Preparation Of PEBA Ternary Mixed Matrix Membrane And Study On Its CO₂ Separation Performance

With the burning of fossil fuels such as crude oil and coal,the storage of such non-renewable resources has dropped sharply,and it has caused many environmental problems.In order to alleviate the fuel problem,most countries focus on the development and use of biomass energy,and biogas is one of the most widely used.However,in addition to CH₄ gas,there is a large amount of impurity gas（content of25%-50%）including CO₂ in biogas,which affects the storage of biogas and the calorific value of biogas as fuel,resulting in generally low biogas utilization.This paper is based on membrane separation technology,using attapulgite（ATP）,polyether block amide（PEBA2533）and polyethylene glycol（PEG）as materials to prepare mixed matrix membranes,which are used to separate CO₂ from biogas to purify biogas.Increase the content of CH₄.The main research work is as follows:（1）Use Materials Studio molecular simulation software to construct CO₂,CH₄,PEBA2533 models and experimental simulation systems,and use the Forceite module to optimize and kinetic calculations,and investigate the effects of different temperatures and pressures on the diffusion coefficient of CO₂ in the mixed gas in the PEBA membrane.influences.The results show that the maximum diffusion coefficient of CO₂is 18.6 at 25°C and 0.2MPa.Provides temperature and pressure guidance for experimental research.（2）Modified ATP with aminopropyltriethoxysilane（KH550）and N-aminoethyl-3aminopropylmethyldimethoxysilane（KH602）to prepare aminosilane-modified ATP,FI-IR,XRD,TG,CA were used to characterize the structure of modified ATP.The results showed that aminosilane was grafted onto ATP,and both silane coupling agents successfully modified ATP.（3）PEBA2533 is used as the polymer substrate,ATP or modified ATP is used as the filler,and the two are blended to prepare a binary mixed matrix membrane.The structure characterization and separation performance test of the mixed membrane showed that the two phases were only physically blended and had good co MPatibility;KH602 modified ATP was used as the filler particle at 25°C and 0.2MPa,and the content was PEBA The PEBA/KH602-ATP mixed matrix membrane has the best gas separation performance at 8wt%,the CO₂ permeability coefficient reaches 300.8 Barrer,and the CO₂/CH₄selectivity can reach 43.1,which is 111.4%and 102.3%higher than that of the PEBA pure membrane.（4）In order to further improve the gas separation performance of the mixed matrix membrane,PEG400 was introduced as the third component material to prepare a ternary mixed matrix membrane.The effect of different modified ATP content on the gas separation of the ternary mixed matrix membrane was investigated.The results showed that the membrane performance reached the best when the addition amount was8wt%at 25℃and 0.2MPa,and the CO₂ permeability coefficient reached 383.2Barrer,CO₂/CH₄ The selectivity can reach 55.1,which is 169.2%and 158.7%higher than that of PEBA pure membrane,and exceeds the Robeson separation upper limit revised in2008.