Modification Of Several Mofs And Their Enhanced Adsorption Performance Of Small Molecule Gases

Efficient small-molecule gas separation technology has important requirements in the petrochemical and environmental protection fields,such as the separation of small-molecule olefins and alkanes and the capture of CO₂.Therefore,the development of efficient and energy-saving small molecule gas adsorption separation technology has important needs and strategic significance.Focusing on this demand,this paper studies the adsorption and separation performance under humid conditions of small molecule gas CO₂/N₂ on MIL-100?Fe?synthesized at room temperature;the adsorption performance of propylene/propane on modified Cu-BTC is studied,and the mechanism of the enhancement of its propylene/propane adsorption performance is also discussed.The exploration of this article is of great significance for promoting the industrial application of MOFs.In this paper,RT-MIL-100?Fe?was successfully synthesized using room temperature synthesis method.The adsorption isotherms of CO₂,C₂H₄/C₂H₆ and C₃H₆/C₃H₈ were measured,and the fixed bed was used to study the CO₂ adsorption in the humid environment,and the effect of temperature on the breakthrough curves and the regeneration performance of RT-MIL-100?Fe?were also discussed.The adsorption capacities of CO₂on MIL-100?Fe?was3.42 mmol/g;the calculation showed that the IAST adsorption selectivity of C₃H₆/C₃H₈ on RT-MIL-100?Fe?was 2.2?38.5;the IAST selectivity of C₂H₄/C₂H₆ on RT-MIL-100?Fe?reached 6.6?152.3.RT-MIL-100?Fe?is ideal for ethylene/ethane separation under low pressure.The fixed bed experiment confirmed that the dynamic adsorption capacity of the material for CO₂ under wet conditions was 3 times that of the dynamic adsorption capacity under dry conditions.In this paper,Pyr@Cu-BTCs and Ura@Cu-BTCs were synthesized by a rapid synthesis method at room temperature,and the materials were characterized and tested for water vapor stability.The BET specific surface areas of these two samples were up to 1575.16 m²/g and1504.39 m²/g,respectively,which was slightly lower than 1605.34 m²/g of Cu-BTC.The infrared spectrum showed that pyrrole was successfully loaded on Cu-BTC.The water vapor stability test results showed that after the sample was exposed to humid air for 20 days,the crystal structure of Cu-BTC almost completely collapsed,while the two new materials developed were Pyr_1/3@Cu-BTC and Ura_1/3@Cu-BTC.Maintain a good crystal structure and have good water vapor stability.In this paper,the separation performance of Pyr@Cu-BTCs and Ura@Cu-BTCs materials for propylene and propane was studied,and the mechanism of the enhanced propylene propane separation on Pyr_1/3@Cu-BTC was studied using computational simulation.Pyr_1/3@Cu-BTC and Ura_1/3@Cu-BTC are materials that preferentially adsorb propylene.At298 K and 100 k Pa,the IAST selectivity of C₃H₆/C₃H₈ on Cu-BTC is 5.65,while the IAST selectivity of C₃H₆/C₃H₈ on Pyr_1/3@Cu-BTC is as high as 8.33,and the adsorption capacity of C₃H₆ and C₃H₈ reaches 7.60 mmol/g and 6.67 mmol/g,respectively.The experiments of fixed bed show that Pyr_1/3@Cu-BTC has better dynamic separation performance than Cu-BTC,and can completely separate the binary mixture of propylene and propane under normal temperature conditions.