Gas-phase hydrogenation of acetonitrile on zirconium-doped mesoporous silica-supported nickel catalysts

Nickel supported on zirconium-dopedmesoporous silica catalysts, with varying nickel loadings (4-26 wt.%), were evaluated in the gas-phase hydrogenation of acetonitrile. Prier to the catalytic study, the catalysts were characterised by using XRD, XPS, HREM, H-2-TPR, N-2 adsorption-desorption a 77 K, H-2 and O-2) chemisorption and NH3-TPD. The catalytic activity, at 408 K, was shown to be influenced by the incorporation procedure of nickel. The catalyst prepared by ion exchange being the one which exhibits the best catalytic performance. In the steady state, the turnover frequency value decreases from 0.020 to 0.004 mol CH3CN converted at-g(Ni)(-1) s(-1) as the nickel-supported content increases from 4 to 26 wt.%, but reaches the highest value (0.033 mol CH3CN converted at-g(Ni)(-1) s(-1)) for the nickel-exchanged catalyst. The selectivity, in all cases, is higher\ toward ethylamine (37-67 mol%), especially for higher nickel loadings. The studied catalysts deactivate during the catalytic reaction, and the extent of deactivation depends on both the nickel loading and the nickel incorporation method. However, the conversion and selectivity patterns of these catalysts can be completely restored after treatment with Hi at 673 K for 1 h. (C) 2002 Elsevier Science B.V. All rights reserved.