Finite difference approximation in a non-isothermal and non-adiabatic fixed bed adsorption model: an application to n-hexane

In this work, we solved the differential equations of mass and energy balance describing the n-hexane adsorption and desorption process in 5A zeolite under non-isothermal and non-adiabatic conditions. The solution provided a theoretical model that may be used to determine the significance of the mass and thermal transfer effects applied to transient adsorption. We validated numerical results with experimental data from the literature, finding the n-hexane adsorption to be exothermic. Because the diffusion in the system is fast, the breakthrough curves showed the typical form of thermal limitation. We found desorption depends on the desorbent fluid and feed rate. We evaluated the stability of the numerical method using the eigenvalues of the matrix system. Hence, the computational code developed may be used to simulate real operating conditions for the adsorption/desorption process of gases with porous adsorbents once the process parameters are known.