Study Of The CO₂ Adsorption On Modified Metal Organic Frameworks Material MIL-101?Cr? Under Atmospheric Pressure

Burning of quantities of fossil fuels causing increasing elevated concentration of atmospheric CO₂ whose excessive emission could exacerbate the greenhouse effect,which causing global average temperature gradually increased and seriously affect the normal life of human.Therefore,the efficient CO₂ capture becomes one of the hot topics of research at home and abroad.Metal organic frameworks?MOFs?material as a class of novel porous materials with unique properties,it has great application potential in terms of gas adsorption separation result from having the advantages of large specific surface area?developed pore structure and adjustable size of aperture,etc.Using MOFs material for CO₂ capture and separation were received extensive attention from researchers.This study selects the MIL-101?Cr?as the object,a systematic study of the CO₂ adsorption properties of the before and after amino-functionalized materials at ambient temperature and pressure.The main research contents and conclusions are as follows:?1?Ethylenediamine?ED?was grafted on MIL-101?Cr?by solvothermal method,synthesized a new type of adsorbent MIL-101-ED,and characterized with XRD?N₂ adsorption-desorption?infrared and so on.Measured the CO₂ adsorption properties and CO₂/N₂ adsorption selectivity of the modification materials under 298 K and 1.01×105 Pa,and researched the effects of quantity of grafted ethylene diamine and temperature on the material structure,morphology and CO₂ adsorption performance.The results show that the CO₂ uptake capacity of ethylene diamine-modified MIL-101?Cr?materials could be 2.43 mmol/g at ambient temperature and pressure,14.6% higher than MIL-101?Cr?,CO₂/N₂ adsorption-separation coefficient increased from 11 to 17,55.6% higher than before modification.Modified materials can be completely desorption regeneration after 80 ? vacuum heating which has the very good stability of regeneration.?2?Through combination pre-modification with post synthetic amino modification functional methods,first doped with different amounts of 2-aminoterephthalic acid ligand for the synthesis of MIL-101?Cr?and get a series of different doping amounts of 2-aminoterephthalic acid ligand-modified material NH₂-MIL-101,and experiment with XRD,N₂ adsorption-desorption characterization.Measured the CO₂ adsorption isotherm and per unit specific surface area for CO₂ adsorption isotherm of the materials at 298 K and 1.01×105 Pa respectively.The results show that when the amount of doping 2-aminoterephthalic acid ligand is 75%,the CO₂ adsorption capacity and per unit specific surface area for CO₂ adsorption capacity are relatively large.?3?For further enhance the MIL-101?Cr?adsorption capacity and adsorption selectivity,this paper also studied the NH₂-MIL-101 modified with different amounts of polyethylenimine?PEI?,and measured its CO₂ adsorption isotherm at ambient temperature and pressure and different temperatures,and regeneration cycle performance of modified materials.Results show that NH₂-MIL-101 modified by PEI can significantly improve the CO₂ adsorption capacity and adsorption selectivity at ambient temperature and pressure,wherein the material for CO₂ adsorption capacity from 1.75 mmol/g before modification increased to 2.78 mmol/g,improved 58.9%,CO₂/N₂ preferential separation factor also raised from 13 to 39,more than tripled.Modified materials for CO₂ adsorption capacity up to 3.51 mmol/g at 5 0.1? MPa.And modified materials has the good regeneration performance even by five times adsorption-desorption is still consistent with initial level.