Experimental Study On The Modification And Activation Of Calcium-based CO₂ Adsorbent

China's energy structure presents the status of"rich in coal,poor in oil and less in gas".Coal-fired power generation accounts for a large proportion of electricity production.A large amount of CO₂ produced by power plant end gas leads to global climate change and Greenhouse Effect aggravation.Therefore,reducing the CO₂ emissions in the process of coal power generation has become an urgent research topic.The cyclic calcination/carbonation adsorption of CO₂ with calcium-based adsorbents is an efficient,economical and easy-to-operate method for carbon capture.However,after several cycles of cyclic calcination/carbonation,the adsorption rate decreases sharply due to the sintering of the internal structure of the adsorbent,which requires not only the addition of fresh adsorbent but also the formation of a new adsorbent.This increase,but also because the waste adsorbent is not easy to deal with secondary pollution and other drawbacks.The background of this paper is coal-fired power plant,fly ash and high alumina cement were used as modified additives to modify natural limestone calcium-based sorbent—limestone,and the adsorbents with low activity after 10 cycles of adsorption were reactivated by ethanol solution to improve the adsorption capacity of the adsorbent to the CO₂.Adsorption experiments were carried out on thermogravimetric analyzer and tube furnace under different conditions,and the mechanism of modification and activation was explained by means of SEM characterization.?1?fly ash modified adsorbent and high alumina cement modified adsorbent with 1%,2%……15%mass fraction of fly ash and high alumina cement were prepared by wet mixing method,and the carbonation conditions were 15%CO₂ and 85%N₂ 600?by thermogravimetric analyzer,The calcination condition was 100%N₂ 900?for cyclic adsorption experiment,and the adsorption characteristics were studied and compared.Conclusion:the modified adsorbent with 14%fly ash and 13%high alumina cement has the best effect.The accumulative adsorption of CO₂ by ten cycles and the stability of the cycle were better.?2?The modified adsorbents with good adsorption effect were selected from the experiment of thermogravimetric analyzer.The adsorbents with 6%fly ash,10%and 14%fly ash,and 6%and 13%high alumina cement were used for further adsorption experiments in tubular furnace.The carbonation conditions were 15%CO₂,85%N₂ 700?,and the carbonation condition was 70%CO₂,30%N₂ 950?.Conclusion:the modified adsorbents with the best adsorption performance are modified adsorbents with 6%fly ash and 13%high alumina cement,respectively.The adsorption capacity of CO₂ in the 10th cycle is 135.31%and 134.04%higher than that of natural limestone,respectively.The conclusion that the best adsorbent effect is 6%fly ash,which contradicts?1?the conclusion that the best adsorbent effect is 14%fly ash,this is because 14%fly ash is easier to sinter than 6%under high temperature and high CO₂ concentration calcination conditions.?3?the adsorbents with reduced activity after 10 cycles of tube furnace were reactivated by 80%and 40%ethanol solution,respectively,and the activation effects of different activation frequencies were investigated.It is concluded that the activation effect of 80%ethanol solution is better than that of 40%ethanol solution,and the higher the activation frequency is,the better the activation frequency is.