Multifractal Characterization of Low-temperature Nitrogen Adsorption for Pore Distribution of Coal

Abstract

In this paper, multifractal analysis from low-temperature nitrogen adsorption isotherm was employed to analyze the heterogeneity of pore distribution of low-volatile bituminous coal, and the effect of macreal composition on the distribution of pore heterogeneity was discussed. The results show that the generalized dimension Dq decrease as q increases, demonstrating a multifractal behavior of pore distribution of coal derived from low-temperature nitrogen adsorption. However, the degree of multifractality shows differences among coal with various maceral composition. In comparison of vitrinite-rich coals, the Dq values of the width of left side D-5-D0 of inertinite-rich coals decrease while the values of information dimension D1 and Hurst exponent H increase. The above results show that with the increasing inertinite, the pore structure becomes simple, the clustering of pores decreases, the pore connectivity increases, resulting in the reductionin heterogeneity of pore distribution. For the same rank coal, the D1, H and D-5-D0 are the major indexes to differentiate between heterogeneity of pore distribution of coal with different maceral composition.

Keywords

• maceral composition
• gas adsorption
• pore distributions
• heterogeneity
• multifractal characterization