Theoretical Investigation for Adsorption of CO2 and CO on MIL-101 Compounds with Unsaturated Metal Sites

In present study, the adsorption of CO2 and CO on the metal-organic framework chromium (III) terephthalate (MIL-101) were investigated using generalized gradient approximation with DFT-D correction. Non-covalent interaction analyses (NCI) were also performed to further investigate the interaction between MIL-101 and gas molecules. The theoretical results indicated that the preferential adsorption mode of CO2 on MIL-101 is different with that of CO. The preferential adsorption mode of CO2 on MIL-101 involves one oxygen atom of CO2 (O-CO2) coordinating with exposed Cr atoms through dominated Lewis acid-base interaction. The calculation results indicate that the transference from C-CO to the exposed Cr atom causes the CO adsorption ability of MIL-101 to be much stronger than its corresponding CO2 adsorption ability. The theoretical investigation reveals the nature and strength of CO2 and CO adsorptions on MIL-101 and facilitates the development of new MOFs with high CO2 or CO adsorption capacity and selectivity. (C) 2014 Elsevier B.V. All rights reserved.