Mixed Matrix Membranes Based On The Polymers Of Intrinsic Microporosity PIMs:Preparation And Gas Separation Performance Studies

Despite the impressive production capacity of renewable energy sources around the world,the global concentration of carbon dioxide continues to rise.There is therefore an urgent need for an efficient and green carbon capture,utilisation and storage technology to reduce the amount of CO₂ entering the atmosphere.Membrane gas separation technology is one of the most promising gas separation technologies available and has a positive effect in terms of simplifying operational processes and reducing separation costs.It is the core of membrane gas separation technology and the demand for efficient separation membrane materials is increasing.In recent years,there has been a surge in research into new membrane materials,with a focus on achieving cost-effective CO₂ separation.the Polymers of intrinsic microporosity（PIM-1）,a glassy polymer with high free volume,have attracted much attention for gas separation,organic solvent nanofiltration and organic permeation vapourisation.This paper focuses on the microstructural modulation of PIM-1gas hybrid matrix membranes,specifically as follows:（1）Synthetic metal-organic backbone（UiO-66-NH₂）doped into the Polymers of intrinsic microporosity PIM-1 to prepare mixed matrix membranes（MMMs）.UiO-66-NH₂is an emerging MOF with special properties that distinguish it from ordinary inorganic filler molecules due to its inherent amino functional group,UiO-66-NH₂ has special pro-CO₂ properties and CO₂/N₂ separation properties.In addition,the microporous structure of UiO-66-NH₂ facilitates the enhancement of CO₂ permeability and CO₂/N₂ selectivity of the membrane.The MMMs were characterised using TGA,XRD,FT-IR,SEM,and N₂adsorption and desorption methods.The results showed that the PIM-1/UiO-66-NH₂ mixed matrix membranes loaded with 15 wt%UiO-66-NH₂ performed better compared to the pure PIM-1 membranes:the CO₂ permeability was 11735 Barrer and the CO₂/N₂selectivity was 15.（2）A new MOF@GO composite was synthesized by growing UiO-66-NH₂ in situ on the surface of graphene oxide（GO）,and the composite UiO-66-NH₂@GO was doped into PIM-1 to prepare MMMs.SEM analysis revealed that the UiO-66-NH₂@GO composite had a homogeneous structure with no obvious defects at the interface,and the PIM-1polymer chains were compatible with the UiO-66-NH₂@GO composite.The results show that the PIM/UiO-66-NH₂@GO mixed matrix membranes synthesised in this experiment have higher CO₂ permeability and CO₂/N₂ selectivity compared to pure PIM-1 membrane and PIM-1/UiO-66-NH₂ mixed matrix membranes.The PIM/UiO-66-NH₂@GO membrane with a 15 wt%loading of UiO-66-NH₂@GO achieved a CO₂ permeability of 11829Barrer and a CO₂/N₂ selectivity of approximately 24,which exceeded the Robeson upper limit of 2008.Thus,the PIM/UiO-66-NH₂@GO mixed matrix membrane balanced good gas permeability and gas separation properties.This indicates the potential of preparing UiO-66-NH₂@GO composites with decorated polymer molecular chains in improving the performance of mixed matrix membranes.