Study Of Gas-phase Aerobic Oxidation Of Cyclohexane Over Metalloporphyrin-Zeolite Catalysts

The selective oxidation of saturated hydrocarbon compounds has been a hot issue in the academic and industrial research of chemical industry. Saturated alkanes, are usually stable, and chemical inertness. More harsh conditions must be used to translate them into chemical products or raw materials. But side-reactions will inevitably increase in these conditions, resulting in poor atom economy and bring the problems of energy consumption. This not only caused environmental pollution and waste of resources, but also increased the cost of production substantially.Gas-phase oxidation process has a higher conversion and higher capacity, which is suitable for large-scale batch process. It becomes the hot issure of catalytic oxidation in recent years, and is also the future developing direction. Metalloporphyrins were widely used in the catalytic oxidation of hydrocarbons with excellent catalytic performance, and have made great progress in the field of alkane oxidation and olefin epoxidation. Catalysts of metalloporphyrin supported on zeolite show a better catalytic performance and stability than homogeneous metalloporphyrin catalysts in the liquid phase reaction system, which provides new research ideas.The catalysis of metalloporphyrins supported on zeolites in the gas-phase catalytic oxidation system was first reported in this thesis. It proved the feasibility of the system, and conducted a preliminary exploration and research. The main contents are as follows:1, Introduced experimental process of gas-phase oxidation of cyclohexane by metalloporphyrin supported on zeolite. Developed and optimized a GC analysis method to analysis of the oxidation product cyclohexane, cyclohexene, pentanal, cyclohexanol and cyclohexanone;2, The concept and process design of the biomimetic catalytic fixed-bed reactor was presented. And corresponding adjustments and improvements needed by the experiment were made.3, Six types of metalloporphyrins were synthesized and supported on 13 X zeolite, used as catalysts for gas-phase oxidation of cyclohexane. After the initial exploration and optimization of the new system, the catalytic performance of metalloporphyrin / 13 X catalysts are compared and screened. Among these catalysts, TPPCo/13X has a high conversion of cyclohexane and better selectivity of cyclohexanol, cyclohexanone and pentanal. Mesoporous zeolite Al-MCM-41 was also synthesized. Catalysis of TPPCo supported on Al-MCM-41 and 13X were also investigated;4, The effects of reaction conditions such as temperature, cyclohexane / O2 ratio and the reaction space velocity (including catalyst loading and gas flow rate), and other factors on the gas phase catalytic oxidation of cyclohexane using TPPCo/13X as the catalyst were investigated. In the condition of 1.5 MPa, 265 oC, air flow speed of 50 SCCM, cyclohexane feed speed of 0.066 mL / min, TPPCo/13X catalyst weight 1.5 g, cyclohexane conversion was 7.4%, the total selectivity of cyclohexanol, cyclohexanone and pentanal was 87.5%. The stability of the catalyst was also investigated under the optimum condition. The conversion of cyclohexane was droped from 7.4% (balance) to 6.9% after 10 h in the continuous reaction, which suggested the stability of the catalyst in this reaction system. Based on the experimental data and phenomena, a possible reaction pathway of the main products was presented.In a summary, a new gas-phase biomimetic catalysis system of cyclohexane oxidation over metalloporphyrin-zeolite was established, and the catalytic performances of different metalloporphyrin-zeolite catalysts were investigated and the influences of reaction conditions were discussed. Metalloporphyrin-zeolite catalyzed gas-phase oxidation of hydrocarbons is a complementary field to the liquid-phase oxidation, and it greatly expands the field of hydrocarbon oxidation catalyzed by metalloporphyrins. This thesis provides new materials in the theoretic and application aspects of biomimetic oxidation of hydrocarbons by metalloporphyrins, and is of importance to develop new oxidation route of hydrocarbons.