Investigation Of Composite Nanocatalysts Transforming Gaseous Cyclohexane Into Cyclohexene

In this thesis, cyclohexene preparation acted as the target reaction by selectively catalytic oxidation dehydrogenation of gaseous cyclohexane. A series of TiO₂,MoO₃/TiO₂,MoO₃-MO/TiO₂(MO=K₂O, V₂O₅, Al₂O₃),MoO₃-K₂O-V₂O₅/TiO₂ were prepared by sol-gel method, and also characterized by Differential Scanning Calorimetry Thermogravimetry(DSC-TG), Transmission Electron Microscope(TEM), X-ray Diffraction(XRD) and Fourier Transform Infrared(FT-IR). The target reaction was systematically researched.â‘ During the process of preparation of TiO₂ nanoparticles, the appearance, the crystal types and its contents of TiO₂ nanoparticles are controlled very well through changing concentration of raw materials,charging mode,aging periods. In this study, having not depended on the calcining temperature, we make the method of entirely transforming from anatase phase to rutile phase. The evaluation results of the catalyst activity showed that anatase phase TiO₂ nanoparticles exhibited higher catalytic activity than rutile phase.â‘¡MoO₃ was distributed on the carrier of TiO₂ with manolayer and multilayer. The atom Mo formed the bond with O-Ti in the manolayer structure, and the surface water molecules of TiO₂ was dissociated, and the activity centre of Mo⁶⁺ and Mo-O^- was formed by means of activating to drop the hydroxyl group; Mo=O and Mo-O^- were the main activity species in the presence of multilayer structure. The dehydrogenation centre exited the synergetic effect with the oxygen-supply centre, K,Al,and V can influence the synergetic effect.â‘¢The catalyst constitutions and the reaction conditions were optimized by the orthogonal test. The results showed that the catalysts containing 4 wt% Mo, 2.5 wt% K, 3.9 wt% V₂O₅ exhibited high activity. The optimal reaction conditions in the target reaction were reaction temperature 310℃, the gas flow rate is 55 mL·min^-1, the volume ratio between cyclohexane and O₂ is 1.6. Under the optimization condition, the selectivity of the cyclohexene can reach 89% and the conversion of the cyclohexane is 32%.â‘£The activation ambience, reaction temperature, catalyst's send live time, gas flow rate were used to study the best catalyst. In the activation gas, the gas phase oxygen content should be controled between 20% 25%; the reaction temperature...