Study On One-Step Green Catalytic Oxidation Of Cyclohexane To Adipic Acid

Adipic acid which is the cyclohexane oxidation product, is the raw material of nylon-66. The growth rate of adipic acid’s industrial demand is greatly. One-step oxidation of cyclohexane to adipic acid becomes one of the most attractive researches in the catalytic industrial areas after the green chemical principle was proposed. Using the environmental friendly technology in the cyclohexane heterogeneous catalytic oxidation becomes an interesting research with the academic and economic value.This thesis is divided into six chapters. It mainly includes the preparation and characterization of activated carbon and activated carbon supported nano-gold catalyst, investigating the catalytic performance for the catalysts in cyclohexane oxidation, then analyzing the catalytic reaction mechanism for both catalysts, and also there is analysis of the solvent effect in the catalytic oxidation.The first chapter is the literature review which summarized the research progress of cyclohexane oxidation catalyst in nearly ten years. This chapter focuses on one-step catalytic oxidation of cyclohexane to adipic acid.The second chapter summarizes the experimental materials, the use of laboratory equipment, as well as characterization methods and experimental methods. It is mainly about:cyclohexane oxidation reaction was carried out in the autoclave, the product was analyzed by gas chromatography and used n-heptane as the internal standard for the processing of experimental data with internal standard method. The catalysts were characterized by ICP-AES. XRD, TEM, XPS, Boehm titration, BET and so on.The third chapter is experimental study of activated carbon catalyst for cyclohexane oxidation. We used different catalyst’s pretreatment methods and characterized the catalyst by BET, XPS, Boehm titration, XRD, and TEM. Investigated the effect of internal diffusion and external diffusion in the reaction and determined the most suitable specific surface area and mesh number of activated carbon catalyst. Investigated the catalytic performance of the activated carbon treatmented by different chemical surface. We found that the activated carbon that treatmented by HNO3had the highest catalytic activity. When74mmol cyclohexane with33mg catalysts reacted under1.5MPa oxygen pressure for8h, at125℃, could give a cyclohexane conversion rate of32.47%and adipic acid selectivity of37.51%. The oxygen-containing functional groups on the activated carbon surface were thought to be the catalytic activity, which activated the cyclohexane and oxygen molecules on the activated carbon surface.The fourth chapter examines the oxidation of cyclohexane on activated carbon supported nano-gold catalyst. The good catalytic effect of Au/C in cyclohexane oxidation generated in the case of the loading amount of1.00%to1.50%.74mmol cyclohexane with33mg catalysts reacted under1.5MPa oxygen pressure for9h, at130℃, could give a cyclohexane conversion rate of46.66%and adipic acid selectivity of52.51%. The catalyst were recycled and used three times, the activity was not significantly reduced. We summarized that, the catalytic mechanism owed to the size effect of gold nanoparticles and the surface of the activated carbon carrier activation.The fifth chapter makes a study of the solvent effect in the catalytic oxidation of cyclohexane. Compared the result of the one-step oxidation of cyclohexane to adipic acid in non-solvent system and solvent system, it proved that the reaction without solvent was poor. Investigating the cyclohexane oxidation on C and Au/C in different solvents, it was proved that the reaction worked best in ketone solvents, and butanone was the most suitable solvent. At last, we explaned the butanone solvent effect from micro angle and analysis of its role in the various stages of free radical reactions.The sixth chapter summarizes the main contents of this article and gives some suggestions on the research and development of the one-step oxidation of cyclohexane to adipic acid on activated carbon and activated carbon supported nano gold catalyst.