Nano-pore structure of different rank coals and its effect on selective adsorption of CO2 over CH4
LIU Zhenjian
PU Chao
DU Xidong
JI Yangyang
TU Xinyu
Abstract：In the context of CO2-ECBM,studying the influence of coal's nanopore structure on the selective ad-sorption of CO2/CH4 can effectively improve the accuracy when predicting the displacement efficiency of CO2 on CH4.To study the relationship between selective adsorption of CO2 over CH4 and nano-pore structure of coal,low pressure N2/CO2 adsorption and high-pressure CO2/CH4 adsorption experiments were conducted using four coals of different rank.The nano-pore structure and adsorption properties for CO2/CH4 of the coals were quantitatively characterized.Meanwhile,the effect of pore structure on selective adsorption capacity of CO2/CH4 was analyzed.The control effect of coal pore structure on CO2/CH4 selective adsorption were discussed.The results indicate that the specific surface area and pore volume in 1-50 nm range decrease with coal rank,while the values in 0.5-1.0 nm range show an U-shaped trend with coal rank.In addition,the adsorption of CO2 and CH4 can be well described by Langmuir equa-tion.The single molecular layer saturation capacity decreases with increasing temperature.The adsorption constant of CO2 is significantly higher than that of CH4.Moreover,the selectivity coefficients of CO2/CH4 range from 3.89 to 7.97,the value of which decreases with temperature but increases with the specific surface area of micropores,indi-cating that micropore distribution is beneficial for improving the selectivity of CO2 over CH4.
Keywords：nano-pore structureselective adsorptioncoal ranklow-pressure N2/CO2 adsorptionCO2/CH4 ad-sorption testadsorption isothermLangmuir equation
Publication Date：2025-05-31
Pages：8( 69-75,85 )