Effect of Zeolitic Imidazolate Framework Topology on the Purification of Hydrogen from Coke Oven Gas

This work aims to shed light on the performance of zeoliticimidazolateframeworks for hydrogen purification from coke oven gases (COG). Usingmolecular simulation, we model COG as a mixture of six gases and studythe effect of ZIF topology on the separation performance. To do this,we compare similar structures, e.g., ZIF-8 and ZIF-11,and focus on obtaining information that explains why they behave differentlywhile being so similar. Simulation results show that the structurewith the smallest pore size best separates hydrogen from carbon monoxideand nonpolar molecules. The adsorption of carbon dioxide is also stronglyaffected by the polarizability of the structure. However, the adsorptionof the other components (methane, carbon monoxide, nitrogen, and oxygen)is strongly dependent on their pore size. We also provide molecularinformation on the effect of phase transition on hydrogen purificationusing ZIF-7 as an example, which drastically changes the pore volumeof the structure when it changes phase. These findings will help toselect high-performance ZIFs for adsorption- or screening-based hydrogenpurification. The adsorption of coke ovengas in various ZIF materialsis simulated with a new force field for hydrogen stream purification.