Elemental mercury (Hg0) removal over spinel LiMn2O4 from coal-fired flue gas
Elemental mercury (Hg0) removal over spinel LiMn2O4 from coal-fired flue gas
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DOI：
10.1016/j.cej.2016.04.094
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发表时间：
2016-09
影响因子：
15.1
通讯作者：
Haomiao Xu;Hongbo Zhang;Songjian Zhao;Wenjun Huang;Zan Qu;N. Yan
中科院分区：
文献类型：
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作者：
Haomiao Xu;Hongbo Zhang;Songjian Zhao;Wenjun Huang;Zan Qu;N. Yan
采用溶胶-凝胶法制备了尖晶石LiMn2O4，考察了燃煤电厂气态汞(Hg0)的脱除性能。物化表征结果表明，LiMn2O4具有碱性MnO6单元和尖晶石λ-MnO2结构中的Li离子。LiMn2O4的除汞性能优于纯Mn2O3型和Li2O-Mn2O3型复合氧化物。当反应温度为150℃时，LiMn2O4对Hg0的脱除效率为93.09%(反应时间为600min)。O2提高了LiMn2O4的脱汞效率，而SO2和H2O抑制了反应，两者的共存对脱除Hg0有毒害作用。去除Hg0的主要机理是化学吸附，Hg0首先被催化氧化为Hg2+，同时高价锰(Mn4+/Mn3+)还原为低价锰(Mn3+/Mn2+)。Hg2+与吸附氧结合，以Hg2-O形式存在于LiMn2O4表面。Li离子的存在构成了λ-MnO2结构，有利于氧化过程。此外，根据Hg-TPD的结果，脱附活化能为58.82kJ/mol。
Spinel LiMn2O4was prepared using a sol–gel method to investigate gaseous elemental mercury (Hg0) removal performance from coal-fired power plants. The physical and chemical characterization results indicated that LiMn2O4had a basic MnO6unit and Li ions in the spinel λ-MnO2structure. LiMn2O4exhibited better Hg0removal performance than that of pure Mn2O3and mixed oxides of Li2O–Mn2O3. Hg0removal efficiency of LiMn2O4was 93.09% (600 min reaction) at an optimum temperature of 150 °C. Higher temperature (>200 °C) was not favorable for Hg0removal. O2enhanced the Hg0removal efficiency of LiMn2O4, while SO2and H2O inhibited the reaction, and the co-existence of them had a poison effect on Hg0removal. The primary Hg0removal mechanism was chemical-adsorption, Hg0was firstly catalytic oxidized to Hg2+along with the reduction of high valance of Mn (Mn4+/Mn3+) to low valance (Mn3+/Mn2+). Hg2+was combined with adsorbed oxygen and existed as Hg–O on LiMn2O4surface. The existence of Li ions constructs a λ-MnO2structure and benefits the oxidation process. Furthermore, based on the Hg-TPD results, the desorption activation energy was 58.82 kJ/mol.