Football for inspiration! This study proposes a new concept of “heat-driven molecular goalkeeper” separation

Recently, the team of Yang Weishen, researcher Yang Weishen and associate researcher Ban Yujie, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and the team of Academician Chen Xiaoming of Sun Yat-sen University proposed a new concept of “heat-driven molecular gatekeeper” separation, showing that the hydrogen/carbon dioxide separation selectivity of metal-organic framework membranes can be dynamically and reversibly modulated by temperature, and the selectivity of the membrane at 513K is increased by an order of magnitude compared with room temperature. The results were published in Science Advances.

Schematic diagram of the “heat-driven molecular goalkeeper”. Photo courtesy of Dalian Chemical Properties

High-temperature separation is essential for the chemical industry. Nanoporous molecular sieve membrane is an important separation membrane type with broad application prospects, which can realize molecular identification and sieve. However, under high temperature conditions, the thermal expansion of nanopores and the thermal activation of non-uniform molecular diffusion will reduce the intrinsic screening accuracy of molecular sieve membranes, and the separation selectivity of most molecular sieve membranes will be greatly attenuated. 

In this work, the research team took inspiration from football goalkeepers and proposed a new concept of “heat-driven molecular goalkeepers”. Through the gas-solid-thermal reaction process, the metal-organic framework precursor is induced to undergo ligand exchange, transcrystallization, and uniform encapsulation of proligand molecules in vivo and in wells. Subsequently, the team cooperated with the team of Academician Chen Xiaoming and Associate Professor Zhou Dongdong of Sun Yat-sen University to carry out systematic structural refinement and theoretical calculation, and combined with in situ experimental research, it was confirmed that the residual molecule was like the “orifice gatekeeper” of the membrane material, which was “activated” by high temperature and migrated significantly with temperature, which dynamically reshaped the membrane material screening hole window. The study also realizes the accurate interception of carbon dioxide, solves the problem of reducing the separation accuracy caused by the high-temperature activation and diffusion of carbon dioxide, and improves the hydrogen/carbon dioxide separation selectivity by an order of magnitude at the near-working temperature. The supercomputing part of this work was completed by the team of Professor Lu Yutong of the National Supercomputing Guangzhou Center of Sun Yat-sen University. 

This new separation concept expands the temperature window of molecular sieve membrane separation applications, which is of great significance for molecular sieve membrane design. (Source: Sun Danning, China Science News)

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