Catalysts for ethylene oxide prepn. - comprising supported silver promoted with two or more alkali metals

摘要

Catalysts for ethylene oxide prepn. from ethylene and O2 comprise Ag and alkali metals or their cpds. deposited on a support. The catalysts contain (a) 0.1-2 atom % Na and (b) either 0.05-0.35 atom % K, 0.003-0.25 atom % Rb, 0.0005-0.2 atom % Cs or a corresp. amt. of a mixt. thereof. All percentages are based on the Ag content. The Ag content is pref. 2-12 (esp. 5-10) wt.% based on the wt. of the catalyst. The catalysts are pref. prepd. by impregnating the support with an aq. soln. of an Ag complex salt (e.g. an Ag-amine carboxylate) and suitable alkali metal cpds. (e.g. hydroxides), steaming the resulting composite until the Ag cpd. decomposes, and calcining the product at 100-400 degrees C to constant wt. Other standard methods can also be used. The catalysts have higher activity and selectivity than conventional Ag catalysts promoted with alkali(ne earth) metals, and/or have a longer life.