【Frontiers in HaiChuan Chemical Technology】Dalian Institute of Chemical Physics develops sponge-like metal-organic framework composite membranes for hydrogen/light hydrocarbon separation

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Recently, researchers such as Researcher Yang Weishen and Researcher Ban Yujie from the Research Group on Inorganic Membranes and New Catalytic Materials (Group 504) of our National Key Laboratory of Energy Catalytic Conversion have assembled sponge-like metal-organic framework structures on the surface of ultra-thin polymer membranes, enabling the separation of hydrogen (H2) from various light hydrocarbons. This approach provides a new strategy for the recovery of hydrogen resources from refinery exhaust gases and for reducing emissions of light hydrocarbons. The emissions from the petrochemical industry often contain by-product hydrogen and various light hydrocarbons (C1-C4), and their efficient separation holds significance both economically and environmentally. There is a restrictive relationship between the permeability and selectivity of traditional polymer membranes. For example, cross-linked silicone rubber membranes have a large free volume and high gas permeability, but their selectivity for the separation of H2/light hydrocarbons is limited. In this work, to improve membrane separation performance, the researchers first grafted siloxane-containing groups onto the surface of metal-organic framework ZIF-8 nanoparticles through coordination chemistry, endowing them with the ability to couple with silicone rubber membranes. Subsequently, the researchers spin-coated nanoparticles onto the surface of an incompletely cured active ultra-thin polysiloxane film (with a thickness of about 10 nm). By taking advantage of the combined effect of the radial centrifugal force during coating and the normal chemical pinning force between ZIF-8 and the polymer, a ZIF-8 functional layer with a sponge-like network structure (with a thickness of about 125 nm) was formed on the surface of the polymer film. This structure resembles a molecular “labyrinth,” and the repeated adsorption-desorption process of light hydrocarbons within it delays transmembrane transport, thereby enhancing the selectivity for H2/light hydrocarbon separation. This membrane exhibits good operational stability; in the separation of simulated industrial exhaust gases, it can concentrate 10% hydrogen to 83%, while reducing the emissions of C1-C4 light hydrocarbons by 78%.