Effect of addition of Ce on Fe-K mixed oxide catalyst in dehydrogenation of ethylbenzene

Abstract

Dehydrogenation of ethylbenzene was evaluated with Fe-K and Fe-Ce-K mixed oxide catalysts to examine the addition effect of Ce. Fe-Ce mixed oxide was prepared by co-precipitation of Fe and Ce nitrate solutions. K 2CO3 was added to Fe oxide or Fe-Ce mixed oxide. Only a small amount of Ce addition, Ce/Fe = 3.0 × 10 -5 (atomic ratio), was effective to improve the dehydrogenation activity, but excess Ce addition, above Ce/Fe = 2.0 × 10 -3, did not further improve the activity. BET surface area measurement, SEM observation and XRD were performed before and after the dehydrogenation reaction. BET surface area was increased significantly by addition of Ce. However, the yield of styrene per unit surface area remained constant independent of the amount of Ce addition. SEM observation revealed that the particle size of Fe-Ce-K was smaller than that of Fe-K both before and after the reaction. We concluded that the addition of Ce retarded crystal growth of the mixed oxide, and improved the styrene yield by enlarging the surface area.