The Preparation Of M-ZSM-5(M=V, Cr, Mn) And Its Catalytic Performance In The Cyclohexane Oxidation

In this dissertation, the ZSM-5 molecular sieves catalysts modified by transition metal were prepared by the direct hydrothermal (DHT) method. The structure properties of samples were characterized by XRD, XRF, SEM, FT-IR, UV-vis spectroscopy and N2 adsorption-desorption, which showed that the transitional metal atoms could be incorporated into the framework of the molecular sieves and all the samples held the typical structure of MFI. The ZSM-5 molecular sieves possess a larger surface area and pore volume after modification. The catalytic performance of the M-MFI (M=V, Cr, Mn) samples were investigated in the catalytic oxidation of cyclohexane with molecular oxygen as oxidant agent in a solvent-free system. The reaction conditions were optimized and the best catalyst for the reaction was selected.The catalyst activity and selectivity of M-MFI is greatly improved after modification due to the creation of new redox active center. The optimum reaction conditions in the liquid solvent-free oxidation of cyclohexane with molecular oxygen as oxidizer was:oxygen pressure at 1.0 MPa, reaction temperature at 120℃and reaction time for 3 hours. Catalysts modified with different metal leaded to different catalytic properties. The conversion of cyclohexane and selectivity of KA oil using 0.15g 3wt%V-ZSM-5 as catalyst was 14.87% and 92.64%, respectively. The conversion of cyclohexane and selectivity of KA oil using 0.12g 2wt%Cr-ZSM-5 as catalyst was 11.43% and 88.21%, respectively. The conversion of cyclohexane and selectivity of KA oil using 0.15g 8wt%Mn-ZSM-5 as catalyst was 10.68% and 90.17%, respectively.