(239b) Designing Catalysts Using Predictions of Hydrocarbon and Oxygenate Adsorption Energies

Oxygenates and hydrocarbons are important in most catalytic processes, such as alcohol oxidation, biomass conversion, petrochemical production, fuel cells, Fischer-Tropsch synthesis, and CO₂ electroreduction. The heterogeneous catalysts used in these processes are generally found through a trial-and-error process. Given the immense combinatorial space for multimetallic surfaces, more efficient design paradigms are needed. Adsorption energies have been shown to be good predictors of catalytic performance; hence, efficient predictions of adsorption energies could greatly improve catalytic design.

We have developed an accurate model for predicting adsorption energies of hydroxyl and methyl in the top site from electronic structure parameters. This model uses the d-band center, p-band center, matrix coupling element, d-band filling, and electronegativity of the surface. These quantities are readily available from density functional theory (DFT) calculations, and can also be estimated directly from alloy structures. Simple relations based on metallic parameters can also be used to predict the energy of translating these species to more highly coordinated sites. Hence, these relations allow very efficient screening of surfaces for their adsorption properties.

We have also developed accurate scaling relations that allow prediction of adsorption energies of other oxygenates and hydrocarbons from the adsorption energies of hydroxyl and methyl. For example, the adsorption energy of longer alkyls can be predicted using methyl’s adsorption energy as well as gas-phase bond energies. Previous scaling relations among C₁ hydrocarbons have been made more accurate by scaling between these adsorbates in the sites where the tetravalency principle is fulfilled. These relations allow efficient prediction of potential energy surfaces for a variety of reaction pathways based on adsorption energies calculated from electronic structure parameters or calculated using DFT.

Together, these relations allow the rational design of a catalyst based on electronic structure parameters, as well as efficient screening from DFT calculations. Hence, we have carried out a comprehensive search for surfaces that catalyze alcohol oxidation, the oxygen reduction reaction, and alkane reforming.