Oxidative Dehydrogenation of Ethylbenzene to Styrene with Carbon Dioxide over Fe2O3/TiO2–ZrO2 Catalyst: Influence of Chloride

This study was undertaken to know the influence of chloride ions in TiO2–ZrO2 mixed oxide and to explore chloride containing Fe2O3/TiO2–ZrO2 catalyst for oxidative dehydrogenation of ethylbenzene to styrene utilizing carbon dioxide as a soft oxidant. The TiO2–ZrO2 mixed oxide was synthesized by a co-precipitation method. Over the calcined support, a nominal 15 wt.% Fe2O3 was deposited by a wet impregnation method. The prepared catalysts were characterized using X-ray diffraction, temperature programmed desorption of NH3 and CO2, scanning electron microscopy and BET surface area methods. The catalytic activity measurements were made in a fixed-bed microreactor under normal atmospheric pressure. Characterization studies reveal that chloride ions exhibit a strong influence on the physicochemical and catalytic properties of the titania–zirconia composite oxides. The impregnated iron oxide was found to be in a highly dispersed form over the TiO2–ZrO2 support and influenced greatly on its acid–base properties. The chloride containing Fe2O3/TiO2–ZrO2 catalyst exhibited better activity and selectivity. The order of activity on various samples was found to be Fe2O3/TiO2–ZrO2 (chloride) > TiO2–ZrO2 (chloride) > TiO2–ZrO2.