Title: Preparation of Solid Acid SO~(2-)_4/SiO_2-TiO_2 and Its Catalytic Activity for Esterification
Abstract: Solid acid catalysts SO~ 2- _4/SiO_2-TiO_2 with different SiO_2/TiO_2 ratios and calcined at different temperatures were prepared by mechanical mixing and impregnation methods. The catalysts were used for esterification of ethanol and acetic acid. SO~ 2- _4/40%SiO_2-TiO_2 prepared by mechanical mixing and calcination at 400 ℃ exhibited the highest activity, and the acetic acid conversion was nearly 100% in partial reflux rectifying esterification and up to 84% in total reflux esterification, which was close to the chemical equilibrium composition. X-ray diffraction patterns indicated that SiO_2 inhibited the excessive formation of titanium oxide sulfate. The combination of tetragonal crystal anatase TiO_2, orthorhombic crystal titanium oxide sulfate, and cubic crystal titanium with high surface area SiO_2 ensured the high activity of the catalysts. Infrared spectra showed that the addition of SiO_2 helped the formation of Ti-O-Si linkage which enhanced the strong bonding of SO~ 2- _4 with the catalyst surface. The sulfate species bonded were in bidentately chelating and covalent sulfate structures. Thermogravimetric-differential scanning calorimetry proved that SO~ 2- _4 was hardly removed with the addition of SiO_2 and the temperature for transformation of anatase to rutile was lowered.
Publication Year: 2006
Publication Date: 2006-01-01
Language: en
Type: article
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Cited By Count: 5
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