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Jatropha shell preparation of activated carbon and Mechanism

Author: DuanZuoHui
Tutor: PengJinHui
School: Kunming University of Science and Technology
Course: Non-ferrous metallurgy
Keywords: Jatropha hull Activated carbon Response surface methodology Physical activation Optimum craft
CLC: TQ424.1
Type: Master's thesis
Year: 2009
Downloads: 102
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Abstract

As an effective solution to the energy crisis, biomass energy sources have aroused widespread attention of the world. As a kind of biomass source, Jatropha curcas could be used for the production of diesel oil, it distributes extensively in the southern part of China with a large quantity. The Chinese government also paid great attention on the industrial development of Jatropha curcas and listed it in the National Key Technology R&D Program for further research. However some attached product like Jatropha hull inevitably appeared in the process of the industrial development and production of Jatropah curcas, generally Jatropha hull is buried or burned down as waste, this is harmful to the environment because of its toxicity, meanwhile, there is no economic efficiency. For the long run, Jatrohpa hull is green renewable resources, if the waste Jatropha hull could be recycled and taken for utilization, we can both lower the pressure laid on the environment and add a new link to the industrial development for the preparation of diesel oil with Jatropha curcas to create bigger social economy value.In this paper, the craft for the preparation of activated carbon with physical activation process with Jatropha hull was brought out based on the review of development of biomass resources of Jatropha curcas, the comprehensive utilization and research situation of Jatropha hull. Influences of different parameters on the adsorption capacity and yield of activated carbon were studied. Optimum craft for the preparation of activated carbon was obtained by the application of Response Surface Methodology(RSM). The activated carbons prepared in optimum condition were examined by nitrogen adsorption at 77 K, the pore structures of the activated carbons were investigated. The activation mechanism was discussed too.Jatropha hull produced in YunNan Province was taken as raw materials for the preparation of activation carbon with physical activation process:(1) The optimum preparation parameters of activated carbon by conventional heating with steam as activating agent were:activation temperature of 900℃, activation time of 22min, steam flow rate of 5.5g/min. The iodine number was 950mg/g, the yield was 13.32% with the surface area and total volume of 785m2/g and 0.53ml/g respectively.(2) The optimum preparation parameters of activated carbon by conventional heating with CO2 as activating agent were:activation temperature of 950℃, activation time of 40min, CO2 flow rate of 500ml/min. The iodine number was 1008mg/g, the yield was 18.02% with the surface area and total volume of 1207m2/g and 0.86ml/g respectively.(3) The optimum preparation parameters of activated carbon by microwave heating with steam as activating agent were:activation temperature of 900℃, activation time of 19min, steam flow rate of 5g/min. The iodine number was 988mg/g, the yield was 16.56% with the surface area and total volume of 1180m2/g and 0.82ml/g respectively.(4) The optimum preparation parameters of activated carbon by microwave heating with CO2 as activating agent were:activation temperature of 900℃, activation time of 30min, CO2 flow rate of 300ml/min. The iodine number was 950mg/g, the yield was 30.60% with the surface area and total volume of 1284m2/g and 0.87ml/g respectively.(5) The iodine numbers of activated carbon prepared from steam activation were able to reach the second grade of GB/T 13803.1-1999 and GB/T 13803.2-1999; the iodine number of activated carbon prepared from conventional heating with CO2 as activating agent was able to reach the first grade of GB/T 13803.1-1999 and GB/T 13803.2-1999, the iodine numbers of activated carbon prepared from microwave heating with CO2 as activating agent was able to reach the second grade of GB/T 13803.1-1999 and GB/T 13803.2-1999.(6) The pore size distributions of activated carbons prepared at optimum conditions were analyzed through NLDFT method. The result showed that, the micro-pore content of activated carbon prepared by microwave heating was more than that obtained by conventional heating with the same activating agent. The meso-pore content of activated carbon prepared by steam activation is more than that prepared by CO2 activation with the same heating system.(7) The analysis of the activation mechanism showed that the molecule diameter of steam is bigger than CO2, the reaction velocity of steam is much quicker than CO2. The active points by microwave heating is more, so the reaction velocity by microwave heating is faster than conventional heating.

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