Chen Yingjian, Yao Kening, Zhang Xiao, Shen Boxiong, Smith Richard Lee, Guo Haixin
School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, China; Tianjin Key Laboratory of Clean Energy and Pollution Control, Hebei University of Technology, Tianjin, China.
School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, China; Tianjin Key Laboratory of Clean Energy and Pollution Control, Hebei University of Technology, Tianjin, China.
J Hazard Mater. 2022 Aug 15;436:129109. doi: 10.1016/j.jhazmat.2022.129109. Epub 2022 May 14.
In coal-combustion energy production, presence of water vapor in flue gas causes catalyst deactivation and leads to the release of large quantities of volatile organic compounds (VOCs). In this study, design of a low-temperature, hydrophobic catalyst for flue gas purification was achieved by modifying support material with inorganic siloxane. Introduction of 5% water vapor into simulated flue gas at 300 °C reduced oxidation efficiency for o-xylene removal by 26% with unmodified MnO/γ-AlO catalyst, whereas with modified catalyst MnO-Si/γ-AlO oxidation efficiency was reduced by only 5%. MnOx-Si/γ-AlO exhibited stable catalytic efficiency for o-xylene gas oxidation containing water vapor for over 200 min. Water-resistance of the catalyst was effective for removal of multi-coal combustion pollutants (Hg and NO) and moreover, hydrophobicity of the catalyst led to a reduction in surface sulfate deposition, thereby lowering toxicity of SO from simulated flue gas. DRIFTS analysis showed that the hydrophobic catalyst surface not only reduces water adsorption, but also promotes water volatilization. Based on molecular adsorption energies, catalyst support modification with siloxane inhibits water adsorption and promotes organic adsorption and thus provides a new strategy for preparing water-resistant catalysts for flue gas purification.
在煤炭燃烧能源生产中，烟气中水蒸气的存在会导致催化剂失活，并导致大量挥发性有机化合物（VOCs）的释放。在本研究中，通过用无机硅氧烷改性载体材料，实现了一种用于烟气净化的低温疏水催化剂的设计。在300°C下，向模拟烟气中引入5%的水蒸气，未改性的MnO/γ-Al₂O₃催化剂对邻二甲苯的氧化效率降低了26%，而改性催化剂MnO-Si/γ-Al₂O₃的氧化效率仅降低了5%。MnOₓ-Si/γ-Al₂O₃对含水蒸气的邻二甲苯气体氧化表现出超过200分钟的稳定催化效率。该催化剂的耐水性对多煤燃烧污染物（Hg和NO）的去除有效，此外，催化剂的疏水性导致表面硫酸盐沉积减少，从而降低了模拟烟气中SO₂的毒性。漫反射红外傅里叶变换光谱（DRIFTS）分析表明，疏水催化剂表面不仅减少了水的吸附，还促进了水的挥发。基于分子吸附能，用硅氧烷对催化剂载体进行改性可抑制水的吸附并促进有机吸附，从而为制备用于烟气净化的耐水催化剂提供了一种新策略。
