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Hydrocarbon Oxidation Over Co-Based Catalysts With O2 As Oxidant

Posted on:2008-09-17Degree:MasterType:Thesis
Country:ChinaCandidate:X Z SunFull Text:PDF
GTID:2121360242458915Subject:Industrial Catalysis
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In the oxidation process, the oxidation of cyclooctene to epoxide and the oxidation of cyclohexane to cyclohexanol and cyclohexanone are two important industrial production processes. Epoxide is an important intermediate in organic synthesis,which are widely used in the petrochemical, fine chemical, organic synthesis, pharmaceutical, perfume and electronics industries, cyclohexanol and cyclohexanone are important intermediates in the synthesis of caprolactam, adipic acid, as well as medicine, and fine chemicals.This paper,just through the use of cleaner oxidant-molecular oxygen, cyclooctene and cyclohexane oxidation experiments as a research object, in a different way and by different method, prepared heterogeneous cobaltic catalyst under different conditions,further more obeserved catalytic properties of the catalysts, and through a variety of physico-chemical techniques for the characterization .I Catalytic properties of the cobalt-based catalysts prepared by different methods in the oxidation of cyclooctene.(1) We prepared different cobalt-based catalysts by sol-gel method, ion-exchange method, impregnation method and flexible ligand method, and observed the catalytic performance in the oxidation of cyclooctene , the catalysts show a different catalytic performance, in which the catalysts prepared by sol-gel method show the best catalytic activity, At 100℃,when reaction time was 5 hours , conversion of cyclooctene could reach to 29.90%.(2) In the process of preparing catalysts by sol-gel method, parameters of preparation is the main factors which affect the catalytic performance of catalysts, in which the pH value was the key factor. Preparation of the catalysts with pH value 5,7,8,9,10,and we observed the effect on physicochemical properties and catalytic properties during the preparation process .The result show that the catalysts prepared under different pH value had not only different surface area, Co content, yield, reduction properties and acidic properties but also different catalytic properties. Under the same reaction conditions, the catalyst prepared under pH=8 had the best catalytic activity in the oxidation of cyclooctene.(3) We observed the catalytic performance of catalyst prepared under pH=8 by changing the reaction condition such as the reaction time, reaction temperature, solvent, substrate, quality of catalyst. The result was the best when we used 1,4-dioxane as solvent, cyclooctene as substrate ,and 0.1g catalyst. The catalyst could be used five times without losing activaty, with strong stability.II Catalytic properties of the cobalt-based catalysts prepared by different methods in the oxidation of cyclohexane.(1) We prepared different cobalt-based catalysts by sol-gel method, ion-exchange method, impregnation method and flexible ligand method, and observed the catalytic performance in the oxidation of cyclohexane, the catalysts show a different catalytic performance, in which the catalyst Co/Y prepared by ion-exchange method show the best catalytic activity.(2) We characterized the catalysts prepared by ion-exchange mothed with ZSM-5,MCM-22,Beta,Mordenite and Y zeolite as matrix by X ray diffraction,UV-vis, elemental analysis. The XRD spectra diffraction show that the matrix of different catalysts was not destroyed, Moreover, the high dispersion of cobalt atom without aggregation .The UV-vis show that the Co element was present in tetrahedron without oxidation. Result of elemental analyst show the loding of Co had relation with Si/Al of the matrix, higher Si/Al, lower loding.(3) The catalysts prepared by ion-exchange method with the Y-zeolite as matrix have the best catalytic performance among the catalysts, the total yield of KA oil (the mixture of cyclohexanol and cyclohexanone) can reach to 12.55%, the selectivity of KA oil can reach to 79.03% under 1.2MPa O2, when the reaction temperature was 130℃and reaction time was 3h.(4) We observed the catalytic performance of catalyst with the Y-zeolite as matrix by changing the reaction conditions such as reaction temperature, reaction time, the quality of initiator. The result show the best at 130℃, when the reaction time was 3h, and the ratio between initiator and cyclohexane reached to 0.027. The catalyst could be used five times without losing activity , with strong stability.
Keywords/Search Tags:oxygen, oxidation, cyclooctene, cyclohexane, cobaltic catalyst, zeolite, sol-gel
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