Synthesis And Application Of Ordered Mesoporous Metal/Carbon Catalyst

Mesoporous carbon materials have received much attention during recent years because of well-controlled pore structures, high surface areas, and large and tunable pore sizes which facilitate the diffusion of reactant and product inside the pores. Mesoporous carbons are in particular interesting owing to the potential applications as catalyst supports, adsorbents, electrodes, etc. Through isochoric impregnation or one-pot synthesis method, synthesis of ordered mesoporous metal/carbon catalyst. The catalyst exhibits a high conversion of chlorobenzene in coupling reaction, using water as a solvent on a heterogeneous catalyst without any assistance of a phase transfer catalyst. In addition, this heterogeneous catalyst is stable, which shows negligible metal leaching and can be re-used.The thesis is composed of four chapters. The first chapter is a detailed review on the development and research status of mesoporous carbons.Chapter 2 described ordered mesoporous Pd/silica-carbon as a highly active heterogeneous catalyst for coupling reaction of chlorobenzene in aqueous media. Heterogeneous palladium catalysts have been supported on ordered mesoporous hybrid silica-carbon materials which is synthesized by a triblock-copolymer-templating approach. Characterization by XRD, TEM, N2 sorption, FT-IR, TG, XPS and H2-chemsorption techniques reveals the highly ordered mesostructure, high surface areas (~ 345 m2/g), large pore volumes (~ 0.46 cm3/g), uniform mesopore sizes (~ 6.3 nm), hybrid silicate and carbonaceous compositions, and a high dispersion of palladium nanoparticles (about 3 nm) in the mesopores. The catalyst exhibits a high yield for trans-stilbene (54%) in the Heck coupling reaction of chlorobenzene and styrene at 100 oC, and for biphenyl (46%) in the Ullmann coupling reaction of chlorobenzene at 30 oC, using water as a solvent. When substituted aryl chlorides (hydroxyl, methoxyl and methyl) are involved in the Ullmann coupling reaction, the yields of symmetrical substituted biphenyl are also higher than 44% (this value reaches 86% for the Ullmann coupling reaction of 4-chlorophenol) at a low temperature of 30 oC. This heterogeneous catalyst is stable, which shows negligible metal leaching and can be re-used for more than twenty times.In Chapter 3, synthesis of ordered mesoporous Pd/carbon catalyst with bimodal pores and its application in water-mediated Ullmann coupling reaction of chlorobenzene. Heterogeneous palladium catalysts (Pd/OMC) have been supported on the ordered mesoporous carbons (OMC) with bimodal pores which are prepared by the surfactant-templating approach. Characterization using XRD, TEM, XPS, H2 chemisorption and N2 sorption techniques reveals that the Pd/OMC catalysts have the ordered 2-D hexagonal mesostructure (space group of p6mm), extremely high surface areas (~ 1800 m2/g), large pore volumes (~ 1.64 cm3/g), bimodal pores (6.3 nm of primary mesopores and 1.7 nm of secondary mesopores inside the pore walls), hydrophobic carbon surface, and small metal particles well-dispersed inside the secondary small mesopores. This catalyst exhibits a high yield of 43% for biphenyl from the Ullmann coupling reaction of chlorobenzene in water at 100 oC without assistance of any phase transfer catalyst and can be reused up to ten times.In Chapter 4, one-pot synthesis of ordered nickel-containing mesoporous carbon materials. The direct-triblock-copolymer-templating method is demonstrated to synthesis ordered nickel-containing mesoporous carbon materials by using phenolic resin as carbon precursor and nickel nitrate as nickel precursor. The materials possess high surface areas (600 - 700 m2/g), large pore sizes (~ 4 nm), large pore volumes (0.4 - 0.5 cm3/g) and well-dispersed small nickel nanoparticles inside the pore walls.