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An ultrathin membrane for gas purification

Short-chain, organic gases are byproducts of crude oil processing in the petrochemical industry and are valuable feedstocks for plastic production. But before they can be used for this purpose, they must be purified.

In Advanced Functional Materials, Professor Zhiping Lai and his colleagues from King Abdullah University of Science and Technology report a new technique for fabricating a highly selective membrane for gas purification.

The membrane is constructed from a metal–organic framework called ZIF-8. This material contains pores that can flex when gases pass through. Due to this flexing effect, both propene and propane can pass through; however, propene diffuses through much faster than propane.

Heng-Yu Chi: Gas separation performance can be evaluated by two factors: selectivity and permeance. Selectivity is dependent on the quantity of membrane defects. Permeance is dependent on the thickness and porosity of the membrane. Generally, high permeance means low selectivity, and vice versa.

Dr. Ruicong Wei: We used an electrochemical deposition method to fabricate the separation membrane. This method allows dynamic self-healing of membrane defects. We carefully designed this electrochemical process to use a low current density that enabled membrane formation while avoiding the creation of impurities.

The membrane formed from this strategy is only a single layer of crystals thick, very pure, and has excellent porosity. As a result, the membrane has both high permeance and good selectivity.

To find out more about ZIF-8-based membranes for gas purification, please visit the Advanced Functional Materials homepage.

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