CaO对汞的选择性吸附及SO2毒化特性

利用Ca（NO₃）₂作为前体，SiO₂为载体，制备了一种担载型CaO吸附剂，在固定床实验装置上分别研究了该吸附剂对元素汞（Hg⁰）和氯化汞（HgCl₂）等不同形态汞的选择性吸附性能，以及SO₂对CaO吸附剂汞形态吸附过程的影响，同时结合程序升温脱附和原位红外漫反射表征技术，深入探究了CaO的选择性吸附机理及SO₂毒化机制。汞形态吸附实验结果表明，在纯N₂气氛和掺杂SO₂气氛下，CaO对Hg⁰均保持了接近100%的穿透率，而对HgCl₂在两种气氛下则分别表现出66.0%和60.3%的吸附效率，说明SO₂与HgCl₂在CaO表面存在竞争吸附关系；吸附实验前后CaO的表征结果显示，与Hg⁰相比，HgCl₂更易与CaO表面各碱性位形成单配位、双配位等多种吸附构型，SO₂与HgCl₂在易形成单配位的活性位上形成竞争吸附关系，进而在一定程度上降低了CaO对HgCl₂的吸附效率。

Mercury selective adsorption characteristics and SO2 poison performance on CaO

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.