高压氮气置换甲烷对煤基质孔隙的影响

为探究高压气体吸附-解吸试验对煤基质中孔隙发育规模和结构的影响，选取安鹤矿区鹤壁六矿二1煤层煤样进行了高压氮气置换甲烷吸附-解吸试验，采用低温液氮吸附方法分别测定了高压氮气置换甲烷前后煤的低温液氮吸附解吸曲线，利用BET、BJH和QSDFT 3种分析模型，对煤基质中1.14~300 nm的孔隙规模、分布与结构特征进行了对比分析。分析结果显示煤样的孔容、比表面积和孔隙结构在高压气体置换过程中均发生了变化，孔隙BET比表面积从12.746 0 m2/g降低到7.227 0 m2/g，总孔容从0.009 0 cm3/g降低到0.006 6 cm3/g；孔隙发育规模与孔径分布均发生明显变化，但孔隙形态基本保持不变，孔径分布的变化主要表现为微孔孔容与比表面积的降低为主，而中孔和大孔基本保持不变。 

Effect of replacing methane by high pressure nitrogen on coal matrix pore

In order to study the effect of high-pressure gas adsorption and desorption on the development scale and the structure of coal matrix pore, the experiment of isothermal adsorption-desorption of replacing methane by injecting high-pressure nitrogen was carried out on coal samples collected from No.6 coal mine of Hebi. The curves of low-temperature nitrogen adsorption and desorption of coal samples before and after methane replacement were measured by low-temperature liquid nitrogen adsorption method. The changes of pore structure characteristics and distribution of coal matrix were compared and analyzed by using three analytical models of BET, BJH and QSDFT. The analysis results show that the pore volume, the specific surface area and pore structure of coal samples have changed in the process of high-pressure gas replacement, the BET specific surface area of the pore was reduced from 12.746 0 m2/g to 7.227 0 m2/g, the total pore volume was reduced from 0.009 0 cm3/g to 0.006 6 cm3/g. The pore development scale and distribution were obviously changed, but the pore morphology was basically unchanged, and the variation of pore distribution was mainly manifested in the reduction of micropore volume and specific surface area, while the volume of mesopores and micropores kept basically unchanged.