Zeolitic imidazolate framework 8 incorporated dual layer hollow fiber membrane for natural gas purification

Abstract

The main purpose of this work was studied the effect of ZIF-8 loading on the physical and chemical properties of dual-layer hollow fiber (DLHF) mixed matrix membranes (MMMs). In addition, the effect of the outer dope extrusion rate (DER) of the spinning on the selective layer thickness of the DLHF membrane was investigated. Finally, the gas separation performance of the coated DLHF membranes under different ZIF-8 loading and outer DER was evaluated. The recipe for the prepared DLHF membrane is: polysulfone (PSf) as polymer, N, N-dimethylacetamide (DMAc) and tetrahydrofuran (THF) as solvents, and at the same time, the metal organic framework (MOF) ZIF-8 Only added to the outer solution. Then, the solution was co-extruded through triple orifice spinneret in order form dual layer structure of membrane, where the inner layer was consists of pure PSf and the outer layer were the PSf and ZIF-8. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM) were used to analyse the ZIF-8 material and to detect DLHF membranes. The main findings that obtained from this research are as below: (1) Zeolite imidazole framework8 (ZIF-8) nanoparticles were successfully synthesized in aqueous solution with a particle size of 86.25 nm. (2) Successfully prepared DLHF membrane with high heat resistance, good chemical stability and good interaction between polymer PSf and filler ZIF-8. (3) The optimal loading of ZIF-8 was 0.5wt%, and the CO2 permeability increased dramatically by 61.19% compared to the neat membrane, and the selectivity of CO2/CH4 also improved significantly by 94.46%. (4) The experiment further concluded that when the outer DER was 1 ml/min, the prepared membrane was thin and no defects on the top skin layer. The good combination of ZIF-8 and PSf substrates and the appropriate outer DER explain the application and significance of the novel DLHF membrane.