Study On Catalytic Activation Of Shenfu Briquette Semi Coke With Carbon Dioxide/Steam

Low temperature pyrolysis is an important technical way to achieve the grading utilization of Shenfu coal. At present, the clean conversion of the char from semicoke industry, and catalytic activation（partial gasification） of the char from the new process of coal catalytic pyrolysis integrated with char activation, both involve the technology of char utilization with high added-value and the theory breakthrough. Therefore, in this thesis, the catalytic activation process of semi coke, which from the low temperature catalytic pyrolysis of Shenfu briquette, was investigated by using carbon dioxide and steam as activator. To explore a new method for preparation of coal based activated carbon, and to provide technical and theoretical support for the quality-based utilization with high added value of Shenfu coal and its semi coke.In this paper, the influence of activation conditions, the proportion of carbon dioxide and steam in activator, supported Mo-based catalyst and supported Fe-based catalyst on the properties of activated carbon and gas product distribution were studied in the fixed bed reactor by means of activated carbon iodine value and methylene blue value analysis, nitrogen adsorption, scanning electron microscopy, X- ray diffraction and the analysis results of gas compositions by gas chromatography.In CO₂ atmosphere, the influence of the activation temperature, activation time and the flow of CO₂ on activated carbon yield and its adsorption performance, and composition distribution of gas product were investigated. The results show that, the iodine adsorption value, methylene blue adsorption, BET surface area of activated carbon was 783mg/g, 70mg/g, 585m²/g separately under the condition of activation temperature 850 ℃, activation time 120 min, the flow of CO₂ 500mL/min. In gas product, the yield of H₂, CH4, CO was 2.37mmol/g, 2.04mmol/g, 25.60mmol/g respectively.By the gas mixture of carbon dioxide and water vapor as activator, under the activation temperature of 850℃, activation time of 120 min, the amount of activator 500 m L/min, the effect of CO₂/H₂ O volume ratio on properties of activated carbon and gas product composition distribution were studide. The results show that, the performance of activated carbon increased significantly when the volume ratio of CO₂/H₂ O to 7:3, the iodine adsorption value, methylene blue adsorption value and BET specific surface area were 896mg/g, 83mg/g, 835m²/g separately. In gas product, the yield of H₂, CH4, CO was 46.71mmol/g, 7.14mmol/g, 57.37mmol/g respectively.The semi coke that load different ratio of iron, molybdenum catalyst, which prepared by pyrolysis coal briquette molded from Shenfu coal powders supported iron-based catalyst（6%Fe/Al₂O₃-SiO₂） and the supported molybdenum based catalyst（10%Mo/Al₂O₃-SiO₂） in different proportions, were activated at 850℃ for 120 min with CO₂/H₂ O at volume ratio of 7:3. The effect of type of catalyst and its adding amount on performance of activated carbon and gas product composition distribution were researched. The results show that, when addition of 8% supported iron-based, molybdenum based catalyst respectively, the iodine adsorption value of activated carbon was highest, reached 813mg/g and 784mg/g respectively, methylene blue adsorption value also the highest, achieved 148mg/g and 119mg/g respectively, the total gas production were 394mmol/g and 335mmol/g respectively, the yield of H₂ were 90.32mmol/g and 77.02mmol/g respectively.XRD analysis of the semi coke and activated carbon showed that, after activation of semi coke, the disordered degree of microcrystalline structure was increased, the degree of graphitization was greatly reduced. Scanning electron microscopy analysis showed that, the semi coke surface has only a few open pore structure, while the activated carbon surface formed with a developed pore structure. The transition metal iron and molybdenum major for oxygen transfer mechanism in catalytic activation process, and mainly with the development of mesoporous. Through the thermogravimetric experiment found that, iron and molybdenum catalyst addition can significantly reduce the activation energy of gasification reaction, the gasification reaction showed a good catalytic effect.