Process for the preparation of silver catalysts for the production of ethylene oxide

In a process for the preparation of a supported silver catalyst containing alkaline earth metals and alkali metals as promoters suitable for the production of ethylene oxide by the oxidation of ethylene with gaseous oxygen or oxygen containing gases, the improvement comprising said catalyst preparation process comprising the following steps:

• (a) depositing in an evacuated container a suspension of silver oxide and an aqueous solution of an organic silver salt on a porous refractory substrate, the molar ratio of the silver in the silver oxide to the silver in the silver salt being from about 35 to 65% while periodically decreasing the vacuum;
• (b) drying the deposited silver compounds and porous refractory of (a) in a thin moving bed in an inert gas atmosphere at temperatures between about 50.degree. and 150.degree. C. to form an interim product;
• (c) depositing in said evacuated container a second suspension of silver oxide and a second aqueous solution of an organic silver salt on said interim product, the molar ratio of the silver in the silver oxide to the silver in the silver salt being from about 35 to 65%, said second suspension and said second aqueous solution suspension additionally containing compounds of barium and cesium or rubidium or a mixture of cesium and rubidium in sufficient amounts that the finished catalyst contains from about 0.01 to 0.25% by weight of barium and from about 0.001 to 0.05% by weight of cesium or rubidium or a mixture of cesium and rubidium, calculated as metals;
• and
• (d) activating the twice deposited silver compounds at temperatures of about 160.degree. C. to 270.degree. C. in a thin moving bed and in the presence of not more than about 8% oxygen.