Fujian Normal University Made Research Progress in Separation of High-purity Ethylene with Low Energy Consumption

In July 2021, the research team of Fujian Normal University (FMU) has for the first time constructed the hydrogen‐bonded organic framework materials (HOFs)via self‐assembly by hydrogen bonding of simple organic molecules to accomplish the efficient separation of ethylene/ethane at work temperature, which would promote the practical application of HOFs in the area of industrial separation with high efficiency and low energy consumption.

The research team by using the skeleton flexibility has proposed a strategy of “gate controlled mechanism” for coordinated regulation of temperature and pressure to achieve efficient separation of ethylene from ethane.Based on the results in designing and synthesizing the novel organic small molecules, a hydrogen‐bonded organic framework material with the unique“rigid and flexible” channel structure was prepared via self‐assembly by hydrogen bonding, and the triple interpenetrating hydrogen bond network could form a channel structure for selective screening of ethylene from ethane.The gas adsorption and powder diffraction analysis data have shown that the weak non‐classical hydrogen bonds (C‐H...N) were conducive to maintaining a certain skeleton flexibility, while in the meantime the continuous π…π interactions could enhance the skeleton rigidity.

Experimental results have revealed that with an increasing temperature, the threshold pressure required for gas adsorption increases, and the co‐adsorption phenomenon is minimized at the working temperature (333K) to achieve an optimized ethylene separation effect.The single crystal structure has shown that the ethylene molecules by means of the...π interactions of weak C‐H species are adsorbed in the channels.Meanwhile,this microporous HOF material possesses excellent thermal stability and can keep the skeleton stabilized in water, strong acid, strong base, and some polar organic solvents, which can provide necessary conditions for its practical application in the gas separation and purification processes.