Deep coal seams with high gas content are important for coalbed methane exploration. Researchers studied coal samples from different depths in China to understand how pore structure affects methane adsorption. They found that as coal rank increases, moisture and volatile content decrease, while fixed carbon content increases. Pore volume and surface area decrease rapidly at first, then more slowly, with an increase in coal rank. The percentage of micropores increases throughout the process. The fractal features of nanoscale pores change with coal rank, indicating simpler surfaces with higher coalification. Gas adsorption capacity initially decreases slightly, then increases with coal rank.