Preparation Of Solid Acid Catalyst For Synthesis Of Non-toxic Plasticizer

Along with the development of modern industry, the production of Nontoxic Plasticizer becomes more and more important. The production of Plasticizer is mainly depend on the esterification, at the same time,need the catalytic of catalyst. Some homogeneous catalyst are used as the traditional catalysts to synthesize esters, in order to comply with the principles of green chemistry and reduce the economic costs, now the science research mainly concentrated on the solid acid catalysts.The Mesoporous silica have broad prospect of application in different research fields attribute to its peculiar advantages, such as high specific surface area, large pore diameter and pore volume, the uniform distribution of pore size, the periodically ordered pores, more hydroxyl on the surface so that chemical modification. There are many ways to modified mesoporous silica:Metal modified, Loaded active components and modified by Silane coupling agent.In this article, four solid acid catalyst were prepared, catalytic properties and recyclability were tested for synthesis of trioctyl citrate or trioctyl trimellitate.Mainly included following four parts:1. Mesoporous molecular sieve KIT-6 was prepared by hydrothermal synthetic method. The sulfonic solid acid was obtained by KIT-6 functionalized with 3-mercaptopropyl trimethoxysilane and Subsequently by H2O2 oxidation. The structure and morphology of catalyst were characterized by means of Fourier Transform Infrared spectroscopy?FT-IR?, N2 adsorption-desorption isotherms?BET?, X-ray diffraction?XRD?, transmission electron micrographs?TEM?, Thermal analysis?TGA? and elemental analysis?EA?. Trioctyl citrate was synthesized with citric acid and isooctyl alcohol to examine the activity of the catalyst by orthogonal experiments designning.The results showed that the primary and secondary relations of the factors in this experiment and the optimum reaction conditions. The esterification yield could reach 91.2% under the optimum reaction conditions:alcohol/acid molar ratio was 5,catalyst/acid mass ratio 3%,reaction temperature was 160 °C and reaction time was 2.5 h. At the same time, the catalyst can be used for many times with a good stability.2. Mesoporous molecular sieve MCM-41 are prepared by hydrothermal crystalization method using tetraethyl orthosilicate?TEOS? as silicon source and cetyltrimethylammonium bromide?CTAB? as structural template under the alkaline condition. The Supported solid acid catalyst p-TSA/MCM-41 was first prepared by an impregnation method and characterized by Fourier Transform Infrared spectroscopy?FT-IR?, X-ray diffraction?XRD?, N2 adsorption-desorption isotherms?BET?, Thermal analysis?TGA?, transmission electron micrographs?TEM? and elemental analysis?EA? technique. Taken it as a catalyst to synthesis of trioctyl citrate and effects of reaction temperature, molar ratio of citric acid to isooctyl alcohol, amount of catalyst and reaction time on the esterification were investigated by using single factor experiment. The esterification yield could reach 96.7% under the optimum reaction conditions: the reaction temperature was 160 °C, the molar ratio of citrate acid to isooctyl alcohol was 1:5, the weight of catalyst was 3% of citric acid weight and the reaction time was 2.5 h. At the same time, the esterification yield was still kept 80.5% when the catalyst could be repeatedly used 5 times. Therefore, it is a good catalyst for the synthesis of trioctyl citrate.3. A novel solid acid catalyst, hydrophobic bifunctional mesoporous of KIT-6 was prepared by KIT-6 functionalized with 3-mercaptopropyl trimethoxysilane and ndodecyltrimethoxysilane by a post-synthesis grafting approach and then by H2O2 oxidation. The samples were characterized by Fourier Transform Infrared spectroscopy?FT-IR?, elemental analysis?EA?, X-ray diffraction?XRD?, N2 adsorption-desorption isotherms?BET?, transmission electron micrographs?TEM? and Thermal analysis?TGA? measurements. The catalytic activity of catalyst was tested for the esterification of trimellitic anhydride with 2-ethyl hexanol. The orthogonal experiments results show that the esterification yield was 97.4% under the the optimum reaction conditions: the reaction temperature was 210 °C, the molar ratio of trimellitic anhydride to 2-ethylhexyl alcohol was 1:4, the dosage of catalyst was 5% of trimellitic anhydride weight and the reaction time was 5 h. At the same time, the catalyst can be easily seperated and with a good recyclability.4. The solid acid catalyst 300-Nb₂O₅/PG was obtained by the procedure of Niobium ion-exchanged Palygorskite and calcination. The catalyst was characterized by analytical techniques such as Fourier Transform Infrared spectroscopy?FT-IR?, Xray diffraction?XRD?, N2 adsorption-desorption isotherms?BET?, Scanning Electron Microscope?SEM?, Diffuse reflectance spectroscopy?DRS?, Thermal analysis?TGA?, X-ray photoelectron spectroscopy?XPS?. The catalytic activity of solid acid was tested for the esterification of Trioctyl trimellitate?TOTM? from trimellitic anhydride with 2-ethyl hexanol. The effects of reaction temperature, molar ratio of trimellitic anhydride to 2-ethyl hexanol, amount of catalyst and reaction time on the esterification were investigated by using single factor experiment. The experimental results indicated that the esterification yield could reach 95.3% under the optimum reaction conditions: the reaction temperature was 210 °C, the molar ratio of 2-ethyl hexanol to trimellitic anhydride was 4:1, the weight of catalyst was 3% of trimellitic anhydride weight and the reaction time was 5 h. Under this conditions, the catalyst could be repeatedly used 5 times without any further treatments, with the yield still kept over 89%.