Activated carbon monolith is widely used as adsorbent to enhance the storage capacity of natural gas

which greatly inspires the investigation on adsorption dynamics of methane on this type of adsorbents.The differential pressure permeation method was used to measure the surface diffusion coefficient.The impacts of Knudsen diffusion

viscous flow and surface diffusion on total diffusion were investigated by using the Maxwell-Stefan model

and the dependence of these impacts on temperature and pressure was also discussed.An empirical correlation was proposed to calculate the surface diffusion coefficient.In the ranges of experiment temperature and pressure

the adsorption dynamic process was dominated by surface diffusion

while Knudsen diffusion was also important at a low pressures.As the pressure increased

the surface diffusion coefficient approached a constant value

however viscous flow kept continuously rising and contributing an important part to the total flux.