Pore structure of selected Chinese coals with heating and pressurization treatments

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...

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Bibliographic Details
Published in:Science China. Earth sciences 2014-07, Vol.57 (7), p.1567-1582
Main Authors: Cai, YiDong, Liu, DaMeng, Pan, ZheJun, Yao, YanBin, Li, JunQian, Qiu, YongKai
Format: Article
Language:English
Subjects:
Adsorption
Coal
Earth and Environmental Science
Earth Sciences
Fractals
Heat conductivity
Heat treatment
Heating
High temperature
Hydrostatic pressure
Isotherms
Pore size
Pressure
Research Paper
中国
加压处理
加热
孔隙结构
小角X射线散射
扫描电子显微镜
煤级
表面分形维数
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Summary: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.
ISSN:1674-7313
1869-1897
DOI:10.1007/s11430-014-4855-y