Mesoporous titania–silica composite from sodium silicate and titanium oxychloride. Part II: one-pot co-condensation method

摘要

Mesoporous titania–silica composite with large primary particles and homogeneous dispersion of Ti in the silica matrix were synthesized by the sol–gel method via a one-pot co-condensation method using cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. Freshly prepared titanium oxychloride (TiOCl₂, titania precursor that is relatively stable) and sodium silicate were used as titania and silica precursors (at the initial ratio of Ti:Si = 1), respectively. The final products were obtained after removing the template by calcination and had overall ratio of Ti:Si = 2:3 (based on EDS and XRF analyses). Other characterization techniques employed include FE-SEM, TEM, FT-IR, DTGA, and nitrogen physisorption studies. The textural properties of the products were highly influenced by the molar concentration of CTAB. Materials with large primary particles (submicrometer-scale dimensions) were obtained at higher concentrations of CTAB (1.7 wt%). The porosities of the templated material were highly reduced compared to that of the untemplated material, emphasizing the influence of Ti loading in the silica matrix. Both pore size and surface area increased at a calcination temperature of 550 °C. The DTGA result showed that the composites exhibited elevated thermal stability (up to 900 °C). In summary, mesoporous titania–silica composite with desirable properties were developed via the proposed method using a relatively inexpensive silica precursor.