Generalization of the adsorption process in crystalline porous materials and its application to Metal-Organic Frameworks (MOFs)

In this paper we present an approach for the generalization of adsorption of light gases in crystalline porous materials. Our approach allows the determination of gas uptake considering only geometrical constrains of the porous framework and interaction energy of the guest molecule with the framework. The derivation of this general equation for the uptake of any crystalline porous framework is presented. Based on this theory, we calculated optimal values for the adsorption enthalpy at different temperatures and pressures. We also present the use of this theory to determine the optimal linker length for a topological equivalent framework series. We validate this theoretical approach by comparing the predicted uptake to experimental values for MOF-5, MOF-14, MOF-177, MOF-200, SNU-77H and Li-metalated MOF-177 and MOF-200. We obtained the universal equation for optimal linker length given a topology of a porous framework. This work applies the general equation to Metal-Organic Frameworks (MOFs) but it can be used for other crystalline materials such as Covalent-Organic Frameworks (COFs) and Zeolitic imidazolate frameworks (ZIFs). These results will serve to design new porous materials that exhibit high net storage capacities, in particular for molecular hydrogen.