Biogasifi cation of tar-rich coal is a promising approach to clean coal utilization. However, its low hydrocarbon generation 

effi ciency and limited research into restrictive factors impede further advancements. This study builds on previous fi ndings 

to experimentally investigate the effi ciency and molecular constraints of biogasifi cation 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 biogasifi cation effi ciency: 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 biogasifi cation effi ciency. These fi ndings 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.