Improved analytic methods for coal surface area and pore size distribution determination using 77 K nitrogen adsorption experiment  

作　　者：Wang Gongda Wang Kai Ren Tingxiang 

机构地区：[1]Faculty of Resource and Safety Engineering, China University of Mining and Technology [2]School of Civil, Mining and Environmental Engineering, University of Wollongong

出　　处：《International Journal of Mining Science and Technology》2014年第3期329-334,共6页矿业科学技术学报（英文版）

基　　金：the China Scholarship Council and the Natural Science Foundation of China (No. 51174212)

摘　　要：77 K nitrogen adsorption was the most widely used technique for determining surface area and pore size distribution of coal. Brunauer–Emmett–Teller(BET) and Barrett–Joyner–Halenda(BJH) model are commonly used analytic methods for adsorption/desorption isotherm. A Chinese anthracite coal is tested in this study using an improved experimental method and adsorption isotherm analyzed by three adsorption mechanisms at different relative pressure stages. The result shows that the micropore filling adsorption predominates at the relative pressure stage from 6.8E 7 to 9E 3. Theoretically, BET and BJH model are not appropriate for analyzing coal samples which contain micropores. Two new analytic procedures for coal surface area and pore size distribution calculation are developed in this work. The results show that BET model underestimates surface area, and micropores smaller than 1.751 nm account for 35.5% of the total pore volume and 74.2% of the total surface area. The investigation of surface area and pore size distribution by incorporating the influence of micropore is significant for understanding adsorption mechanism of methane and carbon dioxide in coal.77 K nitrogen adsorption was the most widely used technique for determining surface area and pore size distribution of coal. Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） model are com-monly used analytic methods for adsorption/desorption isotherm. A Chinese anthracite coal is tested in this study using an improved experimental method and adsorption isotherm analyzed by three adsorp-tion mechanisms at different relative pressure stages. The result shows that the micropore filling adsorp-tion predominates at the relative pressure stage from 6.8E？7 to 9E？3. Theoretically, BET and BJH model are not appropriate for analyzing coal samples which contain micropores. Two new analytic procedures for coal surface area and pore size distribution calculation are developed in this work. The results show that BET model underestimates surface area, and micropores smaller than 1.751 nm account for 35.5%of the total pore volume and 74.2%of the total surface area. The investigation of surface area and pore size distribution by incorporating the influence of micropore is significant for understanding adsorption mechanism of methane and carbon dioxide in coal.

关 键 词：77 K nitrogen adsorption BET model BJH model D-A model Langmuir model 

分 类 号：TQ533[化学工程—煤化学工程] O647.3[理学—物理化学]