Tungsten modified MnOx–CeO2/ZrO2 monolith catalysts for selective catalytic reduction of NOx with ammonia

• Published in: Chemical engineering science Vol. 76; pp. 120 - 128
• Main Authors: Xu, Haidi, Zhang, Qiulin, Qiu, Chuntian, Lin, Tao, Gong, Maochu, Chen, Yaoqiang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 09.07.2012; Elsevier
• Subjects: Adsorption; ammonia; Applied sciences; Catalysis; Catalyst activation; catalysts; catalytic activity; Catalytic reactions; Chemical engineering; Chemistry; desorption; energy; Environment; Exact sciences and technology; General and physical chemistry; Monolith catalyst; NH3-selective catalytic reduction; Pollution; Reactors; Stability; temperature; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; thermal stability; tungsten; X-ray diffraction; X-ray photoelectron spectroscopy; Catalyst activation; Environment; Pollution; Stability; Monolith catalyst; NH3-selective catalytic reduction; Monolithic construction; Activation; Desorption; X ray diffraction; Thermal stability; Adsorption; NH; Titanium oxide; Selective catalytic reduction; Catalyst activity; Catalyst
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2012.04.012

A series of WO3–ZrO2 carriers were prepared by co-precipitation method with different mass fractions (0wt%, 5wt%, 10wt%, 15wt% and 20wt%) of WO3, and MnOx–CeO2/WO3–ZrO2 monolith catalysts were prepared for selective catalytic reduction of NOx 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 MnOx–CeO2/WO3–ZrO2 with the WO3 content 10wt% 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 MnOx–CeO2/ZrO2. The characterization results indicated that MnOx–CeO2/10% WO3–ZrO2 had the best textural properties, a well-dispersed state of WO3, the lowest binding energy of Ce3+ 3d5/2, the maximum value of Ce3+:Ce=20.7%, the suitable molar ratio of Mn:Ce≈1, and a co-existence state of MnO2–Mn2O3. In addition, it had the most adsorbed sites of NH3 or NO species. The NOx conversion was more than 80% in the temperature range of 150°C to 380°C at the space velocity of 10,000h−1. It possessed better potential for practical application. [Display omitted] ► WO3 modified MnOx–CeO2/ZrO2 catalysts evidently improved the SCR performance. ► An optimal WO3 loading exists providing high activity and broad reaction window. ► MnOx–CeO2/10%WO3–ZrO2 shows excellent NOx activity and thermal stability. ► The catalyst presents a better tolerance to H2O and SO2 than MnOx–CeO2/ZrO2.