A two-dimensional numerical model has been established to model the sorption process inside fixed-bed adsorber. In the model, mass transfer rate, porosity distribution, nonisothermal, pressure drop, gas compression and also the dead volumes are taken into account. The model. has been applied to simulate a PSA air separation cycle for oxygen production on LiX zeolite with both 2 beds considered simultaneously, where the tube-to-particle diameter ratio (dB/dp) is 50. The results clearly show the concentration distribution and its propagation with time and a non-uniform packing induced concentration maldistribution. The two-dimensional simulation is found to be very useful for a better understanding of the dynamic adsorption and separation process in an adsorber. The results of further research are capable to guide or optimize the design of adsorber configurations.