Cu/Al2O3 catalysts modified with Pd for selective acetylene hydrogenation

• CuPd bimetallic catalysts prepared with a Cu rich surface.
• Evidence of hydrogen dissociation on Pd and spillover onto Cu surface.
• Selective hydrogenation of acetylene at industrially applicable temperatures.
• 80% ethylene selectivity at >99% conversion at only 363 K.
• Ready replacement for industrial PdAg catalysts.

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 H2: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 H2 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.

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