(378e) Computational Characterization and Screening of Metal Phosphidesfor Ethane Dehydrogenation

Metal phosphides (MPs) are strongly ordering and present metal ensembles similar to those of metal alloys, making them of potential interest as catalysts for reactions that must be carried out at high temperature and for which the selectivity provided by small ensembles is critical, as in dehydrogenation of ethane. Computational screening of metal phosphides is complicated by the diverse stoichiometries and bulk structures of these materials. Further, phosphorus itself may not be innocent in surface reactivity, a feature that both increases the design space and complicates modeling. Here we report density functional theory (DFT) calculations across a range of metals and metal-to-phosphorus ratios to identify compositions of interest for ethane dehydrogenation (EDH). We choose common bulk structures and apply across a large range of metals to separate geometric from compositional effects on bulk and surface properties. We compute binding energies of probe molecules relevant to EDH and show that energies at both metal and phosphorus sites are sensitive to metal. We use these results to predict ensembles and compositions likely to provide good EDH selectivity and resistance to coking.