The Preparation Of XLi/HKUST-1 Materials And Their Performance For CO₂ Adsorption

With the continuous development of economy and industry,the problem of atmospheric purification has become one of the hotspots of global concern.Large amounts of carbon dioxide?CO₂?emissions lead to an increase in the concentration of CO₂ in the atmosphere,making it difficult for the earth to dissipate heat and increasing atmospheric temperatures,which can lead to a greenhouse effect.Excessive CO₂ in the atmosphere often cause serious harm to human health,the survival and development of living things,the corrosion of objects and the global atmospheric environment,air pollution has become an inescapable reality in the life of urban residents all over the world,so how to deal with air pollution gas efficiently and effectively is an important problem to be solved urgently.Adsorption method has the advantages of low operating cost,less energy consumption and fewer raw materials,and no two pollution.Therefore,it is of great significance to reduce atmospheric CO₂ concentration by variable pressure adsorption of materials.As a new material,the metal-organic framework material has high specific surface area,controllable pore structure and abundant active sites,compared with traditional adsorption materials,and has strong adsorption ability to CO₂.Furthermore,in order to study the mechanism of interaction between adsorbent and CO₂molecule,there are a lot of techniques that can be used to detect the adsorption mechanism,such as in situ NMR,X-ray diffraction and diffuse reflection Fourier transform infrared analysis technology.In this paper,the metal-organic framework material with better performance was synthesized by solvent thermal method,and then the alkali metal lithium was doped into the HKUST-1 material by impregnation method by HKUST-1 modification,and the xLi/HKUST-1materials with different metal doping were obtained by changing the concentration of alkali metal lithium.The effect of different alkali metals lithium doping on the adsorption properties of CO₂materials was investigated by means of a full-station gas adsorbent?3Flex?.The results show that the CO₂ adsorption performance of the material obtained when the concentration of doped alkali metal lithium is 2.0 mol/L reaches the maximum value,which is 102.6 cm³/g.Under the same conditions,the adsorption performance of the material was increased,compared to that of the parent HKUST-1 material.The structure,composition and morphology of the material before and after modification were characterized by XRD,BET,SEM,XPS and TGA.The characterization results show that the alkali metal lithium has been doped into the HKUST-1 material structure by this modification method,and the structure of the modified HKUST-1 material has been maintained and the performance has been improved.At the same time,through the doped alkali metal lithium,the thermal stability and regeneration properties of the material have not been destroyed,after 7 repeated experiments,the material still maintains more than 90%of the CO₂adsorption performance.Finally,combined with diffuse reflection Fourier transform infrared spectroscopy,the role of doped alkali metal lithium in the adsorption process of CO₂ is investigated,and the results show that the improved material properties of alkali metal lithium modification are not only attributed to the increase of metal active sites in the material structure due to the doping of lithium alkali metal,but also to the change of electron cloud arrangement and charge distribution in the material because of the doping of alkali metal lithium.