Study on long-term CO2 capture performance of Al2O3-doped CaO adsorbents
CaO is a kind of efficient and cheap CO2 capture adsorbents,but it is prone to sintering in the process of recycling,resulting in a significant decrease in capture capacity and making it unsuitable for long-term cyclic applications.Semi-inert Al2O3-doped CaO was used to prepare the calcium-aluminum composite adsorbents.The capture performance and cycle stability of the calcium-aluminum composite adsorbents were studied by thermogravimetric adsorption/desorption method.The regeneration performance of the calcium-aluminum composite adsorbents was further studied by air regeneration method at room temperature,and the relationships between regeneration performance and cycle times were established.The results show that the adsorption performance,cycle stability and regeneration performance of calcium-aluminum composite adsorbents are much better than those of pure CaO adsorbents because of the establishment of inert skeleton phase of Ca3Al2O6 and the formation of micro-nano structure.After 100 cycles,the CO2 adsorption capacity and carbonation conversion rate of the calcium-aluminum composite adsorbents reach 0.23 g/g and 34.0%respectively when n(Ca):n(Al)=10:1,and remain at 0.19 g/g and 32.8%respectively when n(Ca):n(Al)=10:2,but n(Ca):n(Al)should not exceed 10:2.It is proved by the deactivation mathematical model of the adsorbents that the sintering of CaO adsorbents is irreversible,and the doping of Al2O3 can inhibit the sintering of CaO adsorbents and keep the regeneration activity of calcium-aluminum composite adsorbents.The carbonation conversion rate of the calcium-aluminum composite adsorbents(n(Ca):n(Al)=10:2)after regeneration for twice under air remains basically unchanged,which is still 32.7%after 100 cycles.
CaO adsorbentsAl2O3-dopedCO2 captureair regeneration at room temperaturemultiple cycles capture
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