Preparation And CO₂ Adsorption Properties Of Supported Metal Oxide Adsorbents

Global warming has caused widespread concern in the international community,CO₂is the main greenhouse gas causing global warming,and the flue gas from coal-fired power plants is the main source of CO₂emissions.Carbon dioxide capture,utilization and storage（CCUS）technology is considered to be the most effective means to control carbon dioxide emissions,in which carbon dioxide capture accounts for more than 70% of the total cost.Therefore,it is very important to develop economic and reliable carbon dioxide capture technology.At present,the liquid amine absorption process is the most mature process to capture CO₂in flue gas,but it has some disadvantages,such as high energy consumption in regeneration process,serious corrosion of equipment,high steam pressure,easy solvent degradation and so on.Adsorption separation technology has the advantages of low operation cost,easy operation and low energy consumption.It is a promising CO₂ capture method to replace the traditional amine absorption method.The key is to develop efficient CO₂ adsorbent.In this paper,MgO supported adsorbents and transition metal oxide supported adsorbents were prepared by introducing metal oxides into physical adsorbents.The structure and physical properties of the adsorbents were characterized by XRD,BET and SEM.Then the adsorption capacity,adsorption selectivity,cycle stability and adsorption heat of the adsorbents for CO₂were studied by static isovolumetric method.The interaction mechanism between different transition metal oxides and CO₂ molecules was studied by using generalized gradient density functional theory.The characterization results show that the active components of the adsorbent prepared by solid-state thermal dispersion method can be well dispersed on the surface of the support.The adsorption results show that the adsorbent has high CO₂adsorption capacity,high CO₂adsorption selectivity and good cycle stability.It is a promising adsorbent to capture CO₂from mixed gas.The adsorption heat results show that the force between adsorbent and CO₂ is between physical adsorption and chemical adsorption.The configuration of transition metal oxides is optimized by using the generalized gradient density functional theory.The binding energy between transition metal oxides and CO₂molecules and the net charge number of CO₂before and after adsorption are calculated.The results show that there are four stable configurations of CO₂and Fe₂O₃.When CO₂is located at the top of OS atom in the form of C atom,and two O atoms are respectively connected with two adjacent Fe1 surface atoms,the transition metal oxides are formed One C-O bond and two Fe-O bonds,the configuration is the most stable;CO₂ and ZnO,NiO and CuO have three relatively stable adsorption configurations,CO₂ and substrate surface coordination unsaturated o,transition metal η 2-C,O bidentate adsorption,the configuration is the most stable;the binding energy between NiO and CO₂ is the largest,with the most stable configuration.