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提出热解自活化制备生物质基活性炭的新方法,制备过程不添加任何活化剂。将生物质原料置于可密闭反应器,在高温高压条件下进行热解自活化反应。结果表明,椰子壳是热解自活化制备微孔型活性炭的最佳原料,选择活化温度900℃并保持6 h,制备出了具有网络状发达微孔结构的活性炭,微孔率高达87.8%,比表面积1 194.4 m~2/g,总孔容积0.528 cm~3/g,碘吸附值1 280 mg/g,亚甲基蓝吸附值315 mg/g。同时,作为电化学储能电极材料,比电容可达258 F/g,而且阻抗小,3 000次充电循环后比电容仍能保持97.2%。热解自活化机理研究表明,生物质热解过程中产生的水蒸气、二氧化碳和反应器内的空气形成了良好的活化气氛,密闭反应器内形成的自生压力促进了水蒸气/二氧化碳与固体炭的活化反应速度,明显提高了微孔率。为了验证热解自活化法对其他生物质原料的适用性,还选择了杏核、核桃壳和松木屑作为原料进行热解自活化实验,并制得了高吸附力的活性炭样品。因此,热解自活化是一种无污染、清洁方便、产品得率高的新型活化方法,可产生良好的经济和环境效益。
Proposed a new method for the preparation of biomass-based activated carbon from pyrolysis and self-activation, the preparation process does not add any activator. The biomass material placed in airtight reactor, under high temperature and pressure pyrolysis self-activation reaction. The results showed that coconut shell was the best raw material for pyrolytic self-activation preparation of microporous activated carbon, activated carbon was selected at activation temperature of 900 ℃ for 6 h, microporous structure was obtained with a microporous rate of 87.8% The specific surface area was 1 194.4 m 2 / g, the total pore volume was 0.528 cm 3 / g, the iodine adsorption value was 1280 mg / g and the methylene blue adsorption value was 315 mg / g. At the same time, as the electrode material of electrochemical energy storage, the specific capacitance can reach 258 F / g, and the impedance is small. After 3000 charge cycles, the specific capacitance can still maintain 97.2%. The mechanism of self-activation of pyrolysis shows that the steam, carbon dioxide and the air in the reactor produced during pyrolysis of biomass form a good activation atmosphere, and the autogenous pressure formed in the closed reactor promotes the interaction between water vapor / carbon dioxide and solid carbon Of the activation reaction rate, significantly increased microporosity. In order to verify the applicability of pyrolysis and self-activation method to other biomass materials, apricot, walnut shells and pine wood chips were selected as raw materials for pyrolysis and self-activation experiments, and a sample of activated carbon with high adsorption capacity was obtained. Therefore, pyrolytic self-activation is a new type of activation method that is pollution-free, easy to clean and high in product yield, which can produce good economic and environmental benefits.