Synthesis And Glucose Oxidase Catalytic Properties Of Mesoporous Silica/Palladium Nanoparticles

As the deep-processed products of glucose, gluconate have a wide range of applications in chemical industry, food, medicine, light industry, etc. The major problems such as high temperature requirements, long acting cycle, multi-products, low purity of products are found in the traditional process of preparing gluconic acid. Nowdays, researchers focuse on the supported metal catalysts which is one of the heterogeneous catalysis. And Pd has high activity for glucose oxidation. Mesoporous materials, as the support of metal nanoparticle, has high surface area and stability, but the calcination during its preparation easily lead to pore collapse. In this thesis, supported palladium catalysts prepared by a simple and gentle method were used in the oxidation of glucose.MSN was prepared by the sol-gel method with N-cetyltrimethyl-ammonium bromide(CTAB) as the template, and then Pd/MSN was synthesised using palladium choride as metal source and sodium borohydride as reducing agent. The structure of Pd/MSN was characterized by FI-IR, XRD, SEM, TEM and BET. Results show that good orderliness mesoporous structures are remantained in Pd/MSN nano-particles, MSN and Pd/MSN nano-particles have good dispersibility and stable shape.A catalytic activity of 95.6% was obtained using Pd/MSN catalyst under the optimal preparation condition in glucose oxidation. The shape and size of support were affected by concentration of template(CTAB), species and concentration of alkali. MSN prepared under different concentration of CTAB, species and concentration of alkal, which was characterized, supporting Pd nanoparticles to catalysis the oxidation of glucose. The catalytic activity of the final catalyst as well as the shape of mesoporous silica were affected by these factors. It obtained a higher catalytic activity with Na OH(14 m M) and CTAB(5.7 m M).The catalytic activity of the catalyst was greatly influenced by preparation conditions, such as impregnation methods, species and amount of reducing agent, protective agent. These factors were investigated and we found that the catalytic activity of Pd/MSN prepared by ultrasonic immersion was better than raditional chemical immersion, Na BH4 as reductant was better than other reductants.During the process of glucose oxidation, condition of the reaction such as loadings of palladium, temperature and stirring rate on catalytic activity were studied. The glucose was optimized by the Box- Behnken model for response surface optimization, results indicated that the optimal condition of the reaction was as follows: 4.2% palladium loading, stirring rate 500 r/min, reaction temperature at 80 oC.