SO2-tolerant NOx reduction over ceria-based catalysts: Shielding effects of hollandite Mn-Ti oxides

Khan, Mehak Nawaz; Han, Lupeng; Wang, Penglu; He, Jiebing; Ye, Bo; Yan, Tingting; Shi, Liyi; Zhang, Dengsong

doi:10.1016/j.cej.2020.125535

Cited by 56 publications

(19 citation statements)

References 55 publications

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“…However, for 3DOM CZ catalyst, the catalytic activity is greatly reduced after the introduction of SO 2 , which indicates that the addition of metal ions improves the tolerance of the catalyst to SO 2 , obviously shields the influence of SO 2 on the catalyst activity and improves the adaptability of the catalyst to the industrial simulation environment. [21][22][23] When water is introduced into the reaction gas, the activity of the catalyst begins to gradually decrease. Among them, the decline rate of the CZ catalyst is the most significant, and the NO conversion decreased by 8 % in 120 min.…”

Section: Catalyst Activitymentioning

confidence: 99%

“…Moreover, the species of adsorbed oxygen mainly exist in the defects of the catalyst (such as oxygen vacancy), and cerium can be stored by redox between Ce 4 + /Ce 3 + And release lattice oxygen. [17,21,23] Table 2 shows the O β + γ /O α + β + γ ratio of 3DOM M-CZ (M = Cr, Sn, Fe, Co, Ni, Mn, Cu) and bulk Cu CZ samples. We can find that the bulk Cu-CZ catalyst (Figure S9(B)) has a relatively low (O β + γ )/(O α + β + γ ) ratio (0.364) compared with 3DOM Cu-CZ catalyst, which also verifies that 3DOM structure helps to form more surface adsorbed oxygen species in the catalyst.…”

Section: Xps Analysismentioning

confidence: 99%

“…Mn 4 + may change into Mn 3 + , Mn 2 + with the change of electrons during the experiment, accompanied by the formation of oxygen vacancies. [12,23] The Cu2p spectrum in Figure 7(C) shows two double spin orbit peaks corresponding to Cu + (932.2 eV) and Cu 2 + (934.0 eV), respectively. [24,27] It is worth noting that in 3DOM Cu-CZ catalyst, there are a lot of low valence Cu, which is more conducive to the formation of a large number of oxygen vacancies on the catalyst surface.…”

Section: Xps Analysismentioning

confidence: 99%

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Activity Test and Mechanism Study of 3DOM Ce_0.8M_0.1Zr_0.1O₂ (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

Liu

Líu

et al. 2021

ChemCatChem

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The results show that the NO conversion rate of 3DOM Ce 0.8 Cu 0.1 Zr 0.1 O 2 catalyst at a lower temperature (150 °C) is close to 60 %. Besides, 3DOM Ce 0.8 Cu 0.1 Zr 0.1 O 2 kept a stable NO removal efficiency within a wide range of gas hourly space velocity (GHSV) and long reaction time and exhibited remarkable resistance to H 2 O and SO 2 poisoning, both individually and simultaneously. At the same time, the formation of the 3DOM structure not only improves the reduction performance and surface active sites of the catalyst, but also forms more oxygen defects and Ce 3 + in the catalyst due to the strong synergistic effect of metal ions and ceria, which improves the surface oxygen concentration of the composite oxide catalyst and further improves the catalytic activity. In addition, the doping of copper ions on the surface of the 3DOM Cu-CZ catalyst can improve the activity of the catalyst and it can get trapped by CO to form Cu + -CO, which plays an important role in the NO + CO reaction at low temperature. The existence of oxygen vacancy at high temperature is beneficial to the activation of O 2 and the dissociation of NO in the process of CO oxidation. The reaction of NO + CO over 3DOM Cu-CZ catalyst follows LÀ H and EÀ R mechanism respectively.

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Section: Catalyst Activitymentioning

confidence: 99%

Section: Xps Analysismentioning

confidence: 99%

Section: Xps Analysismentioning

confidence: 99%

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Activity Test and Mechanism Study of 3DOM Ce_0.8M_0.1Zr_0.1O₂ (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

Liu

Líu

et al. 2021

ChemCatChem

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“…Up to now, CeO 2 as the main active component and promoter of NH 3 -SCR catalysts has been widely studied [12][13][14]. In general, CeO 2 is an acid-based substance, which has a large number of Lewis acid sites and a few Brönsted acid sites.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Performance of Cerium-Based Catalysts for Selective Catalytic Reduction of Nitrogen Oxides: A Critical Review

et al. 2021

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Selective catalytic reduction of nitrogen oxides with NH3 (NH3-SCR) is still the most commonly used control technology for nitrogen oxides emission. Specifically, the application of rare earth materials has become more and more extensive. CeO2 was widely developed in NH3-SCR reaction due to its good redox performance, proper surface acidity and abundant resource reserves. Therefore, a large number of papers in the literature have described the research of cerium-based catalysts. This review critically summarized the development of the different components of cerium-based catalysts, and characterized the preparation methods, the catalytic performance and reaction mechanisms of the cerium-based catalysts for NH3-SCR. The purpose of this review is to highlight: (1) the modification effect of the various metal elements for cerium-based catalysts; (2) various synthesis methods of the cerium-based catalysts; and (3) the physicochemical properties of the various catalysts and clarify their relations to catalytic performances, particularly in the presence of SO2 and H2O. Finally, we hope that this work can give timely technical guidance and valuable insights for the applications of NH3-SCR in the field of NOx control.

