KMnO4溶液改性半焦对烟气中气态Hg0的吸附性能研究

在小型固定床实验台上利用半焦及其KMnO₄溶液改性样品进行气态Hg⁰吸附实验。结果表明,在低温时原料半焦对气态Hg⁰具有良好的吸附性能,升温则使其吸附性能迅速降低;经高锰酸钾溶液浸渍处理后,改性半焦在高温140 ℃时吸附性能明显提高,对浸渍样品在250 ℃进行热处理可使其吸附性能进一步提高。BET结果表明,原料半焦具有较发达的微孔结构,改性处理使微孔比例下降,孔隙结构发达程度降低;XPS测试表明,改性半焦表面的汞主要以氧化态(Hg²⁺)形式存在,高价锰化合物(KMnO₄、K₂MnO₄、MnO₂)是主要的氧化活性物质。

Adsorption performance of semi-coke modified by KMnO4 solution for gas-phase Hg0 in flue gas

In an attempt to develop a novel and more effective sorbent with low-cost for the removal of gas-phase Hg⁰ from flue gas, the adsorption performance of semi-coke and KMnO₄ solution-modified semi-coke for gas-phase Hg⁰ was investigated with a bench-scale fixed-bed reactor system. The experimental results suggest that the adsorption performance of semi-coke is good at low temperature but weak at higher temperature. The semi-cokes impregnated by KMnO₄ solution have excellent adsorption performance for gas-phase Hg⁰ at 140 ℃, and can be further enhanced by heating the impregnated samples at 250 ℃. The BET analysis shows that the semi-coke has rich micro-pores but become poor after modification. The XPS results indicates that the adsorbed mercury on the surface of the modified semi-coke samples mainly exists in oxidation state (Hg²⁺) and these compounds (KMnO₄, K₂MnO₄ and MnO₂ ) play a key role in the oxidation reaction of gas-phase Hg⁰.