改性SCR催化剂对单质汞氧化性能的研究

在模拟SCR反应器烟气组分下,考察了过渡金属改性掺杂对SCR催化剂单质汞(Hg0)氧化性能的影响。采用N2吸附-脱附和X射线衍射(XRD)对催化剂理化性能进行表征。结果表明,金属改性掺杂减小了催化剂的比表面积和总孔容,但对催化剂的孔径分布没有太大的影响。XRD谱图中出现了微弱的过渡金属氧化物衍射峰。8%Ce/SCR和8%Cu/SCR催化剂表现出了相对稳定和高效的Hg~0氧化效率,而8%Co/SCR催化剂Hg~0氧化效率受温度影响较大。金属改性掺杂的催化剂在低NH_3和NO烟气组分中表现出较好的Hg~0氧化效率,当烟气组分中存在HCl时,促进更加明显;而当催化剂在高NH3和NO烟气组分条件下,即使有HCl的存在对Hg~0氧化效率影响也不大。

Oxidation of elemental mercury over modified SCR catalysts

The oxidation activity of elemental mercury (Hg⁰) by transition metal modified SCR catalysts was investigated by using the simulated SCR reactor. The physical and chemical properties of the catalysts were characterized by N₂ adsorption-desorption and X-ray diffraction (XRD). The results show that the specific surface area and total pore volume of the catalysts are decreased after the modification by metal oxide. However, the pore structure and distribution after modification have little variation. The weak diffraction peaks of transition metal oxide can be seen from the XRD pattern. Both 8% Ce/SCR and 8% Cu/SCR catalysts show a relatively stable and high Hg⁰ oxidation efficiency, while the oxidation activity of the 8% Co/SCR catalyst is greatly influenced by temperature. The modified SCR catalysts have an excellent catalytic performance for the Hg⁰ oxidation under a lower concentration of NH₃ and NO. And the Hg⁰ oxidation efficiency is promoted significantly in the presence of HCl. On the contrary, there is little improvement in the Hg⁰ oxidation by HCl at the condition of higher concentration of NH₃ and NO.