The synergy between manganese oxide and iron oxide in NO catalytic removal with MnFeO x /SiO 2 catalyst
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The synergy between manganese oxide and iron oxide in NO catalytic removal with MnFeOx/SiO2 catalyst Shaochen Gu1 · Keting Gui1 · Dongdong Ren1 · Yuliang Wei1 Received: 13 June 2020 / Accepted: 18 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The catalytic NO removal efficiencies of MnFeOx/SiO2 catalysts with different Fe/ Si were compared and studied. The reaction pathway analysis of N H3-SCR on the surface of M nFeOx/SiO2 catalyst was performed based on DFT calculations. The experimental results of catalytic activity show that the addition of an appropriate amount of iron oxide has significant improvement for the NO conversion from 240 °C to 330 °C and the N2 selectivity from 150 °C to 330 °C. The XRD test also shows that the addition of iron oxide can greatly improve the dispersion of MnO2. In addition, DFT calculations indicate that the main process of N2 formation is the NH2NO decomposition and N-NO reaction. The N-NO reaction to form N 2 is a unique reaction pathway possessed by M nFeOx/SiO2, which is the main reason for the high NO conversion and good N2 selectivity of MnFeOx/SiO2 catalyst and shows good synergy between manganese oxide and iron oxide. Keywords Density functional theory · Manganese oxide · Iron oxide · SiO2 · NH3SCR of NO
Introduction Nitrogen oxides (NOx) play key roles in air pollution and can induce the formation of photochemical smog, haze, and acid rain. This has resulted in strict environmental legislation and restrictive emission standards for nitrogen oxides. A popular commercial process to remove NOx from stationary sources such as oil- or coal-fired power plants is the selective catalytic reduction (SCR) of NO with NH3 in the presence of excess oxygen [1]. It can also be used to remove NO from diesel engine exhaust [2, 3]. The most effective industrial catalyst for the SCR of NO nowadays is V2O5/TiO2 (anatase) promoted by either W O3 or M oO3. However, because of the * Keting Gui [email protected] 1
Key laboratory of Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096, China
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Reaction Kinetics, Mechanisms and Catalysis
high operating temperatures required (>350 °C) for this catalyst, it must be located upstream of the desulfurizer and/or particulate removal device to avoid reheating the flue gas [4–8], and also cannot be applied to the wide temperature range of diesel exhaust. Recently, efforts have been made to develop catalysts capable of operating at the temperature range under 250 °C so that the catalyst can be used in the NH3-SCR devices of the power plant or the diesel engine (170–350 °C) [9]. In the developing catalysts of operating at the low-temperature range, Mn oxides, with unique redox functions, have attracted substantial attention for the control of NOx from industrial flue gas [10, 11]. Although pure MnOx possesses prominent low-temperature catalytic activity and many preparation methods [12–14] have been used to prepare different types of MnOx.
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