Pore structure of selected Chinese coals with heating and pressurization treatments  

作　　者：CAI YiDong LIU DaMeng PAN ZheJun YAO YanBin LI JunQian QIU YongKai 

机构地区：[1]Coal Reservoir Laboratory, National Engineering Research Center of ,CBM Development & Utilization, China University of Geosciences [2]CSIRO Earth Science and Resource Engineering, Ian Wark Laboratory

出　　处：《Science China Earth Sciences》2014年第7期1567-1582,共16页中国科学（地球科学英文版）

基　　金：National Major Research Program for Science and Technology of China (Grant No. 2011ZX05034-01)

摘　　要：Pore structure of Chinese coals with heating and pressurization treatments was studied using small angle X-ray scattering （SAXS）, N2 adsorption/desorption isotherms and scanning electron microscope （SEM）. SAXS was performed for some sam- ples after heat treatment at seven elevated temperatures from 25 to 250℃ at 0 MPa and for other samples with hydrostatic pressure treatment at 0, 5, 10, 15 and 20 MPa at the room temperature. The results show that N2 adsorption isotherm together with SAXS could be a comprehensive method to evaluate the pore shape and the pore size distribution： the pore shapes are generally spherical for low rank coal and they are mainly ellipsoidal for high rank coal. All these measurements were then interpreted using the fractal theory to reveal relationship between surface fractals and coal rank, and the evolution of surface fractals under heating and pressurization treatments. The results show that surface fractal dimension （Ds） changes with different treating temperature and pressure and maximum vitrinite reflectance （Ro,m）. Especially in the bituminous stage, Ds shows an increasing trend with Ro,m under varied temperatures. Moreover, Ds shows an increasing trend with increasing temperature before 200℃, and a decreasing trend after 200℃. Furthermore, the results show that Ds has a more complex relationship with Ro.m under varied treating temperature than that under varied treating pressure.Pore structure of Chinese coals with heating and pressurization treatments was studied using small angle X-ray scattering(SAXS),N2adsorption/desorption isotherms and scanning electron microscope(SEM).SAXS was performed for some samples after heat treatment at seven elevated temperatures from 25 to 250°C at 0 MPa and for other samples with hydrostatic pressure treatment at 0,5,10,15 and 20 MPa at the room temperature.The results show that N2adsorption isotherm together with SAXS could be a comprehensive method to evaluate the pore shape and the pore size distribution:the pore shapes are generally spherical for low rank coal and they are mainly ellipsoidal for high rank coal.All these measurements were then interpreted using the fractal theory to reveal relationship between surface fractals and coal rank,and the evolution of surface fractals under heating and pressurization treatments.The results show that surface fractal dimension(Ds)changes with different treating temperature and pressure and maximum vitrinite reflectance(Ro,m).Especially in the bituminous stage,Ds shows an increasing trend with Ro,m under varied temperatures.Moreover,Ds shows an increasing trend with increasing temperature before 200°C,and a decreasing trend after 200°C.Furthermore,the results show that Ds has a more complex relationship with Ro,m under varied treating temperature than that under varied treating pressure.

关 键 词：SAXS pore structure COALS heating and pressurization treatment surface fractal 

分 类 号：P618.11[天文地球—矿床学]