Preparation, Characterization And Catalytic Properties Of SO₄^2-/SnO₂Load Solid Acid

Preparation, characterization and catalytic properties of SO₄^2-/SnO₂-SiO₂、SO₄^2-/SnO₂-MCM-41. Silica gel was synthesized by mixing sodium silicate and ammonium nitrate, and tin （IV）hydroxide was synthesized by mixing stannic chloride and ammonia water. SnO₂-SiO₂wasprepared by direct method，then it was dipped with the different concentration H₂SO₄. Thesynthesis conditions were optimized by single factor experiments. The best conditions wasthat n（Sn）：n（Si）=0.3, dipping concentration was0.5mol/L and calcinations temperature was400℃. The catalysts are characterized by XRD, FT-IR, N2adsorption-desorption, TG/DTA,SEM and so on.Characterization results show that SO₄^2-/SnO₂-SiO₂don’t have a pore structure; particlesize distribution is more uniform. SnO₂-MCM-41catalyst was synthesized withhexadecyltrimethylammonium bromide （CTAB） as template and tetraethyl orthosilicate（TEOS） as silicon source by direct synthesis. SnO₂-MCM-41was dipped with differentconcentration H₂SO₄. The synthesis conditions were optimized by single factor experiments.The best synthesis conditions was that n（Sn）：n（Si）=0.1, dipping concentration was0.5mol/Land calcinations temperature was300℃.Charaction results show that SO₄^2-/SnO₂-MCM-41have pore structure and pore distributed uniformity, which is the typical mesoporousstructure.Laurie acid methyl ester was synthesized over the catalysts synthesized. The main effectson esterification such as the ratio of acid to alcohol, the amount of catalyst and reaction timehave been discussed. The results indicated that reaction time was4.0h, n[CH3（CH2）10COOH]:n（CH3OH）=1:10, the amount of the catalyst of SO₄^2-/SnO₂-SiO₂was0.25g. The conversionrate of Lauric acid was80.54%under the reaction condition. Catalytic performance ofSO₄^2-/SnO₂-MCM-41was investigated by synthesizing lauric acid methyl ester. The resultsindicated that reaction time was6.0h, n[CH3（CH2）10COOH]: n（CH3OH）=1:12,the amountof catalyst was0.25g. The conversion rate of Lauric acid was92.34%under the reactioncondition. Experiments show that the kinds of solid acid catalysts have good catalyticproperties.