Based on the above analysis, limite

Based on the above analysis, limited studies have been conducted on the differences in pore structure in low-, middle- and high-rank TDCs. In particular, we lack a comprehensive understanding of the characteristic structural features and evolution mechanisms of coal pores, including open pores and closed pores with different degrees of metamorphism and deformation, particularly the evolution law and transformation mechanism between open pores and closed pores.In this research, middle- and high-rank coal samples (Ro, max = 1.14–3.44%) with original and tectonically deformed structures were analysed by LTNA, SAXS and SEM. The pores’ structural features were investigated by analysing the distribution and variation of pore diameter, pore volume and SSA of open pores and closed pores. Moreover, differences in the pore structure were discussed through comparison with the values for low-rank tectonically deformed coals (TDCs) (Ro, max = 0.88–0.96%) reported in previous studies [44]. Based on this research, the structure feature and evolution mechanisms of coal pores (open pores and closed pores) with different metamorphism and deformation degrees were summarized comprehensively.