Activity decay of potassium-promoted iron oxide catalyst for dehydrogenation of ethylbenzene

Abstract

The decay of activity of a commercial potassium-promoted iron oxide catalyst for ethylbenzene dehydrogenation was examined continuously over a period of about 1000 h at 630, 640 and 650°C in the presence of steam using a differential reactor. Initially, the activity of the catalyst decreased slowly and the deactivation rate was gradually increased. On the basis of information obtained from physico-chemical analysis of the used catalyst samples, it is speculated that the gradual loss and migration of potassium promoter from the surface of the catalyst pellet is the major cause of the decay in catalytic activity. A deactivation kinetic model is presented which is based on a decrease in the potassium promoter with process time. This kinetic model was in fair agreement with the experimental data relating to catalyst deactivation.