Preparation Of Two Novel MOF/Graphite Oxide Composites And Its Adsorption Performance For H₂O And Ethanol Adsorption

This work is mainly focused on the preparation of a novel MOF/graphite oxide composite and its adsorption performance toward water vapor and ethanol for dehumidification and adsorption heat pump.In order to further improve the adsorptive capacity of MOFs to water vapor and ethanol,a new metal organic framework / oxidized graphite composites?MOF@GO?composites were prepared.The rapid room temperature synthesis was also stuied to reduce the reaction time and energy consumption of MOFs synthesis method.This work has great scientific research value and practical significance.In this work,the MIL-101 @ GO composite was prepared and its water vapor adsorption performance was investigated.The results show that the saturated adsorption capacity of water vapor in MIL-101 @ GO composites was 1.58 g/g at 298 K,which is nearly 30% higher than that of MIL-101.MIL-101@GO exhibited a fast adsorption rate of water vapor,and the diffusion coefficient of water vapor within the composite is 0.133-4.485×10-10 cm2/s at 298-313 K.After six cycles of adsorption-desorption,the desorption efficiency of water vapor on the composite reached as high as 94%,showing excellent regeneration performance and stability.The adsorption behaviors of water vapor on MIL-101@GO composite was studied and its dehumidification performance was tested.The results show that the modified DO-DO model can well describe the adsorption mechanism of water molecules on MIL-101@GO composite.Under high humidity?RH=50%,90%?,the dehumidification capacity of MIL-101@GO was 1.31 g/g and 1.42 g/g,respectively.In addition,MIL-101@GO showed good thermal desorption properties.When the desorption temperature was 58.9 ?,the desorption rate of water vapor on the composites could reach 80%.The adsorption properties of ethanol on MIL-101@GO composite and their performance in adsorption heat pump applications were investigated.The results showed that the ethanol adsorption capacity of MIL-101@GO reached 23 mmol/g at 293 K,and the ethanol adsorption capacity was mainly influenced by its pore volume.The working adsorption capacity of MIL-101@GO for ethanol vapor can reach 11.2 mmol/g at Td =390 K and the working efficiency can reach 0.68 at Td <350 K under refrigeration conditions.In the heat pump and ice-working conditions,MIL-100 showed a high adsorption capacity and work efficiency,reaching 1.2 and 0.6,respectively.The Cu-BTC@GO composites was prepared using a rapid room synthesis method and its properties in adsorption refrigeration was also studied.The results show that the synthesis of Cu-BTC@GO composites can be completed within 1 min at room temperature.The adsorption capacity of the composite was 13.60 mmol/g,which was 16% higher than Cu-BTC.The working adsorption capacity and COPc of Cu-BTC@GO were increased by 5.8-17.4% compared with Cu-BTC in the adsorption refrigeration applications.The ethanol/CO₂ separation performance of Cu-BTC@GO composite was investigated by IAST theory.The results show that the isosteric heat of ethanol adsorption on Cu-BTC@GO composite was slightly higher than that on Cu-BTC,indicating that the addition of GO can increase the electrostatic force and dispersion force between the composites and ethanol molecules.DSLF model can well fit the ethanol and CO₂ adsorption isotherms of the material.The ethanol/CO₂ adsorption selectivity of Cu-BTC@GO was significantly higher than that of Cu-BTC.At 10 kPa,the ethanol/CO₂ adsorption selectivity of Cu-BTC@GO was up to 383,which is 40% higher than that of Cu-BTC.