Preparation Of Supported Solid Acid And Catalytic Activity In Baeyer-Villiger Oxidation Of Cyclic Ketones

Porous materials are widely used in biological, phase separation, energy storage,molecular sieve, catalytic carrier etc, because its huge specific surface area,topography, structure controlled and modifiable characteristics. The preparation ofporous materials by template becomes a hot issue. In this paper, we successfullyprepared porous tubular γ-Al₂O₃and AlPO₄-5molecular sieve, using cotton fiber andtriethylamine as templates respectively. Supported solid acid catalysts were obtainedby chemical tailoring method and hydrothermal synthesis method, their catalyticperformance were investigated by Baeyer-Villiger oxidation of ketones.Porous tubular γ-Al₂O₃was synthesized through immersion method usingaluminium choride as aluminum source and cotton as template. Mesoporousγ-Al₂O₃-AlBrx（x=1～3）could be prepared by chemical tailoring method usinghydrobromic acid as tailoring agent. The morphology, surface area, pore volume, poresize and characteristic of the γ-Al₂O₃-AlBrx（x=1～3） could be controlled by usingdifferent concentration of hydrobromic acid. Three kinds of γ-Al₂O₃-AlBrx（x=1～3）catalysts were proved to be efficient and reusable catalysts for Baeyer-Villigeroxidation of ketones in the presence of30%H2O2under mild conditions. The effect ofthe solvent, time, temperature and the amount of catalyst were investigated in details.It was found that γ-Al₂O₃-AlBrx-2has the highest catalytic activity amongγ-Al₂O₃-AlBrx-n （n=1,2,3）, and many cyclic ketones could be efficiently convertedinto the corresponding lactones with90%conversions （21%-86%yields） and highselectivities under the optimum reaction conditions. The catalyst could be be reused atleast three times.The AlPO₄-5was synthesized through hydrothermal synthesis method usingaluminum-isopropoxide as aluminum source and triethylamine as structure-directingagents. The AlPO₄-5-AlBrx（x=1～3） could be prepared using hydrobromic acid astailoring agent. The morphology, surface area, pore volume, pore size andcharacteristic of the AlPO₄-5-AlBrx（x=1～3） could be controlled by using differentconcentration of hydrobromic acid. Three kinds of AlPO₄-5supported AlPO₄-5-AlBrx（x=1～3） catalysts were proved to be efficient and reusable forBaeyer-Villiger oxidation of ketones in the presence of30%H2O2under mildconditions. The effect of the solvent, reaction time, temperature, and the amount ofcatalyst used were investigated in details. The result showed that the AlPO₄-5-AlBrx-2has the highest catalytic activity and could be reused; some ketones could beoxidation to corresponding ester with high conversion and good selectivity.The WAlPO₄-5was synthesized through hydrothermal synthesis method usingaluminum-isopropoxide as aluminum source, triethylamine as structure-directingagents and phosphotungstic acid as tailoring agent. The tungsten was successfullydoped in aluminum phosphate through the synthesis. Catalysts with different W/Almolar ratio were proved to be efficient and reusable catalysts for Baeyer-Villigeroxidation of ketones in the presence of30%H2O2under mild conditions. The effect ofthe solvent, reaction time, temperature and the amount of catalyst used wereinvestigated in details. The result showed that the catalysts have high catalytic activityand could be reused; some ketones could be oxidation to corresponding ester withhigh conversion and good selectivity.