CuO-WO3/TiO2催化氧化燃煤烟气中Hg0试验研究

Catalytic Oxidation of Elemental Mercury over CuO-WO3/TiO2 in Simulated Coal-fired Flue Gas

提高燃煤电厂现有选择性催化还原(SCR)催化剂催化氧化单质汞(Hg^0)的性能,能够有效增强燃煤电厂利用现有烟气污染物控制装置协同脱汞效率。采用分步浸渍法制备了一系列CuO-WO3/TiO2(CuWTi)催化剂,在温度150~350℃时模拟燃煤烟气条件,考察了催化氧化Hg^0性能,并与商用脱硝催化剂进行了比较。探究了烟气中O2、SO2和NO等气体对Hg^0氧化性能的影响规律。发现商用脱硝催化剂和WTi催化剂在不含HCl的模拟烟气中对Hg^0氧化率均在30%以下,而Cu2W8Ti催化剂具有较好的Hg^0氧化性能。采用X射线光电子能谱分析仪(XPS)对催化剂进行了表征,结果表明,CuO与WO3的相互作用在催化剂表面生成了丰富的化学吸附氧,促进了Hg^0的氧化。Hg^0在Cu2W8Ti催化剂表面的氧化过程遵循Mars-Maessen机制。

Improving the Hg^0 oxidation activity of the commercial selective catalytic reduction(SCR)catalyst can enhance the mercury removal activity in coal fired flue gas.In this paper,a series of CuO-WO3/TiO2(CuWTi)catalysts were synthesized by step impregnation method for oxidize elemental mercury(Hg^0)using simulated coal-fired flue gas at 150–350℃.The effects of O2,SO2 and NO on Hg^0 oxidation were also investigated and compared with commercial catalyst.The results indicated that the commercial SCR catalyst and the WTi exhibited below 30%rate on Hg^0 oxidation without HCl in simulated flue gas,while the Cu2W8Ti catalyst performed good activity of Hg^0 oxidation and NO removal.The X-ray photoelectron spectroscopy(XPS)method was used to characterize the catalysts,and the results suggested that the interaction between CuO and WO3 created abundant chemisorbed oxygen on the catalyst surface,which was beneficial for Hg^0 oxidation.The Mars-Maessen mechanism was respected in the process of the Hg^0 oxidation over Cu2W8Ti catalyst.