KOH和ZnCl2活化剂对苎麻秆基活性炭微观结构的影响

以废弃苎麻秆为原料,通过KOH、ZnCl2活化及直接炭化三种方式制备样品。采用扫描电镜(SEM)、N2吸附等温线和X射线衍射(XRD)对碳质材料的微观骨架、孔分布和晶体结构进行分析。结果表明,样品微观形貌呈现多孔性。炭化样中含两种孔径大小的多边形孔道结构,且被一定厚度的孔壁隔开,孔壁上含有较多未通透的孔。基于吸附等温线及BET理论,KOH和ZnCl2样品比表面积分别为1194.22 m2/g和741.9 m2/g。ZnCl2活性炭总孔容为0.38 cm3/g,平均孔径为2.408 nm,与之相比,KOH样品总孔容变为1.5倍,平均孔径达1.911 nm。XRD研究表明,正是活化反应导致材料晶型变化,添加KOH使活性炭石墨微晶形成明显乱层结构,促进了微孔和中孔的形成。

Effect of KOH and ZnCl2 Activators on Microstruture of Ramie Stalk Based Activated Carbon

Samples have been prepared via direct pyrolysis and by the means of activation methods with KOH and ZnCl2 using the discarded ramie stalk as the raw material.The SEM,nitrogen adsorption isothermal curve and XRD were applied to analyze the skeletal microstructure,pore distribution and crystallite structure of carbon materials.The results show that samples have a porous structure.Carbonized samples contain two kinds of multilateral pore channels,and the channels are partitioned by the pores walls with many non-transparent.Based on the adsorption isotherm and BET theory,the specific surface area of samples activated by KOH and ZnCl2 is 1194.22 m2/g and 741.9 m2/g,respectively.KOH-activated carbon exhibits average diameter of 1.911 nm and has a total volume of 1.5 times bigger than that of ZnCl2 of 0.38 cm3/g,and ZnCl2-activated product is of 2.408 nm in average pore size.X-ray diffraction studies show that activation reaction results in changes in crystal form.With the addition of KOH,the graphite crystallite of activated carbon form obvious turbostratic structure and the development of micropores and mespores is promoted.