Synthesis, characterization and catalytic activity of ordered macroporous silicas functionalized with organosulfur groups

Hybrid three-dimensionally ordered macroporous (3DOM) SiO{sub 2}-SO{sub 3}H materials with different S/Si ratio have been prepared by colloidal crystal templating method. The process involved preparation of 3DOM SiO{sub 2}-SH materials by co-condensation of (3-mercaptopropyl)triethoxysilane and tetraethoxysilane via sol-gel transformation, and following oxidation of -SH group to -SO{sub 3}H group by H{sub 2}O{sub 2}. Materials were characterized by scanning electron microscopy (SEM), Fourier transform infra-red spectrometer (FTIR), thermogravimetric analysis (TGA), and nitrogen adsorption measurement. SEM observation shows that the macropores are highly ordered with a typical 'surface-templated' structure. The surface area of 3DOM SiO{sub 2}-SH material is 25.1 m{sup 2}/g and SiO{sub 2}-SO{sub 3}H material is 18.6 m{sup 2}/g. Catalytic activity test shows that 3DOM SiO{sub 2}-SO{sub 3}H materials possess a high activity for the esterification of acetic acid and n-butanol, and the activity is increased with the amount of sulfur in the materials. This study provided significant results for developing new application of 3DOM materials.