In Situ ZIF-8-Coated Copper Laminate System for Fluid-Phase Adsorptive Separation

The use of structured adsorbents is emerging as a promising approach for adsorptive separation processes, and several ex situ structuring routes like extrusion, three-dimensional (3D) printing, and coating over substrates have been extensively investigated. However, in situ growth of adsorbents such as metal-organic frameworks (MOFs) on metal laminates remains underexplored. This study introduces a novel laminate system, where aluminum pieces, inspired by the "LEGO" concept, were designed through CNC milling and used to fabricate embossed/dented copper laminates. These laminates were then coated with ZIF-8 crystals (ZIF-8@Cu) via a direct in situ coating method at room temperature, resulting in a 100 microm coating. The system was assembled, packed in a custom-designed column, and evaluated for alcohol recovery from methanol/water and n-butanol/water mixtures. The ZIF-8@Cu laminates exhibited high adsorption capacities: 0.19 g_MeOH/g_ZIF-8, 0.26 g_n-BuOH/g_ZIF-8, and excellent selectivity toward alcohols (α_MeOH/H2O = 8.5; α_n-BuOH/H2O = 68). Vapor-phase experiments showed dispersive effects in the elution curve, attributed to the intrinsic properties of ZIF-8 (S-shaped equilibrium isotherm) and mass transfer limitation caused by channel nonuniformities and inlet flow maldistribution. For both separation mixtures, the laminate system was regenerated within 2 h via thermal swing adsorption (TSA), thereby exhibiting the combined benefits of microporosity, low-pressure drop, mechanical stability, and efficient heat transfer. The adsorptive properties were further highlighted in liquid-phase separation, where the laminates selectively captured n-butanol from 2.0 wt % aqueous solution and were successfully regenerated via TSA. This study provides proof of concept for the application of MOF-coated metal laminates in multiple adsorption-desorption cycles, thus highlighting their potential for process intensification.