Preparation of activated carbons from corncob with large specific surface area by a variety of chemical activators and their application in gas storage
Preparation of activated carbons from corncob with large specific surface area by a variety of chemical activators and their application in gas storage
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DOI：
10.1016/j.cej.2010.06.031
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发表时间：
2010-09
影响因子：
15.1
通讯作者：
Yongzhen Sun;P. Webley
中科院分区：
文献类型：
--
作者：
Yongzhen Sun;P. Webley
以农业废弃物玉米芯为原料，采用不同的活化方法和活化剂制备活性炭。两步KOH活化法制备的炭的BET比表面积和孔容分别为3012 m2/g和1.7cm3/g。所有制备的碳显示出微孔特性，除了通过一步亚磷酸活化，表现出滞后的介孔碳制备。对不同炭的氢吸附性能进行了仔细研究。比表面积最大的微孔炭在77 K、1atm和298 K、5 MPa下的H2吸附量分别为2.0wt%和0.44wt%。基于Langmuir-Freundlich方程和Soave-Redlich-Kwong状态方程的吸附等温线模型用于确定气相逸度，提供了令人满意的高压氢数据的代表性。由Langmuir-Freundlich方程得到的表征固体表面完全覆盖的参数为9.73mmol/g或2wt%。具有最大氢吸收能力的碳仍然不能满足美国能源部6wt%的储氢目标。碳的等排吸附热为7 kJ/mol，这是典型的物理吸附特性，与文献中氢-碳相互作用的结果一致。
Activated carbons were produced from agricultural waste corncob using a variety of different activation strategies and activators. The BET specific surface area and pore volume of the carbons produced by a two-step KOH activation process were 3012m2/g and 1.7cm3/g, respectively. All carbons prepared showed a microporous character, except for that prepared by a one-step phosphorous acid activation which exhibited hysteresis of a mesoporous carbon. The hydrogen adsorption performance of the different carbons was closely investigated. The microporous carbon with the largest BET specific surface area showed H2adsorption capacities up to 2.0wt% at 77K under 1atm pressure and 0.44wt% at 298K at 5MPa. The adsorption isotherm model based on the Langmuir–Freundlich equation together with Soave–Redlich–Kwong equation of state for determination of the gas phase fugacity provided a satisfactory representation of the high pressure hydrogen data. The parameter representing full coverage of the solid surface from the Langmuir–Freundlich equation is 9.73mmol/g or 2wt% at 298K. The carbon with the largest hydrogen uptake capacity still cannot meet the US DOE target for hydrogen storage of 6wt%. The isosteric heat of adsorption of carbon was 7kJ/mol, typical of a physisorption character and in agreement with literature for the hydrogen–carbon interaction.