ABSTRACT:

In this study, the sulfur resistance and thermal regeneration of a series of MO_x–WO₃/TiO₂ (denoted as MW/Ti, M = Fe, Mn, Cu, V) catalysts were investigated. After in situ sulfur poisoning, the selective catalytic reduction (SCR) activity of the poisoned catalysts was inhibited at low temperatures but was promoted at high temperatures. After thermal regeneration, the FeW/Ti catalyst was more thoroughly regenerated among nonvanadium-based catalysts. To investigate the impacts of sulfur poisoning, characterizations including X-ray diffraction, thermogravimetric analysis, H₂ temperature-programmed reduction, and SO₂ temperature-programmed desorption were applied. It was discovered that different sulfur-containing species blocked the adsorption of NH₃/NO to a distinct extent over all of the catalysts, thus affecting the catalytic activity. The effect depends on which are dominant (NO or NH₃) during the reaction at different temperatures. The difference in regeneration depends on the formation of sulfate species. The ratio of M_x(SO₄)_y to NH₄HSO₄ generated on the catalysts was adopted to assess the possibility of regeneration. The ratios were 0.5, 1.4, 1.5, and 1.7 for VW/Ti, FeW/Ti, CuW/Ti, and MnW/Ti catalysts, respectively. The lower the ratio was, the easier the catalyst could be regenerated. Meanwhile, the sulfate species could be decomposed more easily on the poisoned FeW/Ti catalyst. FeW/Ti is an excellent candidate for low- and medium-temperature NH₃-SCR among nonvanadium-based catalysts.

KEYWORDS: sulfur poisoning, thermal regeneration, NH₃-SCR, MO_x-WO₃/TiO₂

摘要:

文章研究了MO_x-WO₃/TiO₂(MW/Ti, M =Fe,Mn,Cu,V)系列催化剂的耐硫性和热再生性能。原位的硫中毒处理后，催化剂的选择性催化还原（NH₃-SCR）活性在低温下受到抑制，而在高温下则被促进。热再生处理后，非钒基催化剂中FeW/Ti催化剂的再生更为彻底。采用X射线衍射、热重分析、程序升温还原和程序升温解吸等表征手段研究了硫中毒对催化剂的影响。研究发现，含硫物质在不同催化剂上对NH₃或者NO的吸附阻碍程度不同，从而影响了催化活性变化差异。这一影响取决于NO或NH₃在不同温度下的反应中谁占主导地位。再生的差异取决于硫酸盐种的形成。采用催化剂生成的M_x(SO₄)_y与NH₄HSO₄的比值来评估再生的可能性，VW/Ti、FeW/Ti、CuW/Ti和MnW/Ti催化剂的上述比值分别为0.5、1.4、1.5和1.7。比例越低，催化剂越容易再生。同时，硫酸盐在FeW/Ti催化剂上更易分解,说明在非钒基催化剂的研究中，FeW/Ti催化剂是低温和中温NH₃-SCR催化剂潜在的替代材料。

关键词: 硫中毒，热再生，NH₃-SCR，MO_x-WO₃/TiO₂

原载于Environmental Science & Technology（2019 Impact Factor = 7.864）

原文链接： 

https://pubs.acs.org/doi/10.1021/acs.est.0c02840