EFFECTS OF 1,2-DICHLOROETHANE ADDITION ON THE OPTIMAL SILVER CATALYSTDISTRIBUTION IN PELLETS FOR EPOXIDATION OF ETHYLENE

The issue of optimal catalyst distribution was studied experimentally for the ethylene epoxidation reaction network on a Ag/alpha-Al2O3 cata lyst in the presence of 1,2-dichloroethane (DCE). For a fixed amount o f silver the influence of location and width of the catalytic layer on the conversion of ethylene, and on the selectivity and yield to ethyl ene oxide, was investigated for different concentrations of DCE (0-2 p pm) using a single-pellet reactor. Two levels of ethane in the feed (0 and 0.5 vol%) and a temperature range between 210 and 270 degrees C w ere studied. Depending an the experimental conditions, promotion, inhi bition, and poisoning effects of DCE were observed. The catalyst distr ibution and the concentrations of DCE and ethane in the feed, which pr ovide high selectivity and yield, were identified. XPS analysis was al so conducted to determine the state and composition of the silver cata lyst, both prior and subsequent to reaction. (C) 1998 Academic Press.