Screening the activity of Lewis pairs for hydrogenation of CO2

CO2 capture coupled with CO2 conversion to hydrocarbon fuels could reduce the overall anthropogenic carbon footprint but requires an efficient catalytic pathway for CO2 hydrogenation. In this work, we examine functional groups that can be integrated within nanoporous materials, such as metal organic frameworks, that could lead to the development of materials that can selectively adsorb CO2 from flue gas and convert it into a useful fuel. We focus on the use of Lewis pair (LP) moieties as catalytic functional groups because of their activity for heterolytic dissociation of H2 and subsequent hydrogenation of CO2. However, most LP functional groups also strongly bind CO2, such that the catalytic site can be poisoned if the binding energy of CO2 is much stronger than that of H2. In this work, we screen a variety of LP moieties using density functional theory to compute the adsorption energies of H2 and CO2. We consider five classes of LP functional groups, with each class designed to explore modifying the binding energies in different ways. We have developed a mathematical model for predicting the H2 adsorption energies on various Lewis pairs as a function of geometric and energetic properties of the functional moieties.