Modification Of Solid Acid Catalyst Under Mild Conditions Catalyzed Oxidation Of Cyclohexane Reaction

With the development of the industry in recent years, people focus a major concern on the problem of environment and energy. Cyclohexane catalytic oxidation to produce cyclohexanol and cyclohexanone is an important reaction in industry. Past studies showed that there are many problems in this process, such as low conversion, low selectivity, high energy consumption and the problem of three wastes. Therefore, the developing trend of catalytic oxidation of cyclohexane is to find a new technical process to improve catalytic efficiency, reduce cost and energy consumption, and decrease environmental pollution.In this thesis, two kinds of solid acid catalysts were prepared. One was metal oxide modified superacid, the other was superacid modified kaolin solid catalyst. The characterization of the catalysts was performed using electron microscopy (SEM), X-ray diffraction (XRD), infrareds spectroscopy (IR), X-ray photoelectron spectroscopy (XPS) and so on. Moreover, the application of the catalysts was studied in the reaction of catalytic oxidation of cyclohexane under mild condition. The catalytic properties of the catalysts were evaluated by the main product distribution and improved by the modified experiment setup. According to the results of the XPS and UV, the possible mechanism was discussed. Owing to its high catalytic activity and efficiency, the modified solid acid catalyst is economic for a wider range of markets.In the first part of the thesis, the basic knowledge of species and characteristic of the solid acid catalyst was introduced; the formation mechanism of acid intensity, catalyst preparation, modification method and the application of the catalyst were reviewed emphaticallyIn the second part of this dissertation, catalytic oxidation of cyclohexane at a room temperature over modified solid superacid was investigated. The catalysts were characterized by TG-DSC, XRD and SEM and the effect of different catalysts (TiO₂, SO₄^2-/TiO₂ and SO₄^2-/TiO₂-Co₂O₃) in the catalytic reaction was also studied. It was found that SO₄^2-/TiO₂-Co₂O₃ was superior in catalytic activity to the other catalysts, and it can be reused. The possible mechanism of the product was proposed simply.The third part of this thesis, the superacid modified kaolin as a new catalyst was prepared. Catalytic oxidation of cyclohexane at 81℃over modified kaolin was investigated. The catalysts were characterized by TG-DSC, SEM and IR spectra and the effect of different catalysts (SO₄^2-/TiO₂-Ce₂O₃ modified kaolin, SO₄^2-/TiO₂-Al₂O₃ modified kaolin and SO₄^2-/TiO₂-Fe₂O₃ modified kaolin) in the catalytic reaction was also studied. It was found that the good product distribution can be obtained in the short time, and SO₄^2-/TiO₂-Ce₂O₃ modified kaolin had highest catalytic activity for catalytic oxidation of cyclohexane.In the forth parts, the photocatalytic activity of the modified TiO₂-based solid superacid was investigated by photocatalytic oxidation of cyclohexane at room temperature. The acidity and surface area of the catalysts were characterized by IR and BET measurement. The effect of different catalysts (TiO₂, SO₄^2-/TiO₂ and SO₄^2-/TiO₂-ZrO₂) in the photocatalytic reaction was studied. The results showed that the photocatalytic activity of SO₄^2-/TiO₂-ZrO₂ was higher than of unmodified TiO₂ and the deep oxidative activity was improved when UV radiation was applied. The photocatalytic possible mechanism was proposed.