Study On Preparation And CO₂ Adsorption Mechanism Of CO₂ Adsorption Materials

Environmental problems such as the greenhouse effect caused by the random emission of carbon dioxide have attracted wide attention.The amount of CO₂ emission from thermal power plant remains high,which become the main source of anthropogenic CO₂ emission.So controlling and reducing CO₂ emission from thermal power plant can effectively relieve the increase of atmospheric CO₂ concentration.At present,the amine solution absorption method is the most widely used and mature capture technology in the flue gas of thermal power plant.But the equipments are corroded easily by the amine solution,and the absorber is easy to volatilize.Besides,the amine solution is not only low efficiency of regeneration,but also large energy consumption of regeneration.After long-term exploration of some researchers,this problem was effectively solved by solid amine adsorbents.The methods of prepare the solid amine adsorbent mainly include grafting method and impregnation method.The adsorbent prepared by grafting method has a better amine dispersion and thermal stability.Due to the little number of the grafted amine group and consumption of a portion of the amine groups,the CO₂ adsorption capacity is poor.The impregnation method is simple and feasible,but the organic amines are easy to agglomerate and volatilize.A series of solid amine adsorbents were prepared by coordination method and the template method,which solved the above-mentioned challenges.The main research conclusions are as follows.1 A series of solid amine adsorption materials were prepared by three different preparation methods of direct impregnation,acidification impregnation and coordinationusing with tetraethylene pentamine?TEPA?as modifier,polystyrene strong acid ion exchange resin?D001?as carrier.?FT-IR?Fourier transform infrared spectroscopy,?TGA?thermogravimetric analysis and N₂ adsorption/desorption were used to characterize the adsorption materials.In a fixed-bed reactor,the effect of adsorbing material CO₂ adsorption on TEPA loading and other factors was investigated.The results showed that the solid state amine adsorbent prepared by the coordination method had better dispersibility and stability,and the CO₂ adsorption achieved 4 mmol·g^-1 at an adsorption temperature of 65°C,a TEPA loading of 40%,and an inlet flow of 40 mL·min^-1.After 10 cycles of absorption and desorption cycle under optimal conditions,the maximum adsorption capacity can still reach 96.02%of the first time.Thermodynamics and kinetics studies have been carried out,showing that the adsorption of CO₂ by the adsorbent is a result of physical adsorption and chemical adsorption.2 A series of solid amine adsorbents were prepared by the template method with ion exchange resin?D001?as carrier and polyethyleneimine?PEI?as modifier.The absorbents were characterized by?EDS?energy disperse spectroscopy and?SEM?scanning electron microscope.The effects of PEI loading,adsorption temperature and influent velocities on CO₂ adsorption capacity in a fixed bed reactor were investigated.The results show that the solid amine adsorbent prepared by the template method had a better PEI dispersion,stability and CO₂ adsorption capacity.The maximum CO₂adsorption capacity was 3.98 mmol·g^-1 when PEI loading was 30%,the adsorption temperature was 65°C and the influent velocity was 40 mL·min^-1.After 10 cycles of absorption and desorption cycling under optimal conditions,the maximum adsorption capacity can still reach 90.50%of the first time.The adsorption mechanism study results show that the adsorption of CO₂ by the adsorbent is the result of physical adsorption and chemical adsorption.The CO₂ adsorption process includes two stages of rapid adsorption and slow equilibrium,and the internal diffusion is the control step of CO₂ adsorption.