气体吸附法表征多孔材料的比表面积及孔结构

CHARACTERIZATION OF PORE STRUCTURE AND SPECIFIC SURFACE AREA BASED ON GAS ADSORPTION APPLIED FOR POROUS MATERIALS

气体吸附法是测量多孔材料比表面积和孔结构的常用方法。本文介绍了气体吸附法的原理及实验过程,研究了氮气和氩气对同一材料比表面积测定结果的影响,结果表明当样品的比表面积大于1m2/g时,结果较一致;但当比表面积小于1m2/g时,采用氩气所得结果较为可靠。另外,分别用氩气和氮气对不同孔径的多孔材料进行了测定,结果表明气体吸附法测量孔径的适用范围为纳米级;通过和压汞法进行比较,发现在测大孔样品时,虽然孔径无法测定,但比表面积值是可信的。最后利用吸附脱附等温线对四种典型样品的孔结构进行了分析。

Gas Adsorption is one of the most optimal theory models to express specific surface area and pore structure of porous materials.The principle and experiment process of Gas Adsorption method are introduced in the present paper and the effect of different adsorbate（N2,Ar） on the specific surface area measurated for the same sample was analysed.The results shows that the data with nitrogen gas and argon gas are close in case of the surface area less than 1m2/g and the data using argon gas is more reliable when it is more than 1m2/g.Also,the gas adsorption test was performed for the porous material with different pore size,and the result shows that this method is only applicable to nano-porous materials for the pore size characterization.Compared with mercury method,the specific surface area value is credible when large pores were tested by gas adsorption method,though this method is impossible to find pore size.Finally,the pore structure of four kinds of typical samples were analyzed based on adsorption isotherms.