Styrene hydrogenation on supported Pd, Fe and Pd-Fe/γ-Al 2O 3 catalysts

Abstract

Bimetallic Pd-Fe/γ-Al 2O 3 catalysts with different concentration of palladium and 1 wt.% of iron were prepared via impregnation of Pd/γ-Al 2O 3 catalysts with Fe(NO 3) 3 solution and compared with corresponding monometallic Pd and Fe catalysts. The state of the supported components was studied by hydrogen chemisorption, ESR and Mössbauer spectroscopy; hydrogenation of styrene was also used as a test reaction. The hydrogenation was shown to proceed selectively to ethylbenzene on monometallic Pd catalysts and unselectively to the mixture of ethylbenzene and ethylcyclohexane on the Fe catalysts. Presence of 0.1 wt.% of palladium in the Pd Fe catalysts directed the hydrogenation exclusively to ethylbenzene while selectivity drops again upon increasing Pd loading to 0.3 and 0.5 wt.%. Possible reasons for such a non-trivial effect from the second metal are discussed.