Preparation And CO₂ Adsorption Capacity Of Multi-shelled Hollow CaCO₃ Microspheres

As the major greenhouse gas,CO₂ has caused global warming issue,which has threatened human society development.To reduce the excessive emission of carbon dioxide,CO₂ capture and storage technology have draw increasing attention in the world.Face to the emission of high temperature CO₂ issue,structure characteristics and CO₂ adsorption performances of inert metal modified multi-shelled hollow CaCO₃ microsphere sorbents via templating method were studied.Novel multi-shelled hollow Mg-modified CaCO₃ microspheres were successfully prepared through a facile,green method by using carbonaceous microsphere as a template with controllable Ca/Mg molar ratio,size and shells number.The carbonaceous microsphere template was prepared via the emulsion polymerization reaction of sucrose under hydrothermal condition.The increase of shells number improved the initial CO₂ uptake due to the more active sites of CaO.Furthermore,as the microsphere size reduced,the stability and adsorption rate increased due to the short diffusion distance of CO₂.The triple-shelled hollow microspheres structure facilitated CO₂ diffusion and buffered mechanical stresses of volume change during the carbonation/calcination process.Connected with sintering-resistance of inert Mg-modification,the Mg-doped CaCO₃ triple-shelled hollow microspheres had collapse resistance,fast adsorption kinetics,improved CO₂ adsorption capacity and calcium looping stability.The sorbent TSH-C16M1-600 exhibited a favorable high temperature CO₂ adsorption performance with the capacity of 0.51 g-CO₂/g-ads after50 carbonation/calcination cycles.Keeping the shells number and microsphere diameter unchanged,double-shelled hollow Al-modified CaCO₃ microspheres with different Ca/Al molar ratio was prepared.The hollow microspheres were prepared by using different calcium source as precursor.The double-shelled hollow microspheres with denser shells structure synthesized via calcium acetate and aluminum nitrate showed excellent stability due to the shells composed with smaller CaCO₃ crystalize size and uniformed Al₂O₃ as stabilizer.The sorbent exhibited a favorable high temperature CO₂ adsorption performance with the capacity of 0.40 g-CO₂/g-ads over 60 carbonation/calcination cycles in a mild condition,and 0.43 g-CO₂/g-ads over 30 cycles in a severe condition.