The Design And Preparation Of Different Catalysts Based On Graphene Oxide For Catalytic Oxidative Reaction

Because of easy separation and recycle, heterogeneous catalysts have attracted much attention in industrial application. However, practical applications of the heterogeneous catalysts are often limited by their lower catalytically active as compared with homogeneous ones. To solve the problem, graphene oxide(GO) has been employed as the support for developing novel “pseudo homogeneous” heterogeneous catalysts. The unique layered structure, large specific surface area, and abundant surface oxygenated functional groups of GO made these heterogeneous catalysts highly efficient and reusable in corresponding oxidations.1. The amino(-NH2) group modified GO(GO-NH2) was used as support for gold nanoparticle. First, HAuCl4, the precursor of gold nanoparticle, was anchored to GO by acid-base reaction between HAuCl4 and amino group. Ethanediol was then used as the reductant to reduce the anchored AuCl4- ion to Au0 nanoparticle. Uniform Au0 nanoparticle was thus captured by amino group on the surface of GO. The obtained catalyst(Au/GO-NH2) was characterized by XRD, TEM, XPS and FT-IR. The catalytic performance of the catalysts was evaluated by epoxidation reaction of various olefins with H2O2.2. A novel Mn2+/GO nanocomposite has been developed by coordination of the Mn2+ions of Mn(OAc)2·4H2O with the oxygenated functional groups of the GO sheets. The obtained Mn2+/GO catalyst was characterized by XRD, XPS, FT-IR, UV-vis and Zeta potential analysis. The catalytic properties of Mn2+/GO catalysts were evaluated by epoxidation reaction of various olefins with H2O2.3. Imidazolium-based ionic liquid(IL)-functionalized GO was prepared and used to support chiral salen Mn(III) complex through covalent linkage. Technologies of characterization suggested that intact chiral complex was covalently appended on flat planes and edge of GO sheet through an imidazolium-based IL linker. The obtained catalyst(GO-IL-salen Mn(III)) was characterized by XRD, XPS, FT-IR, and UV-vis. The catalytic performance of GO-IL-salen Mn(III) catalysts was evaluated in enantioselective epoxidation of unfunctionalized olefins in CH2Cl2 using NaClO as an oxidant.4. An amine-terminated IL(IL-NH2) functionalized GO(GO-NH-IL) was used as the support to accommodate Keggin-type phosphotungstic acid(HPW) through totally anion-exchange and partly protonating the amino groups on GO surface. The structure of catalyst was characterized by XRD, FT-IR, ICP, XPS, TGA and 31 P MAS NMR. The catalytic performance of the PW-IL-NH-GO catalysts was investigated in selective oxidation of alcohols with aqueous H2O2.5. SnO2 NPs were in situ grown on the GO surfaces via a hydrothermal method using SnCl4.5H2 O as a metal precursor. The procedure placed SnO2 NPs at oxygenated group sites through electrostatic interactions, resulting in sandwich-like SnO2/GO nanocomposite where layers of GO sheet alternated with layers of SnO2 NPs. The structure of catalyst was characterized by XRD, XPS, SEM TGA and TEM. The catalytic performance of obtained SnO2/GO catalysts was evaluated by the Baeyer-Villiger oxidation of ketones with H2O2.