ZSM-5@MOF-199 core-shell composite adsorbent: Rapid ambient synthesis and CO/CO2 adsorption

Abstract

Using a hydroxy double salt intermediate, we demonstrated rapid room temperature fabrication of ZSM-5@MOF-199 core–shell sorbents. Copper chloride was compatible with the ZnO-assisted MOF growth scheme. The structural and chemical properties of the composite were fine-tuned through either the core or the shell modification, targeting a superior adsorption capacity for CO and CO2 compared to parent adsorbents. For example, the Na2S2O3-assisted MOF-199 shell reduction enriched surface Cu+ and enhanced CO adsorption capacity. Modulating the zeolite core to protonic hierarchical ZSM-5 (HZSM-5) increased CO and CO2 uptake by 20 % and 28 %, respectively. The isosteric heat of adsorption revealed that the HZSM-5 core altered surface electronic properties and influenced the CO2 adsorption performance. Thermodynamic analysis indicated that the adsorption processes involved a combination of physisorption and electrostatic interactions with an ordered arrangement of adsorbates. The core–shell sorbent can be easily tuned for selective separation of CO and CO2.