Catalytic Oxidation Of Cyclohexane And Cyclohexene By Modified TS-1 Molecular Sieve

As a unique MFI structure of the new microporous functional materials,TS-1molecular sieve has attracted much attention,which has many advantages in heterogeneous reaction by hydrogen peroxide such as mild reaction conditions,environmentally friendly and excellent catalytic performance.TS-1 is connected by10-ring pore openings,which was reported for their better selective oxidation activity of organic molecules such as olefins,aromatics.However,the difficulty of large molecules transport within such microporous channels is also existed.Therefore,modification of titanium silicalite molecular sieve has attracted the attention of researchers.The selective oxidation of relatively inert C–H bonds of alkanes is one of the most challenging problems.It is easy to be further oxidized to peroxide or other low carbonic acid,and even deep oxidation to CO₂ and H₂O.As the C–H bond activation energy of hydrocarbons is higher and the thermodynamics of intermediates are unstable.Therefore,the study of C–H bond catalytic oxidation systems remains the subject of focus investigations.Based on the excellent catalytic performance and attractive application prospect of TS-1 molecular sieve in the process of industrial oxidation such as epoxidation of propylene,hydroxylation of benzene and ammoximation of cyclohexanone,a new mesoporous molecular sieve catalyst was prepared by internal reaming design and surface modification of transition metal on TS-1 molecular sieve to catalytic oxidation of hydrocarbon C–H bond.Experiments were carried out to prepare adipic acid and cyclohexenone by catalytic oxidation of cyclohexane and cyclohexene respected.Here we developed a hollow H₂WO₄/TS-1 bifunctional catalyst with excellent catalytic activity for the direct transformation of cyclohexane to adipic acid with30%H₂O₂ by non-HNO₃ route.Oxidation decomposition product of H₂O₂ oxidant is water,which is environment friendly.A cyclohexane conversion of 31%and 78%adipic acid selectivity was achieved over this catalyst calcinated at 500?.XRD,XPS,TEM,FT-IR and UV-vis spectroscopies were used to characterize catalysts with understanding of the structure of active species on the hollow TS-1 support.The new MTS-1 catalyst was prepared by a facile hydrothermal method and it was used in selective catalytic oxidation of C–H bond of cyclohexene in this work.The results of cyclohexene oxidation showed that the catalytic performance of MTS-1was quite remarkable and the catalytic activity over recycled catalyst remained at a high level after ten cycles.The structure of the catalyst was analyzed by XRD,TEM,FT-IR and UV-vis spectroscopy.