Biogasification Efficiency and Molecular Constraints of Tar-Rich Coal after Microwave Radiation

Biogasification of tar-rich coal is a promising approach to clean coal utilization. However, its low hydrocarbon generation efficiency and limited research into restrictive factors impede further advancements. This study builds on previous findings to experimentally investigate the efficiency and molecular constraints of biogasification of tar-rich coal following microwave radiation. The analysis primarily focused on the pore structure, functional group composition, and low molecular weight (LMW) compounds present in the coal samples. Results indicate that an increase in microwave radiation duration from 0 to 18 min exhibits a “wave” trend in biogasification efficiency: an initial increase, a subsequent decrease, followed by another increase, before reaching a minimum at 12 min. Principal component analysis reveals that alterations in organic matter accessibility, achieved through variations in pore structure (2–10 nm) and n-alkane content is the key factor controlling the impact of microwave radiation on biogasification efficiency. These findings shed light on the molecular constraints of microwave radiation treatment for biomethane production from tar-rich coal and propose strategies to accelerate the practical application of coalbed methane bioengineering.