PROCESS FOR PREPARING AN EPOXIDATION CATALYST

A process for preparing a catalyst for producing ethylene oxide by gas-phase oxidation of ethylene comprises i) impregnating a porous alumina support having a packed tube density in the range of 100 to 450 g/L; a Log differential pore volume distribution curve, 5 as measured by mercury porosimetry, having at least one peak in a pore diameter range of 0.01 to 5.0 µm; and a BET surface area in the range of 1.5 to 30.0 m2/g; with a silver impregnation solution, preferably under reduced pressure; and optionally subjecting the impregnated porous alumina support to drying; and ii) subjecting the impregnated porous alumina support to a calcination process; wherein steps i) and ii) are optionally repeated, 10 to yield a catalyst comprising at least 25 wt.-% of silver, relative to the total weight of the catalyst. The catalyst shows high activity and selectivity. The invention further relates to a catalyst for producing ethylene oxide by gas-phase oxidation of ethylene, obtainable by a process as defined above. The invention also relates to a catalyst for producing ethylene oxide by gas-phase oxidation of ethylene, comprising at least 25 wt.-% of silver, 15 relative to the total weight of the catalyst, deposited on a porous alumina support, the support having i) a packed tube density in the range of 100 to 450 g/L, preferably 150 to 450 g/L, more preferably 200 to 400 g/L; ii) a Log differential pore volume distribution curve, as measured by mercury porosimetry, having at least one peak in a pore diameter range of 0.01 to 5.0 µm; and iii) a BET surface area in the range of 1.5 to 30.0 m2/g, 20 preferably 1.5 to 20.0 m2/g, more preferably 2.0 to 10.0 m2/g, most preferably 2.5 to 8.0 m2/g, in particular 3.0 to 7.0 m2/g. The invention further relates to a process for producing ethylene oxide by gas-phase oxidation of ethylene, comprising reacting ethylene and oxygen in the presence of a catalyst as defined above. Le processus pour préparer un catalyseur de production d'oxyde d'éthylène par oxydation en phase gazeuse de l'éthylène comprend i) l'imprégnation d'un support d'alumine poreux ayant une densité de tube tassée dans la plage de 100 à 450 g/L; une courbe de distribution de volume de pore différentiel logarithmique, 5 telle que mesurée par porosimétrie au mercure, ayant au moins un pic dans une plage de diamètres de pores de 0,01 à 5,0 µm; et une surface BET dans la plage de 1,5 à 30,0 m2/g; avec une solution d'imprégnation d'argent, de préférence sous pression r