Deactivation of a commercial catalyst in the epoxidation of ethylene to ethylene oxide - Basis for accelerated testing

Abstract

An accelerated deactivation procedure for a commercial Ag-based catalyst for ethylene epoxidation was developed in a gradientless Berty-recycle reactor by increasing temperature and oxygen concentration which, however, were kept constant in the whole reactor for a single experiment. Thus, deactivation kinetics could be studied explicitly. The initial rates of both C 2 H 4 O and CO 2 formation and of ethylene consumption increase with reaction temperature and oxygen concentration. At 260°C increasing O 2 concentration favors the rate of ethylene oxide over that of CO 2 formation. Above 260°C the opposite is true. Catalyst activity decays faster at both higher reaction temperature and oxygen concentration. A correlation exists between the increase of the size of Ag particles and the catalyst activity decay, pointing to sintering as the main deactivation mechanism for this catalyst. Thus, by increasing these variables the catalyst deactivation process is accelerated. © 2004 Elsevier Inc. All rights reserved.