Preparation And Natural Gas Dehydration Performance Of Mixed Matrix Membranes Based On Metal-Organic Frameworks

The main component of raw natural gas is methane,while it still contains a significant amount of water vapor.Traditional techniques of natural gas dehydration are all suffered from high energy consumption and severe environmental pollution.Membrane-based separation technology was recognized as the most commercially promising technique,while the inherent“trade-off”effect of polymeric membranes between permeability and selectivity restricts further development at industrial scale.Mixed matrix membranes（MMMs）which combine polymer processability with the excellent gas separation performance of porous materials have great potential in natural gas dehydration.In this work,metal-organic frameworks ZIF-8 and NH₂-MIL-53（Al）were successfully prepared via the solvothermal method.Incorporating ZIF-8 and MIL-53（Al）-NH₂ filler into cellulose acetate（CA）and polyimide（PI）polymer matrix to fabricate three new types of mixed matrix membranes,which are denoted as CA/ZIF-8,Zn²⁺-CA/MIL-53（Al）-NH₂and PI/MIL-53（Al）-NH₂MMMs.Subsequently,characterization techniques including X-ray diffraction（XRD）,Scanning electron microscope（SEM）,Fourier transform infrared（FT-IR）,Thermogravimetry analysis（TGA）,Brunauer Emmett and Teller（BET）,Differential scanning calorimetry（DSC）were used for structural characterization of MMMs.Then,the natural gas dehydration performance of resultant MMMs was evaluated.The results showed that ZIF-8 and MIL-53（Al）-NH₂ could be stably dispersed in the PI and CA,and the presence of MOFs particles greatly enhanced the H₂O/CH₄ separation performance of the polymer matrix.CA/ZIF-8 MMMs with 20 wt%ZIF-8 loading,Zn²⁺-CA/MIL-53（Al）-NH₂ MMMs with 28 wt%MIL-53（Al）-NH₂ loading,PI/MIL-53（Al）-NH₂ MMMs with 33.5 wt%MIL-53（Al）-NH₂ loading demonstrated highest separation performance in each separation systems,and the H₂O/CH₄ selectivity were 422.6,433.5and 492.9,respectively.The MMMs fabricated through metal ion modification and in situ polymerization show excellent natural gas dehydration performance even under high MOFs loadings.The improved interfacial compatibility and excellent separation performance of resultant MMMs were related to the rational design of the interfacial structure.This study revealed that the rational designed MMMs fabricated in this work show a potential application for natural gas dehydration at an industrial scale.