Deactivation Mechanism of Palladium Catalysts for Ethanol Conversion to Butanol

Abstract

Abstract: A Pd/Al2O3 catalyst (Pd = 0.1 wt%) for ethanol conversion to butanol deactivates within 10 h of service, despiteits high initial activity at 275°C. Probable deactivation mechanisms wereexplored, including poisoning ofPd/Al2O3 due to adsorption ofby-products on Pd, sintering of Pd phases, leaching of Pd from the catalyst,changes in the Pd electronic state, changes in the catalyst’s porous structure,and blockage of Al2O3 activesites. The Pd/Al2O3 deactivationwas found to be mainly caused by CO molecules that evolved during sidereactions. These molecules can either block Pd active sites due to the formationof strong Pd–CO complexes, or enter a CO disproportionation reaction to formcarbon deposits on Pd phases. The knowledge gained from this study can be usedfor the targeted modification ofPd/Al2O3 and the creation ofselective systems operating stably in the presence of by-products.