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The Design,Synthesis Of Highly Efficient Catalysts Based On Mesoporous Silica And Catalytic Performance In Aerobic Oxidation Reaction

Posted on:2019-04-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:X Y ZhangFull Text:PDF
GTID:1311330566964541Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
The mesoporous silica materials have large specific surface area,adjustable pore size,abundant surface silicon hydroxyl which is easy to modify,good hydrothermal stability,controllable morphology and simple synthetic procedures.Based on the above advantages,different kinds of mesoporous silica materials and corresponding catalysts were prepared,and then the catalytic activities and reusability of the catalysts were systematically evaluated in organic oxidative reactions.The following works have been carried out:(1)An efficient catalyst SBA-16-pro-Cu(I)based on the SBA-16(which has the cage-like mesoporous structure)as the support and Cu(I)as active sites has been successfully prepared and applied in synthesis of ?-ketoamides.In the process,the catalyst demonstrated high catalytic activity(up to 88%)in the direct oxidative synthesis of ?-ketoamides between acetophenone and piperidine,employing O2 from open air as the oxidant without other additives.The expansion of a series of ketones and amine substrates has good conversion and selectivity.The heterogeneous catalyst was applied in this reaction for the first time,and the catalyst could be easily recovered from the reaction system through simply filtration and reused several times without a significant loss of activity.(2)In this work,a hollow tubular mesoporous silica materials,employed multi-walled carbon nanotubes as hard template,were successfully developed,with copper-iron composite oxides in the tube as catalytically active sites.The resulting CFO@Si O2 was applied in the selective oxidation of cyclohexane and showed good catalytic activity in solvent free conditions.With H2O2 as oxidant,the conversion of cyclohexane was 74% and the selectivity of cyclohexanone was 71%.The mesoporous structure and hollow structure of CFO@Si O2 improved the selectivity of desired products,avoiding the generation of adipic acid.In addition,the CFO@Si O2 has good dispersibility in water,and could be recovered by simply filtration.Moreover,the catalyst reused for several times without substantial loss of activity.(3)In this work,a simple and environmentally benign approach for highly selective preparation of ?-caprolactone by oxidation of cyclohexanone has been carried out,which employed metal-free mesoporous silica(m Si O2)nanorods as catalyst under atmospheric pressure.The applied metal-free silica catalyst showed efficient catalytic performance for the B-V oxidation of various cyclic ketones and aliphatic ketones with O2/benzaldehyde as oxidant.The catalyst could be easily separated from the reaction system by filtration and reused several times without significance loss of activity.Moreover,electron paramagnetic resonance(EPR)spectra of the reaction were obtained,indicating the existence of benzoyloxyl radical.The mechanism study of the reaction demonstrated that the super large surface area diluted the concentration of radicals and the adsorption of radicals could protect the radical species from inhibition.
Keywords/Search Tags:mesoporous silica materials, the synthesis of ?-ketoamides, solvent-free, oxidation reaction of cyclohexane, metal-free catalysis, Baeyer-Villiger oxidation reaction
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