Tungsten modified MnO_x-CeO₂/ZrO₂ monolith catalysts for selective catalytic reduction of NO_x with ammonia

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• 作者：Haidi Xu ; Qiulin Zhang ; Chuntian Qiu ; Tao Lin ; ^{lintaochem@scu.edu.cn} ; ^{lintao0517@sina.com} ; Maochu Gong ; Yaoqiang Chen
• 关键词：NH3-selective catalytic reduction ; Monolith catalyst ; Catalyst activation ; Environment ; Pollution ; Stability
• 刊名：Chemical Engineering Science
• 出版年：2012
• 期刊代码：18_00092509
• 类别：ce
• 出版时间：9 July, 2012
• 卷：76
• 期：Complete
• 页码：120-128
• 文件大小：1199 K

摘要

A series of WO₃-ZrO₂ carriers were prepared by co-precipitation method with different mass fractions (0 wt%, 5 wt%, 10 wt%, 15 wt%and 20 wt%) of WO₃, and MnO_x-CeO₂/WO₃-ZrO₂ monolith catalysts were prepared for selective catalytic reduction of NO_x with ammonia (NH₃-SCR) in the presence of excessive O₂. The catalysts were characterized by N₂ adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and NH₃/NO temperature-programmed desorption (NH₃/NO-TPD). The experimental results showed that, the tungsten modified monolith catalyst MnO_x-CeO₂/WO₃-ZrO₂ with the WO₃ content 10 wt%had the best catalytic activity and the widest reaction window; it possessed a better thermal stability than V₂O₅/WO₃/TiO₂ catalyst, and showed a better H₂O and SO₂ tolerance than MnO_x-CeO₂/ZrO₂. The characterization results indicated that MnO_x-CeO₂/10%WO₃-ZrO₂ had the best textural properties, a well-dispersed state of WO₃, the lowest binding energy of Ce³⁺ 3d_5/2, the maximum value of Ce³⁺:Ce=20.7%, the suitable molar ratio of Mn:Ce鈮?, and a co-existence state of MnO₂-Mn₂O₃. In addition, it had the most adsorbed sites of NH₃ or NO species. The NO_x conversion was more than 80%in the temperature range of 150 掳C to 380 掳C at the space velocity of 10,000 h^鈭?. It possessed better potential for practical application.