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“…Nevertheless, MnO x catalysts still suffer from some challenging problems, such as narrow operation window, low N 2 selectivity, and poor resistance to H 2 O and SO 2 , which restricts their commercial application. Especially, the poor SO 2 and H 2 O tolerance of MnO x catalysts pose the greatest challenge for practical applications (Khan et al 2020;Kang et al 2020).…”

Section: Introductionmentioning

confidence: 99%

An investigation on the promoting effect of Pr modification on SO2 resistance over MnOx catalysts for selective reduction of NO with NH3

Zhai

Han

et al. 2021

Environ Sci Pollut Res

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Manganese oxides (MnO x ) exhibit excellent low-temperature activities in SCR reaction of NO with NH 3 , and they are considered as a promising catalyst for future application. However, MnO x still suffer from poor resistance to SO 2 and H 2 O. In this work, Pr was used to modify MnO x catalysts via co-precipitation process, and MnPrO x catalyst exhibited superior SO 2 resistance over pure MnO x catalyst. A series of characterization techniques, such as XRD, BET, H 2 -TPR, XPS, TG and in-situ DRIFTS, were adopted to explore the promoting effect of Pr modi cation on SO 2 resistance over MnO x catalyst in detail. The results indicated that, in the presence of SO 2 in feed gas, it seemed that PrO x rather than MnO x were apt to react with SO 2 , which was favorable to protect Mn active sites on the catalyst surface to some extent. It was known that there was strong competitive adsorption between SO 2 and NH 3 /NO species on SCR catalyst surface. In-situ DRIFTS results revealed that the adsorption of NH 3 and NO on MnO x catalyst had been severely suppressed after the introduction of SO 2 , resulting in the relevant SCR reactions following either L-H or E-R mechanisms would be inhibited obviously. But for Pr-modi ed MnO x catalyst, the introduction of SO 2 almost had no effect on the adsorption of NH 3 on catalyst surface, while it exerted a relatively noticeable impact on the adsorption of NO. As a result, SCR reactions occurred on Pr-modi ed MnO x catalyst surface could still proceed in a near-normal way through E-R rather than L-H mechanisms.Therefore, Pr modi cation on MnO x catalyst exhibited a distinctively promoting effect on SO 2 resistance performance in SCR process. HighlightsPr-modi ed MnO x catalyst exhibited superior SO 2 resistance over MnO x catalyst.Pr modi cation could inhibit the sulfation of Mn active sites on the surface of MnO x catalyst.For Pr-modi ed MnO x catalyst, the adsorption of NH 3 on Lewis acid sites was almost not affected by SO 2 , and the inhibition degree of SO 2 for NO adsorption was lower than that of MnO x catalyst.The SCR reaction on Pr-modi ed MnO x catalyst might follow E-R mechanism in the presence of SO 2 .

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SO2-tolerant NOx reduction over ceria-based catalysts: Shielding effects of hollandite Mn-Ti oxides

Cited by 56 publications

References 55 publications

Activity Test and Mechanism Study of 3DOM Ce_0.8M_0.1Zr_0.1O₂ (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

Activity Test and Mechanism Study of 3DOM Ce_0.8M_0.1Zr_0.1O₂ (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

Preparation and Performance of Cerium-Based Catalysts for Selective Catalytic Reduction of Nitrogen Oxides: A Critical Review

An investigation on the promoting effect of Pr modification on SO2 resistance over MnOx catalysts for selective reduction of NO with NH3

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SO2-tolerant NOx reduction over ceria-based catalysts: Shielding effects of hollandite Mn-Ti oxides

Cited by 56 publications

References 55 publications

Activity Test and Mechanism Study of 3DOM Ce0.8M0.1Zr0.1O2 (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

Activity Test and Mechanism Study of 3DOM Ce0.8M0.1Zr0.1O2 (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

Preparation and Performance of Cerium-Based Catalysts for Selective Catalytic Reduction of Nitrogen Oxides: A Critical Review

An investigation on the promoting effect of Pr modification on SO2 resistance over MnOx catalysts for selective reduction of NO with NH3

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Activity Test and Mechanism Study of 3DOM Ce_0.8M_0.1Zr_0.1O₂ (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

Activity Test and Mechanism Study of 3DOM Ce_0.8M_0.1Zr_0.1O₂ (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**