Study On Removal Of Carbon Dioxide From Coal-Fired Flue Gas By Lithium Silicate By Combustion Method

Industrial production will release a large amount of CO₂,of which power plant flue gas CO₂ emissions account for 37.5%of the total global emissions.The capture and recovery of CO₂ from power plant flue gas can not only alleviate the global greenhouse effect,but also reduce the cost of abatement by recycling by-products.Therefore,it is of great practical significance to find low-temperature,high-efficiency,stable and high-temperature CO₂ adsorption materials that can be applied to industrialization to capture and recover CO₂ from coal-fired flue gas.Lithium silicate?Li₄SiO₄?has attracted attention due to its excellent CO₂ adsorption capacity and stable cycle performance at high temperatures.In this paper,the synthesis of lithium silicate adsorbent by combustion method is proposed.The adsorption mechanism of lithium silicate is synthesized by means of changing the fuel type,ratio,pH value of the precursor and preparation process.The adsorption characteristics under the concentration of CO₂ provide a basis for improving the adsorption performance of lithium silicate under low concentration CO₂ atmosphere.The main findings are as follows:?1?The adsorption performance of lithium silicate synthesized in different proportions was tested by using citric acid and gluconic acid as fuel.The experimental results show that lithium silicate synthesized by citric acid combustion method is the highest at 15%CO₂ concentration.The adsorption capacity can be 7.3 wt%,and the maximum adsorption capacity of lithium silicate synthesized by gluconic acid combustion method is 7.51 wt%,which is more than 2.5 times of the maximum adsorption amount of lithium silicate synthesized by traditional solid phase method?2.81 wt%?;The solution was titrated to be neutral,and lithium silicate was synthesized by citric acid combustion method.The results showed that the maximum adsorption amount was 14 wt%,which was about twice that of synthetic lithium silicate in an acidic environment.?2?The neutral organic matter glucose and sucrose were used as fuel to synthesize lithium silicate.The experimental results show that the lithium silicate prepared by glucose combustion method is the largest in the volume ratio of 15%CO₂ and 85%N₂ atmosphere.The adsorption capacity is 22.21 wt%,which is more than 8 times of the adsorption amount of lithium silicate synthesized by traditional solid phase method.XRD,SEM and BET characterization test results show that the particles reach nanometer level,the pores show obvious microporous structure characteristics,and pure The phase is high,the production hole is rich,and the maximum specific surface area is 25.377 m²/g.The Na doping modification of glucose combustion method shows that the adsorption performance is the highest when n?SiO₂?:n?Na₂CO₃?=1:0.05,with Na₂CO₃ and The adsorption performance of lithium silicate prepared by NaNO₃ for Na source is better than that of lithium silicate prepared by using NaF as Na source.The maximum adsorption efficiency of lithium silicate prepared by using Na₂CO₃ as Na source can reach 94.7%.The characterization test shows that the Na-doped lithium silicate has no Na diffraction peak and the Li₄SiO₄ pure phase is high.?3?The carbonization modification of the glucose combustion method divides the combustion process into two stages.The effects of synthetic calcination temperature,fuel doping amount and carbonization temperature on the adsorption performance of lithium silicate were investigated.The results show that the adsorption performance of lithium silicate synthesized by calcination temperature of 700°C is better than that of lithium silicate synthesized by 800°C.The adsorption performance of lithium silicate synthesized by carbon dioxide modification after 2.25 times of glucose doping is synthesized.The adsorption capacity reached 24.78 wt%;the adsorption performance of the synthesized lithium silicate at the carbonization temperature of 400?reached25.96 wt%,and the adsorption performance was superior to the lithium silicate synthesized at 300?and 500?.