Synthesis Of Mesoporous Materials With An Ionic Liquid-assisted Sol-gel Method

Based on their regularly periodic pore structures, highly uniform and relatively large pore size?2-50 nm?, large pore volume, high surface area and adjustable pore stuctures, mesoporous materials have tremendous applications in catalysis, adsorption-separation, biopharmaceutical synthesis and so on.Ionic liquids?ILs? have been widely used in the field of materials synthesis due to their low interfacial tension, thermal stability, wide liquid range, amphipathic nature and superamolecular structure formed based on hydrogen bonds.In this paper, imidazolium-based ionic liquids have been used as templates to synthesize mesoporous silicas and mesoporeous aluminas with different morphologies and mesostructures. Moreover, the mechanism of synthesis of mesoporous materials with ionic liquids was studied in depth.Mesoporous mesoporous silica was synthesized via sol-gel process with ionic liquids as templates, tetraethyl orthosilicate?TEOS? as the precursor and hydrochloric acid?HCl? as the catalyst. The effects of the type and amount of the template on the mesostructures and mophologies of silica were mainly studied. The results show that, for the mesostructrue controllability, worm-like mesoporous silicas have been synthesized templated by [Bmim]Tfo, [Bmim]Cl and [Bmim]PF₆ respectively; highly ordered bimodal mesoporous silicas have been prepared with P123 and ionic liquid?[Bmim]Tfo, [Bmim]Cl or [Bmim]PF₆? as co-template; For the morphologycontrollable synthesis, silica hollow spheres were obtained templated only by [Dmim]Cl andsilica tubes with highly ordered mesoporous walls have been successfully synthesized with P123 and [Dmim]Cl as co-template.For the synthesis of mesoporous alumina, an ionic liquid-assisted sol-gel method with aluminium isopropoxide as the precursor was also developed. The influences of different media, the type and amount of the template and calcination temperature on the mesostructure and mophologies of alumina were mainly investigated. The results suggest that: in water medium, ordered mesoporous alumina was successfully synthesized templated by [Bmim]PF₆; in ethanol media, rod-like mesoporous alumina could be successfully obtained with different ionic liquid?[Bmim]PF₆, [Bmim]Tfo, [Bmim]Cl, [Dmim]Cl or [C16mim]Cl? as the template and the amount of the ionic liquid played key role in controlling the morphology of alumuna.Furthermore, the mechanisms of synthesis of materials induced by ionic liquids or ILs-surfactants cotemplate were in depth disclosed, which will have theoretical guiding significance in morphology and mesostructure-controllable synthesis of mesoporous materials.