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The present research on the complex and heterogeneous characterization of methane (CH4) adsorption in coal pores has not yet been revealed. In this article, the multifractal theory is employed to explore the complexity and heterogeneity of CH4 adsorption in coal pores. The results show that the generalized fractal dimension D(q) follows a monotonically decreasing inverse S-shape as q increases, and the multifractal singularity spectrum function f(α) displays a convex functional relationship with α, indicating the presence of multifractal characteristics of the CH4 adsorption in coal pores. As the key multifractal parameters, the generalized dimension spectrum (q ∼ D(q)) and the multifractal singularity spectrum (α ∼ f(α)) of the CH4 adsorption present a favorable quantitative relation with that of coal pores, including micropores (50 nm). This finding demonstrates that the multifractal pore structure has a controlled effect on the multifractal behavior of CH4 adsorption. This study achieves a novel characterizing method on the complexity and heterogeneity of CH4 adsorption in coal pores and reveals the mechanism of CH4 adsorption in coal pores from the multifractal perspective. The derived results display potential theoretical and application values in the synthesis of coal-based materials based on a fractal design strategy.
Feng et al. (2025) studied this question.