Fractal characteristics for coal chemical structure: Principle, methodology and implication

Despite coal chemical structure's importance as the organic backbone for hydrocarbon production, the fractal characteristics for coal chemical structure remains unexplored. Therefore, this paper proposed a novel method to calculate the fractal dimension Df for coal chemical structure. The principle and methodology of the proposed method were deduced and summarized in detail. This method was applied to calculate the fractal dimension Df for the coal chemical structure from lignite to anthracite. The research results indicate that the fractal dimension Df for coal chemical structure decreases first and then increases with coalification. The turning point of the variation trend of fractal dimension Df and coalification corresponds to the second coalification jump (maximum vitrinite reflectance Ro, max = 1.30 %). This study has achieved the micro characterization on coal chemical structure at molecular scale, which has potential application value on the functional properties analysis and molecular synthesis design of coal-based material research fields.