A Remarkable Catalyst Combination to Widen the Operating Temperature Window of the Selective Catalytic Reduction of NO by NH₃

Abstract

On the basis of the idea of combining high selective catalytic reduction (SCR) activity, high N2 selectivity, and broad operating temperature window, we developed a combined catalyst process that was found to be a convenient way to design a highly efficient SCR process for NO with NH3. The single catalysts of MnOx–CeO2/TiO2 and V2O5–WO3/TiO2 as well as combined catalysts with different configurations were fully characterized by XRD, temperature‐programmed reduction of H2, and temperature‐programmed desorption of NO/O2. In addition, they were tested for the oxidation of NO or NH3 as well as the SCR of NO with NH3. The correlations between combining configurations and SCR activity results were also revealed. Furthermore, fundamental evidences were given for the rational design of the process and its efficiency maximization (assembly order and catalytic bed volume). An adequate configuration, with MnOx–CeO2/TiO2 and V2O5–WO3/TiO2 active materials, ensures an excellent SCR performance (NO conversion >85 %, N2 yield >70 %, and decreased N2O production) over a wide operating temperature window (from 150 to 400 °C).

Tungsten-Based Catalysts for Environmental Applications

“…Developing active catalysts over a wide range of temperatures is a challenge for the NH 3 -SCR reaction. Combining two catalysts (MnO x -CeO 2 /TiO 2 (MnCeTi) and V 2 O 5 -WO 3 /TiO 2 (VWTi)), Zhang et al were able to obtain high NO conversion from 150 to 400 • C [253]. The best configuration was obtained when VWTi was set at the fore part and MnCeTi at the rear part of the catalyst bed (Figure 21, CC-B curve).…”

“…Catalysts 2021, 11, x FOR PEER REVIEW 33 of 78 reverse position; configuration CC-C: physical mixture of the two catalysts. From Zhang et al [253] with permission from John Wiley and Sons.…”

Molecular-Level Insight into Selective Catalytic Reduction of NOx with NH3 to N2 over a Highly Efficient Bifunctional Va-MnOx Catalyst at Low Temperature

“…or supported MnO x on TiO 2 , − SiO 2 , , Al 2 O 3 , ,, zeolites, − and carbon-based materials. − Improved activity and N 2 selectivity were thus achieved. The second approach is to prepare materials to develop the bifunctional catalysts, which involve the cooperation of two types of active sites with specific properties. − Several bifunctional catalysts that consist of an oxidation component (such as Mn, Mn-Ce, Mn-Cr, Mn-Cu, and Mn/Ce-Zr oxides, ,, CoO x -CuO x /TiO 2 , etc.) and an SCR-active component (such as Fe-ZSM-5, , V 2 O 5 -WO 3 /TiO 2 , Fe-beta, NiMn 2 O 4 , etc.)…”

A Highly Active and Redox-Stable SrGdNi0.2Mn0.8O4±δ Anode with in Situ Exsolution of Nanocatalysts

“…The theoretical E B values of Mn 2p 3/2 are 639.5, 641.4, and 643.0 eV for Mn 2+ , Mn 3+ , and Mn 4+ , respectively, which coincide with the deconvoluted peaks from the Mn 2p 3/2 series. , The Mn 2p 1/2 spectrum could be fitted into one or two peaks. The E B of 648.8 eV is assigned to a satellite peak of Mn 2+ . In addition, the theoretical E B values of Mn 2p 1/2 at 654.0 and 654.7 eV are assigned to Mn 2+ and Mn 3+ , respectively. , The additional peak of Mn 2+ was detected at 656.8 eV .…”