Catalytic Oxidation Of Limonene To Carvone Over Analogous MOF Of Mn(BTC)and Manganese And Iron Doped MIL-101(Cr)

Carvone derived from the oxidation of limonene is one of the most valuable product for its wide applications in food additives,fragrance and pharmaceutical industries.However,there are many by-products derived by oxidation of limonene.Carvone is of considerably low selectivity in heterogeneous catalytic processes.Therefore,taking into account the economic and environmental factors,to develop highly selective catalysts for the production of carvone under mild conditions is urgently required.Metal-organic frameworks(MOFs)are nanomaterials with hybrid organic-inorganic supramolecular structures.MOFs have recently attracted tremendous attention in catalysis and adsorption process owing to their advantages such as high surface areas,well-defined structures,special metal centers,the ease of processability and structural diversity.However,the application of MOFs in selective allylic oxidation of alkene was still very limited.In this paper,the catalytic oxidation of limonene by metal organic framework(MOFs)was carried out.(1)X/MIL-101(Cr)(X= Fe3+,Co2+,Mn2+,Ni2+,Cu2+,Ag+,Cd2+)was prepared by doping method and Mn(BTC)was prepared by Solvothermal method.The above-mentioned materials were characterized by means of infrared spectroscopy(IR),scanning electron microscopy(SEM)and thermogravimetric analysis(TG),etc..(2)Catalysts was synthesized by hydrothermal method and displayed good catalytic properties for oxidation of limonene to carvone.The effects of solvents,oxidants,reaction temperature on the productivity,as well as the reaction time were investigated.Considering the effect on both conversion of limonene and selectivity of carvone,Fe/MIL-101(Cr)as the catalyst,we chose 3%(Fe/Cr molar ratio)as the doping amount of Fe,40 mg as the suitable catalyst amount,17 mmol 70%tert-butyl hydroperoxide(TBHP)as oxidant amount,non-solvent,70 ? and 20 h as the suitable reaction temperature and time for the oxidation of limonene.Under this condition,Fe/MIL-101(Cr)exhibited reasonable substrate product selectivity(60.0%)and conversion(28.5%).When Mn/MIL-101(Cr)is used as catalyst,5%(Mn/Cr molar ratio)as the doping amount of Mn,60 mg as the suitable catalyst amount,24 mmol 70%tert-butyl hydroperoxide(TBHP)as oxidant amount,3 mL tertbutyl alcohol as solvent,50 ? and 32 h as the suitable reaction temperature and time for the oxidation of limonene.Under this condition,Mn/MIL-101(Cr)exhibited reasonable substrate product selectivity(38.3%)with conversion(55.8%).When Mn(BTC)is used as catalyst,20 mg as the suitable catalyst amount,air as oxidant amount,non-solvent,50 ? and 24 h as the suitable reaction temperature and time.Under this condition,95.0%substrate conversion and 32.6%selectivity for carvone was obtained.