Study On Carbonization And Thermochemical Energy Storage Of Lithium Silicate Pellets Modified By Ball Milling And Alkali Metal Salt At High Temperature

The large amount of CO₂ emissions from fossil fuel combustion is contributing to the increasing global warming.Without effective measures to control CO₂ emissions,global temperature rise may be 2?higher than pre-industrial level.Therefore,it is urgent to study efficient CO₂ capture technology.Lithium silicate?Li₄SiO₄?is a kind of CO₂ adsorbent with good performance.The synthetic material is from a wide range of sources,the price is low,the preparation method is simple,and the cyclic adsorption stability is high.The surface of Li₄SiO₄ prepared by solid-phase synthesis method is badly sintered and has a large particle size.In the low concentration?4¹5wt.%?CO₂atmosphere of coal-fired power plants,the adsorption performance of Li₄SiO₄ is poor,so modification of Li₄SiO₄ is needed to improve its adsorption performance.Solar energy is the largest clean energy in nature.Thermochemical energy storage technology is to store/release solar energy through the reversible reaction of energy storage materials and gas.Li₄SiO₄ is a potential heat storage material,and the process of heat storage/heat release corresponds to the process of desorption/absorption of CO₂.Due to the instability and intermitteness of solar energy,Li₄SiO₄ is required to quickly absorb a large amount of CO₂ in a short time to maintain its high cyclic heat release performance.The CO₂ capture and thermochemical energy storage of coal-fired power plants are carried out in the fluidized bed.It is required that Li₄SiO₄ material not only has good adsorption performance and high heat emission,but also has certain hardness to be suitable for the fluidized bed.In this study,the composite modified Li₄SiO₄ with ball mill and doped alkali metal salt was used for granulation to prepare Li₄SiO₄ pellets with good adsorption performance in low concentration CO₂ atmosphere,high circulating heat release in thermochemical energy storage technology and certain hardness.The main research contents of this paper are as follows:?1?In solid preparation method of Li₄SiO₄ at low concentrations?15vol.%?adsorption CO₂ atmosphere,the highest adsorption quantity only 3.8wt.%,the Li₄SiO₄doped alkali metal ball grinding compound modification and granulation,choose the optimal alkali metal NaF as dopant,and optimize the concentration of NaF,preparation of adsorption ball samples reached 17.6wt.%,still can not reach the ideal adsorption effect,at last,by doping expanding agent glucose calcined reaming,preparation of porous pellet Li₄SiO₄ adsorption quantity up to 30wt.%,Close to the theoretical adsorption capacity of Li₄SiO₄?36.7wt.%?,the pellets not only have good adsorption performance,but also have a certain hardness?3.8N?,which is suitable for capturing low-concentration CO₂ in a fluidized bed.?2?According to the relationship between adsorption capacity and heat release,the higher the adsorption capacity of Li₄SiO₄,the higher the heat release.Li₄SiO₄ powder has low CO₂ adsorption and low heat release in a short time.The modified Li₄SiO₄powder doped with NaF ball mill has good cyclic adsorption performance and high cyclic heat release.Li₄SiO₄ powder and Li₄SiO₄ powder doped with NaF were mixed with 15wt.%glucose,respectively.After pelletizing,calcination and decarburization were carried out to prepare two kinds of porous Li₄SiO₄ pellets.Both of these pellets had high circulating heat release.Undoped NaF porous Li₄SiO₄ pellets release slightly higher heat,its hardness?2.6N?qualified,is an ideal thermal storage material in thermochemical energy storage technology.The paper has 32 pictures,3 Table,95 references.