H2O和SO2对汞在MnO2表面吸附影响的机理研究

• 作 者: 王震 张丙凯 刘晶 杨应举 郑楚光
• 机 构: 华中科技大学煤燃烧国家重点实验室,武汉,430074;华中科技大学煤燃烧国家重点实验室,武汉430074;深圳华中科技大学研究院,深圳518000
• 出 处: 工程热物理学报
• 发表日期: 2016年6期
• 关键词: MnO2 H2O SO2 density function theory adsorption

MnO2是一种备受关注的低温SCR脱硝催化剂的活性组分材料,其不仅对NOx具有强催化还原作用,而且能够把烟气中的单质汞(Hg0)催化氧化为易脱除的氧化态汞.本文采用基于密度泛函理论的第一性原理方法研究了H2O和SO2在MnO2表面的吸附机理,并分析其对Hg0吸附的影响机制.结果表明,H2O主要吸附在MnO2(110)表面的Mn5top位,而Hg0主要吸附在Obrbridge上,因此H2O与Hg0在MnO2表面不会发生竞争吸附;SO2能稳定的吸附在MnO2(110)表面Obrbridge或者hollow位上,且SO2的吸附能小于Hg0的吸附能,故SO2会与Hg0竞争吸附,从而对Hg0在MnO2上的吸附产生不利影响.“,”MnO2 has been regarded as a potential material with excellent low temperature catalytic activity for the selective catalytic reduction of NOx with NH3,It can also significantly promote mercury oxidation.First-principle calculations based on density functional theory were performed to investigate the adsorption mechanism of H2O and SO2 on MnO2 surface,its influencing mechanism on elemental mercury adsorption on MnO2 surface were analyzed.The results show that H2O is mainly chemisorbed on Mn5 top sites of MnO2(110) surface while Hg0 is chemisorbed on Obr bridge sites,which indicates that H2O will not compete with Hg0 for adsorption sites on MnO2 surface;SO2 is strongly adsorbed on Obr bridge or hollow sites of MnO2 (110) surface with an adsorption energy higher than that of Hg0,which indicates that SO2 competes for the adsorption sites on MnO2 surface with Hg0.