磷酸活化汉麻布活性炭纤维的孔结构

以汉麻布为原料,采用磷酸活化法制备了汉麻布活性炭纤维,并利用低温氮气吸附和密度泛函理论(DFT)对样品的孔结构进行了分析。结果表明,随着活化温度的升高,磷酸活化的汉麻布活性炭纤维的BET比表面积和总孔容都呈现先增大后减小的变化趋势。不同方法计算得到的样品比表面积值呈相同的变化规律。样品的孔分布集中在2 nm以下的微孔范围内,既有极微孔又有超微孔,只有少量中孔,基本没有大孔。所有样品的孔径在微孔范围内都呈现多峰分布,孔径≤1 nm和1~2 nm的范围内分别都出现了2个峰值孔径。微孔孔容基本上随活化温度的升高而增加,而中孔孔容的数值则整体上变化不大。样品表面能量分布较宽,并呈现有多个不连续峰值的多峰分布,宽的孔径分布导致宽的表面能量分布和较多的能量峰值,并使吸附位的种类也随之增多。

Pore structure of the hemp cloth activated carbon fibers activated by phosphoric acid

Hemp cloth activated carbon fibers have been prepared using an H3PO4 activation method. The porous structure of the resulting samples was characterized by N2 adsorption and analyzed by the DFT method. The BET specific surface area and total pore volume of the hemp cloth activated carbon fiber initially increased with increasing temperature and subsequently decreased. The specific surface areas calculated by different methods showed the same variation with temperature. The pore size of the samples had a narrow distribution range, mainly within the 2nm micropore region. The samples possessed a reasonable amount of micropores and a small fraction of mesopores,but no macropores. All the samples exhibited a muhimodal pore size distribution with two maxima having pore size ≤1nm and two maxima in the 1-2nm micropore region. The micropore volume increased with increasing temperature, while the mesopore volume showed little change. The samples had a wide surface energy distribution and showed discrete multiple peaks. Wider pore size distributions led to wider surface energy distributions, more peaks in the energy distribution curves and an increasing variety of adsorption sites.