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A sulfated titania–silica composite (S-TSC) was obtained through surface modification of mesoporous
titania–silica composite synthesized using less expensive precursors; titanium oxychloride and sodium
silicate as titania and silica sources respectively. A pre-formed titania sol facilitated the synthesis of a
mesoporous composite with a high BET surface area (520 m2/g), suitable for surface modification using
sulfuric acid to improve its catalytic performance. The materials synthesized via this process were examined
by XRD, XRF, FTIR, SEM, TEM, TGA, and N2 physisorption studies. FTIR analysis showed the vibration
band of the TiAOASi bond at 943 cm 1, suggesting the incorporation of titania into silica to form a composite.
This vibration band was substantially shifted to 952 cm 1 after the attachment of the sulfate
group. The catalytic activity of a series of as-prepared TSC, S-TSC calcined samples and pure H2SO4 were
evaluated for esterification of oleic acid and transesterification of waste oil with methanol to yield methyl
esters. It was observed that at these reaction conditions, S-TSC-450 and S-TSC-550 possessed high catalytic
activity comparable to that of pure H2SO4 implying that surface modification of the titania–silica
composite improves its acidic properties. |
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