Deactivation kinetics of Ag/Al2O3 catalyst for ethylene epoxidation

Deactivation kinetics of a commercial Ag/Al2O3 catalyst was investigated using accelerated deactivation tests in a Berty-type gradientless recycle reactor. Separability of catalytic reaction and deactivation kinetics were established by operation in a "deactivation compensation" mode, keeping temperature and oxygen concentration constant. It was shown that sintering is the main source for deactivation and that kinetics of deactivation can be described by using a general power-law equation with an order of deactivation equal to 1 with respect to the driving force (a - a(ss)), a being the time-dependent activity and a(ss) the final steady-state activity after an extended period of catalyst operation. The long-time prediction of catalyst behavior suggested that an improved catalyst should work at a lower temperature to avoid sintering. (C) 2004 Elsevier Inc. All rights reserved.