Using Ca(NO3)2 as a precursor and SiO2 as carrier

a supported CaO adsorbent was prepared. The selective adsorption performances of elemental mercury (Hg0) and mercuric chloride (HgCl2) of the sorbent were conducted in a fixed bed

and the effects of SO2 on CaO mercury adsorption process were also investigated. At the same time

combined with the program temperature desorption (TPD) and in situ diffuse reflectance infrared spectroscopy (in-situ DRIFT) characterization technology

the selective adsorption mechanism of CaO and the mechanism of SO2 poisoning were deeply investigated. The mercury adsorption results showed that CaO maintained a breakthrough of nearly 100% for Hg0 in pure N2 atmosphere and doped SO2 atmosphere

while HgCl2 manifested 66.0% and 60.3% adsorption efficiency in two atmospheres

respectively

indicating that there was a competitive adsorption relationship between SO2 and HgCl2 on CaO surface. The characterized results of CaO before and after adsorption suggested that as compared with Hg0

HgCl2 was able to form monodentate

bidentate and other adsorption structure with the basic sites on the CaO surface. SO2 and HgCl2 formed a competitive adsorption relationship in the active sites where the bridged bidentate was easily formed

resulting in the reduction of adsorption efficiency of HgCl2 on CaO.