Rationalizing the role of the anion in CO2 capture and conversion using imidazolium-based ionic liquid modified mesoporous silicaElectronic supplementary information (ESI) available: FTIR absorption bands of IL and supported IL, TGA thermogram of sample ILTf2NM50 and N2 adsorption-desorption isotherms at 77 K on different samples. See DOI: 10.1039/c5ra07561k

Covalently supported ionic liquids in mesoporous materials were prepared by grafting 1-methyl-3-(3-trimethoxysylilpropyl)imidazolium chloride in MCM-41. Subsequently, the [Cl − ] anion was changed to [BF 4 − ], [PF 6 − ] or [Tf 2 N − ]. These materials that present an advantageous combination of the properties of mesoporous solid materials and ionic liquids were evaluated for CO 2 sorption as well as catalysts for CO 2 conversion into cyclic carbonate using propylene oxide. The material with the [Cl − ] anion had the best performance for both CO 2 sorption and conversion. A CO 2 sorption of 11 w/w% on the adsorbent was achieved and the cycloaddition reaction exhibited a conversion of 67% with 82% selectivity with the catalyst remaining active after 5 cycles, proving that the same sorbent/catalyst setup can be used for both CO 2 capture and conversion. Based on the experimental data and electronic-structure numerical simulations, we have hypothesized two major reasons why chloride out performs other anions when adsorbed on MCM-41 unlike unsupported ionic liquids. Covalently supported ionic liquids in mesoporous materials were prepared by grafting 1-methyl-3-(3-trimethoxysylilpropyl)imidazolium chloride in MCM-41.