Increase in Activity of Doubly-Promoted Iron Oxide Catalyst for Dehydogenation of Ethylbenzene by Reduction

Abstract

A study has been made of the effect of reduction of a Fe₂O₃ catalyst doubly-promoted with Al₂O₃ and K₂O on its ability to catalyze ethylbenzene dehydrogenation. Reducing gases used were hydrogen, CH₃OH, HCHO and CO. Reducing temperatures were ranged from 400 to 530°C. Activity tests were carried out at 460∼500°C in a flow system.
Reduction by those gases caused to increase in the catalytic activity and selectivity of the catalyst. The most effective reducing agent was found to be CO (Fig.6). X-Ray analysis showed that iron existed primarily as Fe₃O₄ and γ-Fe₂O₃ in the reduced catalysts while as α-Fe₂O₃ in an unreduced one.
The catalytic activities of the reduced catalysts for styrene formation paralleled approximately with the content of crystalline γ-Fe₂O₃ rather than with that of crystalline Fe₃O₄ (Fig.7).