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Synthesis And Application Of Mesoporous Carbon Nanoparticles Supported Gold And Palladium Catalysts

Posted on:2017-01-06Degree:MasterType:Thesis
Country:ChinaCandidate:H B FuFull Text:PDF
GTID:2131330485963167Subject:Physical chemistry
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Porous carbon materials have been widely applied in catalysis, adsorption and separation due to their opened frameworks, large specific surface areas and ordered pore structures. The mesoporous carbon nanosphere material not only has excellent properties of mesoporous materials, while combining quantum size effect of nano-materials and other advantages, makes this nano-mesoporous material into a unique new mesoporous materials. Gold or palladium catalyst has attracted much attention by scientists. Especially, gold or palladium nanoparticles with small size have high catalytic activity to selective oxidation reaction. But how to get the Au or Pd NPs that have concentrated size distribution and high stability is still challenging. And supporting Au or Pd NPs on carbon matrix is a difficult work.This thesis focus on exploring feasible synthesis routes for load of gold or Palladium nanosized mesoporous carbon materials and investigating suitable applications for them. Firstly, this study proposes novel gold-intercalated ordered mesoporous carbon nanosphere catalysts to efficiently catalyze the selective hydrogenation of aromatic nitro compounds. The spherical morphology with a size of approximately 90 nm, high surface areas(approximately 600 m2·g-1), large pore volumes(approximately 0.4 cm3·g-1), and uniform mesopore sizes(2.4 nm), gold nanoparticles with a diameter of 2.8 nm. Aggregation is inhibited either at a high-temperature treatment at 700°C. The Madon-Boudart test shows that nanospherical catalysts exhibit no diffusion limitations in the reduction of nitroarenes, even for a large 2.6-dimethylnitrobenzene molecule. The nanospherical mesoporous carbon-supported gold catalysts are highly active and selective for the reduction of nitroarenes to corresponding amines using both sodium boride and H2 as reduction agent. The TOF values can reach 13.8, 16.0, 7.7 and 25.8 min-1 for converting 4-nitrophenol, 2-nitrophenol, 4-(tert-butyl)-2-nitrophenol, and 2.6-dimethylnitrobenzene with sodium boride, respectively; 14.2 and 27.8 min-1 for converting 4-nitrophenol and p-chloronitrobenzene with H2, respectively. The catalysts are stable and can be re-used more than 15 times. The hot infiltration test, together with the trapping test using mercapto-functionalized SBA-15 solids, shows that the soluble gold species are undetected during successive catalytic runs. The high activity and stability of ordered mesoporous carbon nanosphere-supported gold catalysts. Secondly, Palladium on carbon mesoporous nanospheres synthesized catalyst material after load of nitrogen-doped. The spherical morphology with a size of approximately 100 nm, high surface areas(approximately 222 m2·g-1), large pore volumes(approximately 0.25 cm3·g-1), and uniform mesopore sizes(3.5 nm), Palladium nanoparticles with a diameter of 3.5 nm. Cinnamic aldehyde and the aqueous phase is applied to a high-pressure hydrogenation of cinnamic aldehyde in 3 h to achieve complete conversion. All generated 3-phenylpropyl aldehyde selectivity of up to 100%.In chaper 4, the whole thesis is summarized.
Keywords/Search Tags:ordered mesoporous carbon nanosphere, gold nanoparticles, Palladium nanoparticles, selective hydrogen
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