Preparation And Catalytic Properties Of Supported Solid Superacid Catalysts

Solid acid catalyst is used in a variety of chemical reactions due to its high selectivity, activity, and its highly repeated usage. As green catalytic materials, solid acid catalyst is concerned highly. Traditional liquid acid catalyst, such as H2SO4, HF, HNO3, is easy to rust equipment and is difficult recycling, and would cause serious pollution to environment, which is contrary to our concept of "green chemistry". So we must improve chemical processes, and we should use high efficiency and small pollution catalyst.Compared to conventional liquid acid catalyst, solid acid catalyst has a lot of advantages such as non-toxic, non-corrosive and reused, no pollution. And solid acid catalyst also has characteristics such as high activity and selectivity, easy separation with the reactants, less side effects, and high rate of reusing. Thus it replaces the traditional liquid acid,and it is widely used as chemical catalysts. Then it develops rapidly.The paper has prepared a series of solid super acid catalyst. SO42-/ZrO2, SO42-/ ZrO2-La2O3 solid acid and ZrOCl2/HAP were prepared by impregnation method. The structure of the prepared catalyst was characterized by XRD, TEM. The acid content of catalyst was determined using titration method. The catalytic activity was investigated using esterification reaction of n-butanol and citric acid as model.Here is the main contents in the paper:(ⅰ) SO42-/ZrO2 solid acid was prepared using the impregnation method.The better preparation conditions was that the samples were calcined for 3h under 600 ℃. The better esterification reaction condition in the reaction of n-butanol and citric acid was as follows:the molar ratio of n-butanol and citric acid was 4.5, the amount of catalyst SO42-/ZrO2 was 1.5% to citric acid, the reaction time was 4h, esterification rate was 87.5%. After the sample was reused five times, esterification was 84.3%.(ⅱ) SO42-/ZrO2-La2O3 super solid acid was prepared using the impregnation method.The better preparation conditions was that the samples was calcined for 3h under 600 ℃,the rare earth elements La doping amount was 4%. The better esterification reaction condition in the reaction of n-butanol and citric acid was as follows:the molar ratio of n-butanol and citric acid was 4.5, the amount of catalyst SO42-/ZrO2 was 1.5% to citric acid, the reaction time was 4h, esterification rate was up to 97.26%. After the sample was reused five times, esterification was 95.47%. The possible mechanism of acid center of SO42-/ZrO2-La2O3 super solid acid was discussed in the paper.(ⅲ) HAP and ZrOCl2/HAP was prepared using the hydrothermal and impregnation method. The better doping content of ZrOCl2 was 40mmol/L. The esterification rate was up to 97.22% in the esterification reaction of n-butanol and citric acid. After the sample was reused five times, esterification was 85.50%.