Preparation And Modification And Evaluation Of SO₄～(2-)/TiO₂ Solid Superacid

As the terrible pollution problem existing in the synthesis of ethyl oleate , the solid superacid catalyst SO42-/TiO2 was prepared and studied. Compared with the traditional catalyst H2SO4, the solid superacid catalyst has a lot of advantages, such as higher catalytic activity, lower cost in the preparation, no corrosion to equipments and preventing acid wastewater from draining off etc. Apart from that using solid superacid catalysts, organic synthesis technology craft has the characters of green chemistry and cleaning production. So they have high academic value and widely applied prospect.In this paper, SO42-/TiO2 was prepared and processed a series of modification. Then the catalysts were used in the esterification of oleic acid and ethanol. The result showed that the solid superacid behaved well in the esterification.First, the preparation method of the catalyst SO42-/TiO2 was made sure by experiment. The preparing conditions were optimized and discussed according to different yields through which the activity of the catalyst in esterification of propanoic acid and n-butyl alcohol was measured. The best preparing conditions were as following: pH=8, the depositing time equal to 24h, the concentration of H2SO4 equal to 1.25mol/L, the impregnated time equal to 16h, and the burning temperature equal to 500℃.Second, the solid superacid SO42-/TiO2 was modified. SO42-/TiO2/La3+ showed the best activity in esterification. Its preparing conditions were optimized. The best preparing conditions were as following: pH=8, the depositing time equal to 24h, the concentration of H2SO4 equal to 1.25mol/L, the concentration of La(NO3)3 equal to 5% in the H2SO4 solution, the impregnated time equal to 16h, and the burning temperature equal to 500℃.Third, the solid superacids were analyzed and characterized by XRD, FT-IR, TG/DSC and TPD. The relationships between properties and structures were also investigated. In the TPD curves, we can conclude that the acidity of SO42-/TiO2/La3+ is better than SO42-/TiO2. By the IR analyzed, we found that SO42- is combined with metal ions of TiO2 in a chelating bidentate mode. By XRD...