Separation Of Gas Mixture Using A ZIF-8/glycol-water Slurry By Absorption-adsorption Hybrid Method

This dissertation focuses on how to effectively capture CH₄ from the coke oven gas,coal seam gas,and separate C₃H₆ / C₂H₄ of the refinery gas.The aim is to separate the gas mixture of CH₄ / H₂,CH₄ / N₂,C₂H₄ / C₃H₆ using ZIF-8/ glycol-water slurry.Then the CH₄ can be efficiently captured,the H₂ can be enriched,and the alkene as important raw material can be recovered.This method is expected to achieve a continuous operation,and there is industrial value.The main contents of this work are as follows:（1）The separation of CH₄/H₂ and CH₄/N₂ gas mixture.Firstly,the absorption-adsorption capacity of ZIF-8/glycol-water slurry for the single-component gas could be measured.It is found that the order of sorption amount is CH₄>N₂>H₂.Then separation experiment of CH₄ / H₂,CH₄ / N₂ are carried out.It is found that the highest separation factor can reach 32.5 and 4.2 respectively.The microstructure of the slurry is observed by polarization microscopy and the existence of the liquid membrane is proved.（2）The separation of C₂H₄ / C₃H₆ gas mixture.Firstly,the absorption-adsorption capacity of ZIF-8/glycol-water slurry for the single-component gas could be measured.It is found that the sorption amount of C₃H₆ is higher than C₂H₄.Then separation experiment of C₂H₄ / C₃H₆ mixture is carried out.It is found that the highest separation factor could be achieved to 8 and the separation ability for the gas mixture could be improved with the content of glycol in the slurry system increased.（3）The investigation about the regenerability of the ZIF-8/glycol-water slurry.Repeated adsorption-desorption experiments are respectively carried out for the gas mixure of CH₄/H₂ and C₂H₄/C₃H₆.The results show that the abilities of separation and sorption of slurry system for gas mixure could be remained.Additionally,recovered ZIF-8 is characterized by X-ray diffraction（XRD）and infrared ray（IR）.It is proved that the structure of ZIF-8 is remained.These results demonstrate that the slurry system can be repeatedly used to separate the neutral mixed gases of CH₄ / H₂ and C₂H₄ / C₃H₆.But the result of the repeated experiments for the mixture of CH₄ /N₂/CO₂,which contains acid gas species,shows that the sorption ability of slurry system decreasedobviously.So the ZIF-8/glycol-water slurry system is not suitable for the separation of mixed gases containing CO₂.