Synthesis Of Novel Inorganic Catalytic Materials And Exploration Of Their Catalytic Properties

The environmental problems, such as greenhouse effect, air pollution, water pollution, have atractted more and more attention. In recent years, the developed countries cope with the environmental problems from passively handling problems to exploring new production process and technology, reduce the origin of pollution and manufacture environmental-friendly production. The green technology is considered the hot matter and important technological forntier of chemical engineering technique and chemical research. In the chemical industry, huge amount of solvents are used in the reaction, separation and other procedures, which are volatile, incendive or harmful organic materials. These solvents are one of the sources of pollution. In order to reduce the application of the volatile organic solvents, scientists have proposed many solutions, such as using non-solvent synthesis, water and supercritical solvent and ion-liquid solvent instead of volatile organic solvents.Supercritical fluids are the fluids whose temperature and pressure are above their critical points. This kind of fluid has unique properties, good dissolution ability for non-volatile materials, zero surface tension, great diffusion coefficient and their physical and chemical qualities are sensitive to the small changes of temperature and pressure. Therefore, these properties can be changed by adjusting the temperature and pressure, especially near the critical points. Llittle changes in temperature or pressure can cause great changs in the properties of the fluids, such as density, diffusion coefficient and dissolution ability for solvent.It is well known that mesoporous matetials are widely used in the catalytical fields because of their lare surface area. Compared with the micropore, lare pores have many advantages, favoring the diffusion of reacts and products, can catalyze the reaction of lare molecular and so on.Supercritical carbon dioxide has been used in the porous materials synthesis such as porous polymer, organic small molecular porous materials, inorganic porous materials and so on. The environmental friendly supercritical fluids not only replace the harmfull organic solvents, but also synthesis some special materials, which can not be synthesized by other methods.Zeolites have been widely applied in industrial catalysis, but their relatively small and sole micropores strongly influence the mass transfer of reactants and products and catalytic conversion of bulky molecules, and one solution for this problem is to prepare mesoporous zeolites. In this work, we demonstrate a"greener"super-critical CO2 route for the fast synthesis of mesoporous silicalite-I. Differing from the conventional synthesis, supercritical CO2 route for the formation of mesoporosity is template-free, and it takes very short time for crystallization of silicalite-I zeolite (4-8h). Very importantly, the catalytic tests in Beckmann rearrangement of cyclohexanone oxime intoε-caprolactam (CPL), the monomer of nylon-6, shows that mesoporous silicalite-I is more active and stable than conventional silicalite-I. In the synthesis of Y and Beta zeolites in scCO2, the crystallization time are also shortened because the carbonate species, which are formed from hydration of CO2 in scCO2, act as efficient promoters for the enhancement of the crystallization rate of xilicate zeolites.Meanwhile, in the crystallization process of Beta, scCO2 also helps to synthesis mesoporous Beta.At last, benzyl alcohol oxidation using oxygen as green oxidant is carried out in supercritical CO2 over Pd-Pt/CNF catalyst. Various reaction parameters such as reaction temperatures, O2 and CO2 pressures, pretreatment conditions of catalyst, and support have been investigated in detail.