Hydrogenation of Benzene over Catalyst Prepared from Amorphous Pt-Zr Alloy

Abstract

The hydrogenation of benzene in a fixed-bed type reactor operated at atmospheric pressure over amorphous Pt–Zr alloys with different platinum composition (Pt₂₀Zr₈₀, Pt₂₈Zr₇₂, Pt₃₂Zr₆₅) produced by a rapid solidification technique was investigated. Although the catalytic activity of the alloys was very low at virgin state, it gradually increased with increasing number of regeneration (oxidation and reduction)-reaction cycles. The activity approached a constant value after 5 or 6 regenerations. The hydrogenation activity of Pt–Zr alloy is higher than those of Pd–Zr and Ni–Zr alloys with the same composition. Furthermore, the turnover frequency of Pt–Zr defined as the reacting molecule per active site per second is also higher than those of Pd–Zr and Ni–Zr alloys. The hydrogenation order of the turnover frequency in the present study is almost the same as the order of the hydrogenation of olefins over the corresponding catalysts prepared from impregnation method. The characterization of the platinum catalyst prepared from the amorphous alloy revealed that the dispersion of platinum is higher than the impregnated catalysts, even though the platinum content of the former catalyst is much higher than that of latter. It is considered that this is a remarkable feature of the amorphous alloy catalyst.