科研之友
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摘要
Sulfated titania loaded mesoporous silica solid acid catalyst was successfully obtained by a facile ammonia/water vapor-induced internal hydrolysis route. Ti(SO4)(2) used as titania precursor and the supplier of SO4 (2-) ions. By controlling the hydrolysis rate of precursor under ammonia/water vapor ambience, a thin titania layer formed and coated on the pore internal surface of SBA-15. The solid acid catalyst was characterized by powder X-ray diffraction, N-2 adsorption-desorption and transmission electron microscopy, and the results showed that such catalyst retained the ordered mesoporous structure, relatively high surface area, connected and open pore channel without pore blocking. Fourier transform infrared spectroscopy and energy dispersive spectrum analysis results indicated that the resultant catalyst possessed higher connect of sulfate groups and more catalytically active sites than those of unloaded sulfated titania and sulfated titania loaded SBA-15 hydrolyzed by ammonia aqueous solution. Meanwhile, the catalyzing results suggested such solid acid catalyst exhibited improved catalytic property for esterification of oleic acid with methanol compared to conventional sulfated titania solid acid. In addition, the experimental parameters including reaction time, reaction temperature and the molar ratio of reactants were optimized, and ca. 85 % of catalytic activity were remained after three consecutive cycles.
