A NICKEL TETRA-COORDINATED COMPLEX AS CATALYST IN HETEROGENEOUS HYDROGENATION

The [NiCl2(NH2(CH2)(12)CH3)(2)] complex supported on gamma-Al2O3 produ ces a catalyst which is considerably more active and sulfur-resistant for the hydrogenation of cyclohexene carried out in mild conditions th an a conventional catalyst obtained from acid solutions of NiCl2 and e ven than the same complex unsupported. As determined by XPS, the activ e species is the complex itself, which is stable under the reaction co nditions. The higher sulfur-resistance is attributed to electronic and geometrical effects. The catalyst system is considerably more resista nt to poisoning with thiophene than with tetrahydrothiophene. (C) 1998 SCI.