Improved silica–titania catalysts by chitin biotemplating
Silica–titania materials with improved catalytic performance were elaborated as mesoporous microparticles by combining sol–gel and spray-drying processes with the self-assembly properties of α-chitin nanorods acting as biotemplates. Three different synthesis approaches are discussed, leading to materials with varied textural and chemical characteristics studied by SEM, N2 volumetry, TEM, XPS and DR-UV techniques. The use of water or ethanol as initial solvent for chitin nanorod suspensions, as well as the mixing conditions of the precursors, has been shown to have a significant impact on the final properties. Materials of specific surface areas of up to 590 m2 g−1 and porous volumes of up to 0.84 mL g−1, with low surface Si/Ti ratio, could be disclosed. Properties were further investigated by employing the silica–titania materials as heterogeneous catalysts for the sulfoxidation of bulky model compounds. The location of Ti active sites at the pore surface has been maximized and allows for improved productivity.