Synthesis Of Lithium Silicate High-temperature CO₂ Sorption Materials From The Sediment Of Dianchi Lake And Its Properties

The flue gas of traditional thermal power plant is the main source of CO₂ emission.Therefore,an effective method to capture CO₂ from industrial flue gas has become an important research topic.The temperature of flue gases after combustion of fossil fuel usually ranges from 400 to 600°C,reducing the flue gas temperature to separate CO₂will result in energy wasted for the power plant and heavy equipment investment.Therefore,exploring the high-temperature CO₂sorption material has great industrial value.Lithium silicate?Li₄Si O₄?is one of the most effective high temperature CO₂ solid sorbents.In this paper,the sediment of Dianchi Lake was used as silicon source to synthesize Li₄Si O₄-based high-temperature CO₂ sorbent,and its CO₂ sorption performance and mechanism were preliminarily investigated.The specific work is as follows:6 M different volume ratios of HCl and HNO₃ are used for this treatment of sediment,and Li₄Si O₄ sorbent was synthesized by solid-state method.Under the optimal conditions,the CO₂ sorption capacity was reached 27.93 wt%.The cyclic properties of Li₄Si O₄ sorbent were investigated by means of temperature swing sorption?TSA?and pressure swing sorption?PSA?.The results showed that after 22 sorption-desorption cycles,Li₄Si O₄ sorbent had excellent cycling performance under both TSA and PSA process.With the increase of cycle times,the sorption efficiency was increased?test temperature was 700 ^oC?.Different concentrations of citric acid?C₆H₈O₇?were used as acid treatment solution to pretreat sediment,and Li₄Si O₄ sorbent was synthesized by solid-state method.Under the optimal conditions,the CO₂ sorption capacity could reach31.37 wt%.The sorption-desorption cycle performance was also systematically investigated.The results showed that the cyclic stability of Li₄Si O₄ sorbent synthesized from C₆H₈O₇ treated sediment was worse than that synthesized from HCl/HNO₃ treated sediment.Li₄Si O₄ sorbent has been widely studied in the field of CO₂ sorption;however,the CO₂ concentration of flue gas outlet is relatively low in the actual industrial application.Therefore,the sorption performance of Li₄Si O₄ sorbent under different CO₂ partial pressures was systematically investigated,and its CO₂ sorption capacity was improved by doping alkali metal carbonate?K₂CO₃?.The results showed that the CO₂ sorption capacity of Li₄Si O₄ under 20 vol%and 50 vol%CO₂ partial pressure was only 12.02 wt%and 22.12 wt%.At the 20 vol%CO₂,when the doping amount of K₂CO₃ was 10 wt%and the sorption temperature was 600 ^oC,the CO₂ sorption capacity increased to 23.96wt%.At 50 vol%CO₂,when the doping amount of K₂CO₃ was 30 wt%and the sorption temperature was 600 ^oC,the CO₂ sorption reached 32.41 wt%.The experimental results showed that the doping of K₂CO₃ can significantly improve the CO₂ sorption performance of Li₄Si O₄ sorbent and reduce the sorption temperature.The cyclic test results showed that Li₄Si O₄ sorbent has good cycling performance after 22sorption-desorption cycles.Therefore,the synthesis of Li₄Si O₄sorbent using the sediment of Dianchi Lake as silicon source has a good application prospect.