Imidazolium-based ionic liquid silica xerogel as catalyst to transform CO2 into cyclic carbonate

Abstract

In this work silica xerogel samples containing different imidazolium ILs (EMIM-CF3SO3, EMIM-MSO3, BMIM-Cl, MBMIM-TF2N, BMIM-TF2N and EMIM-TF2N) were synthesized, characterized and used as catalyst in cyclic carbonate synthesis. ILs mass percentage was varied from 5% to 25%. The effect fostered by the ILs mass variation in the synthesis of silica xerogel was observed both in the materials characterization as well as in the performance of these materials as solid catalysts in the cyclic carbonate synthesis from the cycloaddition reaction of CO2 with propylene epoxide. The obtained silica xerogel samples (SXs) were characterized by FTIR, RAMAN, TGA, SEM and TEM. The selectivity of the cycloaddition reaction was analyzed by GC and 1H and 13C NMR. The best results were obtained for SX-EMIM MSO3 (20% of IL) and SX-BMIM Cl (15% of IL) with propylene carbonate yields of 91.4% and 83.4% and selectivities >99% and 97.4% respectively.