电化学改性对贫煤瓦斯吸附解吸特性的影响

Influence of Electrochemical Modification on Adsorption and Desorption Characteristics of Lean Coal Gas

电化学方法应用于强化煤层瓦斯抽采的效果主要取决于工程设计与参数选取的合理性。采用实验室实验的方法,用H2SO4、Na2SO4和NaOH 3种电解液分别对贫煤进行电化学改性,对改性前后煤样的瓦斯吸附解吸特性进行了测试,并通过低温液氮吸附测试和红外光谱测试分析了改性对贫煤煤样孔隙结构和表面基团的改变。结果表明:未改性煤样的饱和吸附量为30.03 mL/g,Langmuir压力为0.88 MPa,最终解吸率为83.20%;经H2SO4、Na2SO4和NaOH 3种电解液电化学改性后,煤样的饱和吸附量分别为23.70、26.67、32.79 mL/g,煤样的Langmuir压力分别为1.15、1.05、0.80 MPa,煤样的最终解吸率分别为90.10%、87.84%和81.71%;用H2SO4电解液电化学改性后的贫煤,比表面积最小,平均孔径最大,含氧官能团数量最多,故抑制瓦斯吸附、强化瓦斯解吸的效果最好。

The application effect of electrochemical method to enhance gas drainage in coal seam mainly depends on the rationality of engineering design and parameter selection.In this paper,the method of laboratory experiment is used to electrochemically modify the lean coal with H2 SO4,Na2 SO4 and NaOH.The gas adsorption and desorption characteristics of the coal samples before and after modification are tested.The changes of pore structure and surface group of the lean coal samples after modification are analyzed by the low temperature liquid nitrogen adsorption test and infrared spectrum test.The results show that the saturated adsorption capacity of the unmodified coal sample is 30.03 mL/g,the Langmuir pressure of the unmodified coal sample is 0.88 MPa,and the final desorption rate of unmodified coal sample is 83.20%;after the electrochemical modification of H2 SO4,Na2 SO4 and NaOH,the saturated adsorption capacity of the coal sample is 23.70 mL/g,26.67 mL/g,32.79 mL/g,respectively;the Langmuir pressure of the coal sample is 1.15 MPa,1.05 MPa,0.80 MPa,respectively,and the final desorption rate of coal sample is 90.10%,87.84%and 81.71%,respectively;the lean coal after electrochemical modification of H2 SO4 electrolyte has the smallest specific surface area,the largest average pore diameter and the largest number of oxygen functional groups,so the effect of inhibiting gas adsorption and strengthening gas desorption is the best.