A bio-metal-organic framework for highly selective CO2 capture: A molecular simulation study

Abstract

A recently synthesized bio-metal-organic framework (bio-MOF-11) is investigated for CO2 capture by molecular simulation. The adenine biomolecular linkers in bio-MOF-11 contain Lewis basic amino and pyrimidine groups as the preferential adsorption sites. The simulated and experimental adsorption isotherms of pure CO2, H2, and N2 are in perfect agreement. Bio-MOF-11 exhibits larger adsorption capacities compared to numerous zeolites, activated carbons, and MOFs, which is attributed to the presence of multiple Lewis basic sites and nano-sized channels. The results for the adsorption of CO2/H2 and CO2/N2 mixtures in bio-MOF-11 show that CO2 is more dominantly adsorbed than H2 and N2. With increasing pressure, the selectivity of CO2/H2 initially increases owing to the strong interactions between CO2 and the framework, and then decreases as a consequence of the entropy effect. However, the selectivity of CO2/N2 monotonically increases with increasing pressure and finally reaches a constant. The selectivities in bio-MOF-11 are higher than in many nanoporous materials. The simulation results also reveal that a small amount of H2O has a negligible effect on the separation of CO2/H2 and CO2/N2 mixtures. The simulation study provides quantitative microscopic insight into the adsorption mechanism in bio-MOF-11 and suggests that bio-MOF-11 may be interesting for pre- and post-combustion CO2 capture. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.