The microstructure of the raw

calcined

and desulfurized samples of shell and limestone was detected and analyzed by SEM.Their ability of capturing SO2 was verified by using LCT-2 thermobalance and the high temperature tube reactor.The results showed that the better pore structure and smaller gas diffusion resistance of shell were in favor of the inner reaction for SO2 gas.Shell had higher calcium utilization ratio than that of limestone especially under the conditions of high reaction temperature and the increased reaction time.The bigger difference of the inner structure was found in the reaction of sulfation after calcination and direct sulfation.In direct sulfation

the reaction was restrained because of the bad pore connectivity

while the former reaction took place with good pore connectivity.