The influence of transition metal ions on the catalytic performance of Ru particles during the liquid phase hydrogenation of benzene to cyclohexene

The influence of some transition metal ions including Fe2+, Ni2+, Cr3+, Mn2+, Zn2+, Cd2+ on the catalytic performance of Ru particles during the liquid phase partial hydrogenation of benzene to cyclohexene was investigated in a titanium autoclave and a stainless steel autoclave. The Ru particles were prepared by the precipitation method. The catalysts were characterized using XRD, BET surface area measurement and XPS. The structure configurations and formation enthalpies of the hydrated metal ions, the complexes of the metal ions with benzene and cyclohexene as well as the complexes of hydrated metal ions with benzene and cyclohexene were optimized and evaluated using quantum chemical calculation methods. It was found that the poisoning effect of the transition metal ions on the catalytic activity of Ru particles only partially obeys the “Maxted rule”. The enhancing effect of the transition metal ions on the cyclohexene selectivity is associated with both the interaction of the metal ions with the active sites on Ru surface and with the tendency of metal ions to form hydrated complexes. In the stainless steel autoclave, the Fe2+, Ni2+ and Cr3+ resulted from the corrosion of the stainless steel have a synergetic effect with Zn2+, leading to a higher selectivity to cyclohexene.