Theoretical Screening Good Sorbents for CO2 Separation

Carbon dioxide is the major product from coal combustion and is released into the air and causes global climate warming which we are facing today. Current technologies for capturing CO2 including solvent-based (amines) and CaO-based materials are still too energy intensive. Hence, there is critical need for new materials that can capture and release CO2 reversibly with acceptable energy costs. Accordingly, solid sorbent materials have been proposed for capturing CO2 through a reversible chemical transformation and most of them result in the formation of carbonate products. By combining first principles density functional theory and phonon lattice dynamics calculations, the thermodynamic properties of solid materials are obtained and used for computing the thermodynamic reaction equilibrium properties of CO2 absorption/desorption cycle based on the chemical potential and heat of reaction analysis. According to the pre- and post- combustion technology and conditions (such as CO2 partial pressures and temperatures) in power-plants, based on our calculated thermodynamic properties of reactions for each solid capturing CO2 varying with temperatures and pressures, only those solid materials, which result lower energy cost in the capture and regeneration process and could work at desired conditions of CO2 pressure and temperature, will be selected as promised candidates of CO2 sorbents and further be sent for experimental validations. By combining ab initio calculations with molecular dynamics or Monte Carlo simulations, the CO2 capture behavior of solutions (such as amino acids, peptides, salts, etc.) also can be evaluated. The results can provide some guidelines for improving amine-based CO2 capture technology. Here in this talk, we first present our screening methodology and report our results on alkali and alkaline earth metal oxides, hydroxides and carbonates/bicarbonates and compare with available thermodynamic data. Then, we apply our methodology to predict good candidates of CO2. sorbents from vast of mixing and substituted/doped solids which thermodynamic data are usually not available.[1-3] Lastly, we will present some preliminary results on arginine amino acid capturing CO2 by comparing with MEA.