Silver catalyst for production of ethylene oxide from ethylene and process for producing the catalyst

A catalyst for the production of ethylene oxide from ethylene, said catalyst comprising a porous carrier composed of a molded article of a refractory material and having thereon (i) silver grains and (ii) as a cationic component, at least one alkali metal element selected from the group consisting of lithium, sodium, potassium, rubidium and cesium, wherein

• (A) silver is distributed on the outside surface of the carrier and on the inner surfaces of the pores of the carrier,
• (B) silver grains distributed on the inner surfaces of the pores of the carrier have an average diameter of 0.05 to 0.2 micron,
• (C) the loading (S) of silver on the outside surface layer of the catalyst and the loading (I) of silver on the innermost layer of the catalyst satisfy the following formula (1):
• I.gtoreq.0.7S (1)
• in which the said outside surface layer of the catalyst denotes a portion having a weight of about 5% by weight on average, in the range of about 4-6%, shaven as uniformly as possible from the ouside surface of one catalyst particle toward its inner layer when the weight of one catalyst particle is taken as 100%, and said innermost layer of the catalyst denotes an inner layer of the catalyst particle which is left after about 60% on the average, in the range of about 50 to 70%, has been shaven off from the outside surface of the catalyst particle toward its inner layer as uniformly as possible, and
• (D) the loading (Sc) of the alkali metal element as the cationic component on the outside surface layer of the catalyst and the loading (Ic) of the alkali metal element as the cationic component on the innermost layer of the catalyst satisfy the following formula (2-1) or (2-2):
• Ic.gtoreq.0.4Sc (2-1)
• in the case where the alkali metal is sodium or lithium
• Ic.gtoreq.0.6Sc (2-2)
• in the case where the alkali metal is potassium, rubidium or cesium, in which said outside surface layer of the catalyst and said innermost layer of the catalyst are as defined above.