ETHYLENE EPOXIDATION IN A CATALYTIC PACKED-BED MEMBRANE REACTOR

The performance of different membrane reactors for the epoxidation of ethylene was compared with that of a conventional fixed-bed reactor (F BR), under identical overall reaction conditions, using a cesium-doped silver catalyst supported on rx-alumina. Two packed-bed membrane reac tor configurations were used, one using oxygen as permeate with ethyle ne flowing over the catalyst bed (PBMR-O), and the other using ethylen e as permeate with oxygen Rowing over the catalyst bed (PBMR-E). The s tudy of the FBR showed that high oxygen/ethylene ratio increases ethyl ene oxide selectivity. The behavior of the membrane reactor was differ ent depending on the configuration, with the PBMR-O exhibiting smaller and the PBMR-E larger ethylene oxide selectivity, as compared to the FBR. While maintaining the overall reaction conditions fixed, ethylene oxide production in the membrane reactor could be increased further b y manipulating the residence time of the reactants over the catalyst b ed, and the maximun value was obtained for the largest possible reside nce time. The results demonstrate the operational flexibility and pote ntial attractiveness of membrane reactors, since local reactant concen trations and residence times can be tuned to optimize reactor performa nce. (C) 1998 Elsevier Science Ltd. All rights reserved.