Fluid flow in catalytic foams accompanies with chemical reaction. so that it can considerably affect phenomena such as permeability, mass transfer, and heat transfer. Hence In the present study, the effect of chemical adsorption reaction of ammonia gas on the Cu-ZSM-5 catalyst with perfect argon gas on fluid flow and mass transfer has been investigated at different velocities of fluid in unsteady and steady states. For this purpose, the fluid flow with inlet composition containing ammonia and argon mass fraction of 0.4 and 0.6, respectively, in isotherm conditions at ambient temperature in foams with various diameter of pores 500-100 micrometer and various porosity of 96-76% was measured by computational fluid dynamics method and Simulated with finite volume method. It should be noted that the enthalpy variations of the chemical adsorption reaction are ignored in this research. The research was carried out in two parts of the mass transfer without any chemical reaction and with chemical adsorption reaction on the catalyst surface and the results were also compared. The results of the project confirms that in the condition without reaction, the fluid flow velocity is equivalent to the mass transfer coefficient. In these states, effective parameters on the velocity of fluid such as porosity distribution actually affect the mass transfer coefficient .The second part is related to the state in which adsorption reaction in catalyst foam is done. In this state, the pressure gradient and local velocity of the fluid were influenced by the changes in the concentration of foam. So that, the more the reaction improves, the more the pressure gradient decreases. Measuring the coefficient of mass transfer in foams with different geometries and inlet conditions, it was determined that this coefficient depends not only on the velocity of fluid flow, distribution of porosities and specific area, but also on active site numbers of catalyst surface and kinetic parameters of adsorption reaction. Finally, the conclusions resulted from calculating the Sherwood number in the foams with different geometries and comparing them with the Sherwood numbers provided by other researchers show a good matching. but, according to the performance index of the catalysts in different catalytic foams, it was found that foams with a higher porosity than other geometries get a higher index in applications such as catalytic beds. Keywords: Porous media, Simulation, Computational Fluid Dynamics, chemical reaction, Mass Transfere Coefficient, Catalyst