| The oxidation of olefins to oxygenated derivatives has a large scale applications in the chemical industry and has been extensively studied.At present,a variety of catalysts have been developed for the oxidation of olefins.However,these catalysts have the problems of polluting the environment and easily losing active sites during preparation and catalysis.Ionic liquids,as a research hotspot of green chemistry,are widely used as green solvents and catalysts.However,ionic liquids,as a class of heterogeneous catalysts,are difficult to recover and high contents of ILs needed in the reaction media,which limits the application of ionic liquids.Ionic liquids-based catalyst is often used as heterogeneous catalysis and shows excellent catalytic performance.However,there are only a limited number of reports on the catalysis of olefin oxidation using ionic liquids-based catalysts.Therefore,it is very important to develop the ionic liquids-based catalysts for olefin oxidation.In this paper,different ionic liquids-based catalysts were synthesized.Their physical and chemical properties were characterized,and the applications in the oxidation of cyclohexene and styrene in the presence of oxygen were studied.Specific research contents are as follows:1.Polyoxometalates-based poly(ionic liquid)s is synthesized by cross-linking polymerization and anion exchange based on 1-vinyl-3-hexylimidazole bromide ionic liquid(HVIM).And it was applied in the oxidation of cyclohexene in the presence of oxygen.The experiment was carried out to investigate the effect of different catalyst structures and reaction conditions on cyclohexene oxidation.The research results show that the prepared PHAD1-PMo catalyst has a high specific surface area and excellent catalytic activity.The conversion rate of cyclohexenis is 76.0%,and the selectivities of Cyclohexene oxide,2-Cyclohexen-1-ol and 2-Cyclohexen-1-one were 12.4,19.9 and 49.3%,respectively,under the appropriate conditions: a reaction temperature of 130?,an oxygen pressure of 0.8 MPa,a catalyst dosage of 40 mg,an reaction time of 6 h.And the catalyst,as a solid catalyst,can be easily recovered.There was no significant decrease in activity after reusing 5 times.2.Transition metal-doped Polyoxometalates-based poly(ionic liquid)s are prepared by introducing transition metals and being used as catalysts for oxidation of cyclohexene in the presence of oxygen.The effects of different Keggin-type polyoxometalates and transition metals on the performance of the catalyst were explored.The effects of different reaction conditions on the oxidation process of cyclohexene was investigated in detail.The experimental proof that Cu doped polyoxometalates-based poly(ionic liquid)s PDVD-PWCu3% has the highest catalytic activity for the oxidation of cyclohexene.The conversion rate of cyclohexene reached 75.9%,the selectivities of Cyclohexene oxide,2-Cyclohexen-1-ol and2-Cyclohexen-1-one were 15.2,15.8 and 45.5%,respectively,under the appropriate conditions: a reaction temperature of 90?,an oxygen pressure of 1 MPa,a catalyst dosage of 30 mg,a reaction time of 6 h.The activity of the catalyst did not decrease significantly after being reused 5 times,which show that PDVD-PWCu3% has good reusability.3.Transition metal-N-doped carbon material was synthesized using carboxyl functionalized ionic liquid as carbon source,and melamine as N source and porogen.The transition metal-N-doped carbon material was applied for oxidation of styrene.It is found that the 5%Fe-N/C-900 has the highest catalytic activity,and its specific surface area is 201.7 m2/g.The conversion of styrene was 58.8% and the selectivity of benzaldehyde was 64.1% under the appropriate conditions: an oxygen pressure of 1.2 MPa,a catalyst dosage of 30 mg,a reaction temperature of 90 ?,and a reaction time of 8 h.In addition,the catalyst activity remained unchanged significantly after 5 times of reuse.All these results demonstrate that theprepared catalysts show good application prospects. |
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