Sorption Performance And Modification Of Lithium Silicate Based CO₂ Adsorbent Based On Natural Ore Silicon Source

Fossil fuels such as coal and petroleum are the main energy sources used in China,and the CO₂ produced by their combustion has a great impact on global warming.Therefore,the capture and storage of CO₂ in the atmosphere is essential for climate improvement.Lithium silicate?Li₄SiO₄?adsorbents have attracted extensive attention from high-temperature solid CO₂ adsorbents because of their high adsorption capacity,good cycle stability and low adsorption temperature.The cost of preparing the Li₄SiO₄ adsorbent is higher than that of other high-temperature solid adsorbents such as CaO,so it is particularly important to study how to reduce the preparation cost of the Li₄SiO₄ adsorbent.In this paper,three kinds of widely distributed SiO₂-rich natural ore as attapulgite,pumice stone and montmorillonite are used as silicon source,and Li₄SiO₄ adsorbent is prepared by traditional solid phase reaction method with lithium hydroxide monohydrate?LiOH·H₂O?as lithium source.Since the main component of the natural ore is SiO₂,it also contains metal elements such as Mg,Al,Ca,Fe,etc.,and the presence of these metal elements has an influence on the adsorption performance of the prepared Li₄SiO₄ adsorbent.Therefore,this paper mainly explores the optimum adsorption temperature,cycle performance and migration of metal elements in ore during the preparation,adsorption and desorption of Li₄SiO₄ adsorbents.From the results of isothermal adsorption,the optimum adsorption temperature of ATB-L is 700°C;the optimum adsorption temperature of FS-L is 550°C,but the initial adsorption rate at 500°C is faster than that at 550°C;The optimum adsorption temperature for MTS-L is 500°C.From the results of the cycle test,it is known that the adsorption properties of the three adsorbents are very stable,among which FS-L has the best cycle performance,the adsorption amount is 0.1g CO₂/g adsorbent and the cycle stability is very stable,after going through 22 cycles The amount of adsorption remains at the amount of adsorption at the first cycle.It can be seen from the related characterization results that the two metal elements of Al and Mg exist in the form of LiAlSiO₄ and Li₂MgSiO₄,and the two substances do not participate in the adsorption desorption reaction.Fe exists in the form of LiFeO₂ and does not participate in the adsorption desorption reaction under the experimental temperature conditions.Ca is present in the form of CaO inside the adsorbent,and the following reaction occurs:CaO+Li₄SiO₄+CO₂?Li₂CaSiO₄+Li₂CO₃.Potassium chloride?KCl?was added to the best performance FS-L in the adsorbent prepared from three different ores to modify its adsorption capacity.The doping ratios were selected from three different mass fractions of 5,10,and 15%to investigate the effects of different doping ratios on their adsorption properties.The experimental results show that the adsorption performance of 5%KCl modified to FS-L is the best.