SILVER-BASED CATALYST FOR VAPOR PHASE OXIDATION OF OLEFINS TO EPOXIDES

摘要

This invention relates to a process of oxidizing an olefin having at least three carbon atoms directly to the corresponding epoxide comprising contacting the olefin with oxygen in the presence of a catalyst comprising a mixed silver-promoter metal (+2 or +3) silicate. In the direct oxidation of propylene the process yields a high selectivity to propylene oxide. This invention also relates to a catalyst and the process for preparing said catalyst. The process comprises contacting in an aqueous solution the dissolved salts (a) a silver-containing salt; (b) at least one salt containing a multivalent cation promoter; and (c) a silicon-containing salt, wherein the mole ratio of silicon to combined silver and promoter metals is at least 0.5, under conditions sufficient to form a mixed silver-promoter silicate precipitate.