Kinetic fitting of methane adsorption rate and its influencing factors

Abstract

In order to reveal the mechanism of the influence of coal matrix pores on methane adsorption rate, based on the high-pressure methane isothermal adsorption experiment of coal samples with different pore structures, the desorption law of methane in coal and its internal relationship with pore structure were studied by analyzing the change of methane adsorption amount at a single pressure point over time. Bangham kinetic model was used to fit the adsorption process, and constants representing the adsorption rate were obtained. The following understandings were obtained: (1) With the decrease of particle size, the adsorption equilibrium time is shorter, small particle size samples often have more complex pore structure, which makes the adsorption reaction between gas-solid interface more active, but the particle size itself cannot increase or reduce the size of the accumulated adsorption amount at the equilibrium, it only changes the length of time required to reach the adsorption equilibrium. (2) With the increase of the mesh number, the adsorption rate also increases, but the higher the coal rank, the greater the adsorption rate growth rate.