Performance of nano-CaCO_ 3 coated with SiO_2 on CO_2 adsorption at high temperature
Nano-CaCO_3 particles were surface-coated with SiO_2 by the sol-gel method and used as the high temperature CO_2 adsorption material.CaCO_3 samples prepared at 60—90℃ were characterized with TEM, EDS and XRD methods and the initial and final decomposition temperature were determined with TGA.The CO_2 adsorption ratio and carbonation-calcination characteristics were evaluated in a 12 mm fixed bed reactor.The analytical results showed that there was an amorphous SiO_2 film formed on the surface of nano-CaCO_3,and the atomic ratio of Si to Ca is 1∶39.The initial and final decomposition temperatures were 595—620℃ and 800—820℃ respectively.The maximum CO_2 adsorption ratio of SiO_2 coated with nano-CaCO_3 was 92.1% at 600℃with a 10% increase as compared with the uncoated nano-CaCO_3 particles.After 20 cyclic carbonation and calcination runs, CO_2 adsorption ratio of the SiO_2 coated samples was 63%.The XRD analysis illustrated that the crystal type of nano-CaCO_3 had no change after 20 cyclic runs.