a) (ii) successively applying to said support the total amount of silver in the form of an impregnating solution containing a compound of silver in a first impregnating step and from 15 to 45 percent by weight of the total amount of said promoter in the form of an impregnating solution containing a compound of said promoter in a second impregnating step; (b) heating the impregnated support obtained in step (a) (i) to reduce the applied silver compound to metallic silver; (c) applying to the supported catalyst obtained in step (b) the remaining amount of said promoter in the form of an impregnating solution containing a compound of said promoter in a further impregnation step; and (d) drying the impregnated supported catalyst obtained in step (c).