不同孔隙孔径碳材料对甲烷的吸附特征研究

On the methane adsorption characteristic features for carbon materials in different pore sizes

为探究煤矿瓦斯气体吸附存在的孔隙孔径大小及煤矿瓦斯突出压力定为0.74 MPa的微观原因,采用计算化学材料软件Material Studio对碳材料孔隙孔径进行模型构建,通过Sorption模块计算不同碳材料孔隙孔径对甲烷的吸附情况,得到了单层和双层不同孔隙孔径碳材料对甲烷的吸附数据,然后用内插法得到0.74 MPa条件下单层和双层孔隙孔径碳材料对甲烷的吸附量。结果表明：单层和双层碳材料孔隙孔径对甲烷吸附的最佳孔径分别是10和8;0.74 MPa条件下不同孔隙孔径碳材料对甲烷的吸附量均在75%以上,对于最佳孔径甚至在90%以上。

In order to search for the optimistic pore sizes wherein the coal gas can be absorbed and why the coal gas outburst pressure has been decided at the micro level of 0. 74 MPa, we have built up a carbon material studio of the molecular fragment C51 H19 （referred to as MS）, via a software known as MS. What is more, the said Fortice MS can also be used to optimize the structure of the molecular fragment C5, H19, wherein＂ the respective interval space of layer 1 and layer 2 are supposed to be 6A , 8A, 10 A, 12 A, 14 A, 16A, 18 A, which can be deduced by framing a unit cell of the molecular fragment of carbon materials. And,afterwards, it would be possible for us to work out the methane adsorption isotherms of the carbon material in their different pore diameters by the absorption at the temperature of 298 K and the fugacity of 1 MPa. The above mentioned calculation results can be gained based on the Monte Carlo method. Furthermore, the methane adsorption data of layer 1 and layer 2 can be found through the Matlab program and the transformation fugacity into pressure. At the same time, the Origin 8. 0 software can help to plot the adsorption amount in the corresponding ratio to the pressure. As to the methane adsorption amount of layer 1 and layer 2 of the carbon material, their different pore diameters at 0. 74 MPa can also be obtained with the interpolation method. Thus, the resuits of our calculation tend to prove that the optimal pore sizes for methane adsorption of layer 1 and layer 2 of the said material should be 10 A and 8 Acorresponding to the different pore diameters, while the methane adsorption amount at 0. 74 MPa should be over 75% of the adsorption amount at 1 MPa. It can also be deduced that the optimal pore diameter of layer 1 should be going up to 89. 97%, with its best diameter being over 95%. Thus, it can be concluded that it should be a perfect method to accumulate the gas release by means of increasing the coal pore diameter to promote the coal mine gas outbursts in preventing the gas outburst. In addition, it is an innovative proposal here in the paper to establish the carbon material with different pore diameters and pore sizes of the coal mine. At the same time, the pressure of 0. 74 MPa here proposed can be recommended for the ＂coal mine safety regulations＂ from the micro-perspective with its due significance for the basic theory of coal mining gas outbursts.