烟气组分对汞吸附影响的程序升温脱附

目前燃煤烟气活性炭脱汞技术已经很成熟，但机理方面的相关研究甚少或不全面，为了探讨汞与活性炭在燃煤烟气中的反应路径，本文在固定床上对商业活性炭（FAC）和1% NH₄Br改性活性炭（NBAC）进行了汞吸附实验，分别考察了O₂、SO₂、CO₂、NO及其混合烟气组分对吸附剂汞吸附的影响，然后利用程序升温脱附（temperature programmed desorption，TPD）技术分析了烟气组分对汞吸附的影响机理。固定床测试结果表明溴化铵改性可显著增加活性炭汞吸附性能，O₂、CO₂及NO可促进NBAC对汞的吸附，其中NO最好，而SO₂抑制NBAC对汞的吸附。TPD结果表明，溴素改性促进NBAC表面负载的溴与Hg⁰结合生成HgBr₂，O₂存在促进了Hg⁰的氧化生成HgO，NO存在显著增加了Hg₂（NO₃）₂的生成。SO₂与Hg⁰对活性炭表面的官能团存在竞争吸附的关系，生成C-S，与Hg⁰反应生成HgS。CO₂对NBAC吸附Hg⁰的反应机理影响不大。

Temperature programmed desorption(TPD)studies on the effect of flue gas component on mercury adsorption

Removing mercury technology of activated carbon in flue gases is very mature. However, the mechanism of the mercury reaction is seldom.Experiments on mercury capture by a commercial activated carbon and a 1% NH₄Br-modified activated carbon were carried out in a fixed-bed reactor under simulated flue gas to study the reaction path among the mercury,flue gas and activated carbon. The effect of single component such as O₂,CO₂,SO₂ and NO was investigated. Then the temperature programmed desorption technique was used to identify the mercury species on the adsorption products. The results showed that the bromine impregnation on the activated carbon has a great promotion on the mercury capture. O₂ and CO₂ play a positive role in the mercury capture process,while the SO₂ plays a negative function. According to the TPD analysis results,NO promotes mercury capture significantly because of the formation Hg₂(NO₃)₂ on the activated carbon surface. The elemental mercury was oxidized to generate HgO when O₂ was injected.SO₂ competed with Hg⁰ on the surface functional groups of activated carbon and HgS was formed because of C-S was formed to react with Hg⁰.CO₂ has little effect on the adsorption mechanism of NBAC.