Periodic trends in the selective hydrogenation of styrene over silica supported metal catalysts

Abstract

The establishment of periodic trends is a powerful approach for rational design of heterogeneous catalysts. It deals with measuring or computing a physico-chemical descriptor of a solid which is correlated to the activity in a specific catalytic reaction. In this work, the metal–carbon bond energy (EMC), calculated in the M2C carbide phases was calculated as a bulk descriptor to predict the catalytic activity of metal supported catalysts for the selective hydrogenation of styrene. A set of different metals (Cu, Pt, Pd, Ir, Co, Ni, Ru and Rh) supported on silica were prepared and characterized. Experimental TOFs were measured in a semi-batch reactor. The TOF follows the order Pd>Rh>Ru, Pt, Ir>Ni>Co>Cu which differs from the well established hydrogenation of ethylene.We show that the metal–carbon bond energy (EMC) calculated by DFT from the corresponding M2C carbide bulk structure correlates the TOF of styrene hydrogenation over the 8 metal catalysts according to a double volcano curve. The predictive model indicates Pd is the most active monometallic phase and suggests quantitative guidelines for the rational design of very active catalyst compositions.