热解自活化法制备生物质基微孔型活性炭（英文）

Microporous activated carbons from coconut shells produced by self-activation using the pyrolysis gases produced from them,that have an excellent electric double layer performance

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。

Coconut shell-based activated carbons were prepared by self-activation using the pyrolysis gases generated from them.The process was carried out at high temperatures in a closed reactor filled with coconut shell under a high pressure that was generated by pyrolysis gases.Results indicate that the activated carbon prepared at900for6h has a specific surface area,total pore volume,micropore percentage,iodine adsorption capacity and methylene blue adsorption capacity of1194.4m2/g,0.528cm3/g,87.8%,1280mg/g and315mg/g,respectively.When used as the electrode material of electrochemical capacitors this activated carbon exhibits a specific capacitance of258F/g,a high capacitance retention rate of97.2%after3000charge/discharge cycles and a small impedance.The water vapor and carbon dioxide generated by the pyrolysis of the coconut shell in the closed reactor act as activating agents and also increase the pressure of the reaction system.This is favorable for the activation of the formed char.This self-activation method was also used to prepare activated carbons with high adsorption capacities for iodine and methylene blue from almond stones,pecan shells and slash pine sawdust,indicating that it is a very simple,efficient,environmentally friendly and economical method for the preparation of biomass-based activated carbons for supercapacitor electrode materials and adsorption.