Study on reconstruction mechanism of different solvent to surface andporosity of high rank coal

In order to discover the organic solvent effect in the new organic fracturing fluid to the high rank coal, different organic solvents were applied to the solvent extraction of the high rank coal from Changzhi, Shanxi. With the measured results of the contact angel and cryogenic nitrogen adsorption experiment, an analysis was conducted on the surface and porosity difference variation and causes of the high rank coal under the different solvent reconstruction. The study result showed that after the effect of the organic solvent, the coal-water contract angle would be obviously increased, the surface tension would remarkably decreased and the above showed that after the treatment, the hydrophobicity of the coal samples was enhanced. After the treatment of the different solvent, the BET specific surface area and the BJH specific pore volume of the coal samples would be increased in different degree. Among them, after the reconstruction with the acetone, the coal sample volume was increased in largest. The organic solvent would have the pore enlarged effect of the coal sample and the pore enlarged effect of the micro pore would be obvious. By a comparison, after the carbon disulfide, acetone and peracetic acid treated, the open pore and large pore content of the coal sample would be obviously increased and connection of the pores would be obviously improved. The tetrahydrofuran, triethylamine and ethanol solvents would have weaker improvement to the coal sample pores.