A grand canonical Monte Carlo (GCMC) method was carried out to simulate the adsorption of methane being a main component in natural gas on ZrO₂ pillared clay. In the simulation, wall potential model and optimized model parameters, σ_fw and ε_fw, were employed to make simulation results reflect very well the real interaction between methane molecules and inorganic layered boards in pillared clay. In the optimization of wall model parameters, firstly, positions of methane were changed systemically in montmorillonite crystal structure, and then a series of Lennard-Jones potential curves reflecting the interaction between methane molecules and layered boards were obtained; secondly, those Lennard-Jones potential curves were simulated through the least squares method, so a series of values of two cross-interaction parameters were obtained; finally, the even values of σ_fw and ε_fw were introduced into the formula of wall potential model, which was proved to be very effective because the simulation result was in good agreement with the experimental data. Based on optimized parameters, the adsorptions of methane on three different porosity ZrO₂ pillared clays (ZPC) with the layer distance of 0.64 nm at 245 K have been simulated. It was thought that the proper pressure of methane molecules adsorbed on ZPC materials was in the range 3～4 MPa, and the larger the porosity of ZPC materials, the more the amount of the methane adsorbed on ZPC materials.

Key words: Monte Carlo simulation, optimized parameter, methane, pillared clay