Process for preparing supported silver-containing catalysts and catalyst precursors and their use in the alkylene oxide production

摘要

A silver-containing supported catalyst is prepared by impregnation of the support with lactic acid containing silver, nitrate and optionally metal ion promoters. A silver containing and optionally promoted supported catalyst (I) is prepared by: (a) treatment of a support having a specific surface area of up to 1.5 m<2>/g with a silver, nitrate and optionally metal ion promoter containing lactic acid; (b) drying of the resulting treated support and pre-decomposition to the free form as well as in the lactic acid and nitric acid anionic form in an essentially oxygen free atmosphere whereby the drying is carried out at 50-120 degrees C and the pre-decomposition is carried out at 140-220 degrees C and optionally at 400-500 degrees C, with a heating rate of 70-150 degrees C/hour used in the two-step pre-decomposition for the transition between the two temperature ranges; and (c) activation of the resulting catalyst intermediate by heating in an oxygen containing atmosphere at 130-450 degrees C at 3-8 degrees C/hour and 0.4-21 vol.% oxygen in such a way that the exhaust gas has a CO2 content of no more than 2, preferably 1 vol. %. An Independent claim is included for a catalyst intermediate from step (b) that has been cooled in an essentially oxygen-free atmosphere to no more than 70-80 degrees C.