Ethylene versus ethane: A DFT-based selectivity descriptor for efficient catalyst screening

The production of ethylene without its hydrogenation to ethane is a challenge for several catalytic processes. Here, we present a catalyst screening scheme, where the Gibbs free energy difference between the ethylene hydrogenation barrier and ethylene desorption energy is defined as a descriptor for ethylene selectivity. Using plane-wave, dispersion-corrected DFT calculations, we evaluated the descriptor values over the (111) facets of Pt, Pd, and Cu as well as a series of Pt-and Pd-based bimetallic alloys. Our predicted descriptor values indicate that the addition of a Group IB metal (Cu, Ag, or Au) to Pt or Pd improves ethylene selectivity. Ag induces the most significant improvement at 50% while Au has the strongest effect at 75% atomic composition. Pd-based alloys exhibit superior ethylene selectivity over their Pt based counterparts. Our descriptor model offers an efficient method for the initial screening of catalysts with improved ethylene selectivity. (C) 2018 Elsevier Inc. All rights reserved.