Cu/Al2O3 catalysts modified with Pd for selective acetylene hydrogenation

A Cu/alumina catalyst has been modified by addition of various quantities of Pd. Characterisation suggests formation of a bimetallic with the surface dominated by Cu. Optimisation of the Cu:Pd ratio (50:1) resulted in a catalyst which combined the properties of Cu and Pd (high ethylene selectivity and activity at low temperature). Using a 3:1 H-2:acetylene feed, >99% acetylene conversion and >70% ethylene selectivity was attained at 373 K, representing a considerable reduction in the temperature necessary to achieve equivalent activity/selectivity over monometallic Cu. Increasing the H2:acetylene ratio to 10 resulted in >99% acetylene conversion at 363 K as well as enhanced ethylene selectivity (>80%). Enhanced activity of Cu at low temperature is attributed to H-2 dissociation on Pd with spillover onto Cu sites where the reaction takes place. These bimetallic CuPd catalysts offer sufficient activity at low temperature and could represent a replacement to the current industrial PdAg catalysts. (C) 2014 Elsevier Inc. All rights reserved.