Selective hydrogenation of benzene to cyclohexene in continuous reaction device with two reaction reactors in serie over Ru-Co-B/ZrO2 catalysts

Abstract

A Ru-B/ZrO 2 catalyst for selective hydrogenation of benzene to cyclohexene was prepared using a chemical reduction method. The effects of transition metals such as Cr, Mn, Fe, Co, Ni, Cu, and Zn on the performance of the Ru-B/ZrO 2 catalyst were investigated. It was found that the addition of these transition metals all increased the B content of the Ru-B/ZrO 2 catalyst. The modification of B, the ensemble effect, and the ligand effect of the second metal or metal oxide resulted in a decrease in the activity and an increase in the selectivity for cyclohexene of the Ru-B/ZrO 2 catalyst. When the atomic ratio of Co/Ru was 0.06, the Ru-Co-B/ZrO 2 catalyst gave a selectivity for cyclohexene of 82.8% and a cyclohexene yield of 62.8% at a benzene conversion of 75.8% at 25 min. Moreover, the benzene conversion was stable at around 40%, and the selectivity for cyclohexene and the cyclohexene yields stabilized at around 73% and 30%, respectively, in 419 h under the optimum reaction conditions in a continuous device with two reactors in series. The selectivity for cyclohexene and the cyclohexene yield were stabilized at around 73% and 30%, respectively, in 419 h over a Ru-Co-B/ZrO 2 catalyst in a continuous device with two reactors in series.