The Effect of Preparation of Ni/MgF_2 Catalysts on the Hydrogenation of Benzene Activity

摘要

The use of magnesium fluoride as a support for nickel has permitted us to obtain a catalyst of high activity and selectivity for hydrogenation of benzene to cyclohexane under atmospheric pressure. The effect of nickel content and metal precursor on the nickel catalysts surface structures and their catalytic behavior in the benzene hydrogenation reaction has been studied. A series of catalysts obtained by impregnation from different precursors, i.e. Ni(CH_3COO)_2, Ni(NO_3)_2 and NiCl_2 with Ni contents 0.5,1, 5 and 10 wt.% have been deposited on magnesium fluoride support. Their surface areas and pore size distributions were investigated using BET and BJH methods, respectively. Dispersion of nickel and the mean size of the crystallites have been determined on the basis of hydrogen chemisorption. The activity of the catalysts in the hydrogenation reaction of benzene at 75-225℃ under atmospheric pressure was measured. The results show that the maximum activity was obtained at 175℃ for all catalysts. The activity of the catalysts in benzene hydrogenation was found to strongly depend on the precursor of Ni and increases with increasing dispersion. From the nickel catalysts supported on MgF_2 the one based on nickel acetate was the most active.