Hydrogen bond unlocking-driven pore structure control for shifting multi-component gas separation function

Abstract

Purification of ethylene (C₂H₄) as the most extensive and output chemical, from complex multi-components is of great significance but highly challenging. Herein we demonstrate that precise pore structure tuning by controlling the network hydrogen bonds in two highly-related porous coordination networks can shift the efficient C₂H₄ separation function from C₂H₂/C₂H₄/C₂H₆ ternary mixture to CO₂/C₂H₂/C₂H₄/C₂H₆ quaternary mixture system. Single-crystal X-ray diffraction revealed that the different amino groups on the triazolate ligands resulted in the change of the hydrogen bonding in the host network, which led to changes in the pore shape and pore chemistry. Gas adsorption isotherms, adsorption kinetics and gas-loaded crystal structure analysis indicated that the coordination network Zn-fa-atz (2) weakened the affinity for three C2 hydrocarbons synchronously including C₂H₄ but enhanced the CO₂ adsorption due to the optimized CO₂-host interaction and the faster CO₂ diffusion, leading to effective C₂H₄ production from the CO₂/C₂H₂/C₂H₄/C₂H₆ mixture in one step based on the experimental and simulated breakthrough data. Moreover, it can be shaped into spherical pellets with maintained porosity and separation performance.

C₂H₄ is one of the most important chemical raw materials. Here, the authors report that tuning of pore structure shifts the multi-component gas separation function, enabling one-step production of high-purity C₂H₄ in the quaternary mixture.