Catalysis of ultrafine CuB catalyst for hydrogenation of olefinic and carbonyl groups

Ultrafine catalysts of CuB and Me-CuB (Me: Cr, V, La, Th, Zn) were prepared by the chemical reduction method and were characterized. Their catalytic p roperties for hydrogenation on monofunctional (olefinic and carbonyl) and b ifunctional (conjugated and nonconjugated) compounds were also studied and compared with those of a commercial catalyst of copper chromite. For the hy drogenation of monofunctional compounds over CuB catalyst, the reactivities were in the following order: C=O (in aldehyde) > C=O (in ketone) >> C=C. T he reactivity of C=C was largely enhanced by its delocalization with conjug ated C=C or C=O group. In general, the additives of Cr, V, La, Th and Zn in creased the dispersion of copper in CuB catalyst and promoted the reduction of C=O group. The additive of Cr only slightly affected the reduction of m onofunctional C=C group, but effectively promoted the reduction of C=O grou p. However, the additive of Cr also effectively promoted the reduction of C =C group which was conjugated with C=O or another C=C group. The ultrafine catalysts of Cr-CuB containing a much lower content of chromium (Cr < 5 mol %) were more active than the commercial copper chromite (Cr > 50 mol%). The se Cr-CuB catalysts are highly promising for replacing copper chromite for liquid-phase hydrogenation reactions. (C) 2000 Elsevier Science B.V. All ri ghts reserved.