The Preparation Of Two MOFs Composites And Its Adsorption Performance Toward CO₂ And Water Vapor

Energy crisis and environmental problems caused by huge consumption of fossil energy have hindered the sustainable development of human society. Adsorption is a potential technology for CO₂ capture and adsorption heat pump application, where the porous adsorbent played the key role. It is the hot spot in recent year to develop adsorbents with large adsorption capacity and high water stability while optimizing the preparation technics. This dissertation mainly involved the preparation of two novel MOFs composites, the influence of water vapor on CO₂ adsorption over MOFs, the adsorption capacity and mechanism of water vapor, ethanol on MOFs, and explored the new efficient technique to synthesis MOFs composites.In this work, a new type MIL-101@np Fe composites was prepared, and the adsorption behaviors of CO₂ in the presence of water vapor over it was studied. It was found that the surface area and pore volume decreased as the np Fe loading amount increased. The results of fixed bed experiments show that the enhancement of air flow relative humidity led to obvious decline of CO₂ working adsorption capacity on MIL-101（Cr）, by contrast, the presence of water vapor enhanced the CO₂ working adsorption capacity on MIL-101@npFe, the adsorption capacity of CO₂ on MIL-101@npFe increased by 95.5% when the relative humidity increased from 0% to 80%, this enhancement is attributed to the dissociation of H2 O and formation of new base sites on the surface of MIL-101@npFe.In this work, a new rapid room-temperature synthesis of HKUST-1@GO composites was proposed, then the composite were modified by silicohydride and its adsorption behavior toward CO₂ was investigated. The results show that the preparation time of HKUST-1@GO could be shortened from 12 h（water thermal synthesis） to 1 min at room temperature. The CO₂ adsorption capacity of HKUST-1@GO reached up to 9.02 mmol/g at 273 K, which was higher than that of original HKUST-1（8.05 mmol/g） under the same conditions. Furthermore, after silicohydride-modification, the water vapor stability of composites improved noticeably.In this work, the adsorption performance and adsorption mechanism of ethanol on MIL-101（Cr） was investigated. Results showed that adsorption capacity of MIL-101（Cr） for ethanol was up to 20.3 mmol/g at 298 K, much higher than those of some other traditional adsorbents. At low pressure, the adsorption capacity of MIL-101（Cr） for ethanol was higher than that for water vapor, which could be ascribed to the higher dipole moment and dynamic diameter of ethanol compared to water molecule. At high pressure, multilayer adsorption or cage filling occurred, and thus the molecule with big dynamic size would be filled within MOFs less in moles than that with small dynamic size due the limitation of the pore volume of MOFs.