Metal Oxide Catalysts Preparation And The Catalytic Performances In Tetralin Oxidation

α-tetralone is an important organic intermediate, mainly applied in the synthesis ofmethyl naphthol and the medicines such as sertraline used as an antidepressant.Traditionally, α-tetralone is produced by tetralin oxidation using the chromium acetateand2-methyl-5-ethyl pyridine compound homogeneous catalyst, which has somedisadvantages: the catalyst is poisonous and a considerable amount needed,irrecoverable and causes serious environmental pollution. As a result, it becomesincreasingly urgent that research and development of an environment-friendlytechnology for synthesizing α-tetralone through the tetralin catalytic oxidation.In this dissertation, using cheap γ-Al2O3as the catalyst carrier, chromium catalystsCr2O3/γ-Al2O3and manganese catalysts MnO2/γ-Al2O3were prepared by the incipientimpregnation method; these two kinds of catalysts were modified respectively bydoping metal oxide promoters. The activities of as-doped catalystsCr2O3-CeO2/γ-Al2O3and MnO2-CoO/γ-Al2O3were higher than those undoped. Thesecatalysts were characterized by XRD, UV-Vis DRS, TG-DTA and pyridineadsorption-IR. Furthermore, the influences of catalyst preparation conditions andoxidation reaction conditions on the catalytic performances were investigated. Mainresearch contents and results are shown as follows:The optimal conditions for preparing chromium catalyst: Cr2O3loading7.5%,calcined at500℃for4h. A conversion of50.1%of tetralin and a selectivity of79.7%of α-tetralone were obtained over the7.5%Cr2O3/γ-Al2O3catalyst under the reactionoxidation condition of120℃, catalyst60mg and8h, with a good stability. Theresults of UV-Vis DRS and TG-DTA showed that: the active species of the catalystswere dominantly Cr2O3dispersed highly on the surface of γ-Al2O3, containing a smallamount of CrO3.The optimal conditions for preparing manganese catalyst: MnO2loading10%,calcined at550℃for4h. The prepared catalyst10%MnO2/γ-Al2O3presentedexcellent catalytic properties. A conversion of49.8%of tetralin and a selectivity of89.0%of α-tetralone were obtained over the10%MnO2/γ-Al2O3catalyst under thereaction oxidation condition of120℃, catalyst100mg and8h,. The results of XRDand TG-DTA showed that: the active species of MnO2/γ-Al2O3catalysts weredominantly MnO2containing a small amount of Mn2O3. The results of the adsorption of pyridine-IR showed that a decreasing amount of acidity on the surface of thecatalyst was beneficial for the catalytic performance.These two single-active-component catalysts were modified by doping. The resultsshowed that: when the Cr/Ce molar ratio was6,10.5%Cr2O3-CeO2/γ-Al2O3catalyst,prepared by calcining at500℃for4h, demonstrated the best catalytic performances,giving a conversion of tetralin of41.6%under the reaction condition of90℃and6h.The Cr2O3-CeO2/γ-Al2O3catalyst had the advantages of high activity at lowertemperature. When Mn/Co molar ratio was3,20%MnO2-CoO/γ-Al2O3catalystprepared by calcining at550℃for4h, presented better catalytic activities,demonstrating a conversion of tetralin of50.1%and a selectivity of α-tetralone of79.7%under the reaction condition of120℃and8h. the results of XRD showed that:CoMnO3with spinel type structure was formed as Co and Mn calcined at550℃.This dissertation has an important theoretical significance and higher applicabilityfor researching and developing heterogeneous catalysts and environment-friendlytetralin oxidation technologies.