Immobilization of ionic liquids within micro- and mesoporous materials

Room temperature imidazolium-based ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) was immobilized within high-silica zeolite Beta and mesoporous silica (SBA-15) samples using methanol as solvent. The resultant samples were then subjected to Soxhlet extraction in order to remove the ionic liquids which are loosely bound on the external surfaces. All the samples (before and after Soxhlet extraction) were analyzed by TG-DTA, 13C MAS-NMR and N2-adsorption measurements. Upon immobilization of ionic liquid, the BET surface areas of the host materials decreased significantly. Nevertheless, the ionic liquid immobilized host materials regained their surface areas after Soxhlet extraction. The amount of immobilized ionic liquid was estimated from TG measurements to be 0.6 wt.% (zeolite Beta) and 1.3 wt.% (SBA-15), respectively.