Study On Synthesis And Catalytic Performances Of Clay-Based Redox Composites

Using natural minerals as starting layered host, two kinds of porous clay-based composites were synthesized by in situ self-assemble of sol particles in the interlayers, and it could decrease the cost of catalysts and increase the properties in the phenol hydroxylation. One was iron pillared montmorillonites prepared by the reaction of Na⁺-montmorillonite with base-hydrolyzed solutions of Fe³⁺ salts and then calcined at high temperature. Several synthesis conditions were studied, such as the anion of cross-linking agent, the ratio of [CO₃^2-]/[Fe³⁺], the aging time of the cross-linking agent and the doping of alumina and so on; The other was TS-1/montmorillonite (TSM), which was a new kind of micropore and mesopore composite, and the influence of crystallization temperature, crystallization time, content of TPAOH, TBOT and TEOS were studied. Then the structure and surface properties of synthetic clay-based composite materials were characterized by using modern physical and chemical techniques such as X-ray diffraction (XRD), fourier transformation infra-red spectra (FT-IR), ultra violet-visible spectra (UV-Vis), nitrogenadsorption-desorption isotherms and scanning electron micrograph (SEM). Finally the catalytic properties of synthesized composites as catalysts in phenol hydroxylation with H2O2 to dihydroxybenzenes were investigated.By studying on the synthesis conditions of Fe-PILC, results showed that montmorillonite was successfully pillared at [CO32"]/[Fe3+] <1.5, the layered structure of montmorillonite was destroyed at [CO32']/[Fe3+] ^ 1.5. The aging time of the cross-linking agent was 24 hours. The N2 adsorption-desorption isotherms of Fe-PILC and Al-doped Fe-PILC was type IV, and BET surface area and a sharp and single pore size distribution of Fe-PILC were 103.97 m2/g and 17.92 A. To Al-doped Fe-PILC, the extent of ordered pillaring was relatively higher at Fe/Fe+Al = 0.05, and BET surface area and a sharp and single pore size distribution were 111.59 m2/g and 19.15 A. Thermal stability of Al-doped PILC was improved.By studying on the synthesis conditions of TSM, results showed that crystallization temperature was 175 °C, crystallization time was 5 days. As hydrolyzing TBOT and TEOS at room temperature in lg of NH1"- montmorillonite, the compositional molar relations was as following: 12 TPAOH: 1 TiO2: 13 SiO2: 404 H2O: 100 EtOH; While hydrolyzing at 60°C in lg of NH^-montmorillonite, the compositional molar relations was as following: 9 TPAOH: 1 TiO2: 18 SiO2: 404 H2O: 100 EtOH. According to the N2 adsorption-desorption isotherms there were two kinds of mesopore structures on TSM. In SEM images it could be found that the TS-1 was...