Special Issue "Catalytic Decomposition of N2O and NO"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: closed (31 December 2020).

Special Issue Editor

Prof. Dr. Lucie Obalová
E-Mail Website
Guest Editor
Institute of Environmental Technology, VŠB – Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava, Czech Republic
Interests: Chemical and reactor engineering, Environmental catalysis and photocatalysis, Adsorption on solids, Kinetics and mechanisms of chemical reaction, Abatement of N2O and NOx from waste gases

Special Issue Information

Dear Colleagues,

Nitrogen oxides NOx (NO, NO2) and N2O are significant pollutants and more than 90% of emitted NOx from stationary sources is NO. Various techniques have been developed for NO elimination, such as commercially commonly used selective catalytic reduction of NOx (SCR) and selective noncatalytic reduction of NOx (SNCR). In particular, less efficient SNCR technology will no longer be appropriate due to the tightening of emission limits. Compared to that, SCR NOx technology is very effective, but its disadvantage, like that of SNCR, is the need to add a reducing agent (ammonia, urea), which increases costs, causes undesirable ammonia slip, and requires increased safety precautions. From this perspective, the direct catalytic decomposition of NO without a reducing agent is a challenge. Mixed oxides with alkaline metal promoters appear to be active for this reaction, but there are a number of issues that need to be addressed. These are the stability of catalysts, sufficient activity at industrially suitable temperatures, and suppression of inhibition of the reaction by oxygen and other components present in the waste gases.

Well known greenhouse gas N2O is emitted from some processes together with NOx. Even in this case, a direct catalytic decomposition is the elegant method for reducing its emissions. This technology is now at the stage of its first commercial applications, for example, in nitric acid plants. However, there is still space for increasing its efficiency through the modification of the active site, deposition of the active phase on suitable support, etc.

Another issue is an indoor and outdoor environment, where nitrogen oxides can be decomposed in the presence of suitable semiconductor materials and light with appropriate wavelength and intensity. Research findings focusing on the fundamental exploration of the syntheses, characterizations, and applications of various types of catalysts for N2O or NO catalytic or photocatalytic decomposition, as well as new knowledge about the mechanism and industrial-scale development of catalysts are of prime importance to this Special Issue.

Prof. Dr. Lucie Obalová
Guest Editor

Manuscript Submission Information

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Keywords

  • Direct NO catalytic decomposition
  • N2O catalytic decomposition
  • Photocatalytic decomposition of nitrogen oxides
  • Semiconductor photocatalysts, TiO2
  • Mixed oxide catalysts
  • Supported catalysts
  • Effect of promoters
  • Zeolites
  • Relation between methods of preparation, physicochemical and catalytic properties
  • Reaction mechanism and kinetics

Published Papers (11 papers)

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Editorial

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Editorial
Catalytic Decomposition of N2O and NO
Catalysts 2021, 11(6), 667; https://doi.org/10.3390/catal11060667 - 24 May 2021
Viewed by 488
Abstract
As generally known, nitrogen oxides NOx (NO, NO2) and nitrous oxide (N2O) are significant pollutants [...] Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)

Research

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Article
Cobalt Based Catalysts on Alkali-Activated Zeolite Foams for N2O Decomposition
Catalysts 2020, 10(12), 1398; https://doi.org/10.3390/catal10121398 - 30 Nov 2020
Cited by 2 | Viewed by 609
Abstract
In this work, we studied the effect of alkali-activated zeolite foams modifications on properties and catalytic activity of cobalt phases in the process of catalytic decomposition of N2O. The zeolite foam supports were prepared by alkali activation of natural zeolite followed [...] Read more.
In this work, we studied the effect of alkali-activated zeolite foams modifications on properties and catalytic activity of cobalt phases in the process of catalytic decomposition of N2O. The zeolite foam supports were prepared by alkali activation of natural zeolite followed by acid leaching and ion exchange. The cobalt catalysts were synthesised by a different deposition technique (direct ion exchange (DIE) and incipient wetness impregnation (IWI) method of cobalt on zeolite foams. For comparison, catalysts on selected supports were prepared and the properties of all were compared in catalytic tests in the pellet form and as crushed catalysts to determine the effect of internal diffusion. The catalysts and supports were in detail characterized by a variety of techniques. The catalyst activity strongly depended on the structure of support and synthesis procedure of a cobalt catalyst. Ion exchange method provided active phase with higher surface areas and sites with better reducibility, both of these factors contributed to higher N2O conversions of more than 80% at 450 °C. A large influence can also be attributed to the presence of alkali metals, in particular, potassium, which resulted in a modification of electronic and acid base properties of the cobalt oxide phase on the catalyst surface. The promotional effect of potassium is better reducibility of cobalt species. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Modification of MCM-22 Zeolite and Its Derivatives with Iron for the Application in N2O Decomposition
Catalysts 2020, 10(10), 1139; https://doi.org/10.3390/catal10101139 - 02 Oct 2020
Cited by 1 | Viewed by 603
Abstract
Layered 2D zeolite MCM-22 and its delaminated derivative, ITQ-2, were modified with iron, by different methods (ion-exchange and direct synthesis), and with the use of different precursors (FeSO4∙7H2O, Fe(NO3)3∙9H2O, and [Fe3(OCOCH [...] Read more.
Layered 2D zeolite MCM-22 and its delaminated derivative, ITQ-2, were modified with iron, by different methods (ion-exchange and direct synthesis), and with the use of different precursors (FeSO4∙7H2O, Fe(NO3)3∙9H2O, and [Fe3(OCOCH3)7∙OH∙2H2O]NO3 oligocations. The applied modifications were aimed at optimization of iron form in the samples (aggregation, amount, location, and reducibility), in order to achieve the highest catalytic activity in the N2O decomposition. The synthesis of the samples was verified with the use of XRD (X-Ray Diffraction), N2-sorption and ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) techniques, while the form of iron in the samples was investigated by UV–vis-DRS (UV–vis diffuse reflectance spectroscopy), H2-TPR (Hydrogen Temperature-Programmed Reduction) and HRTEM (High-Resolution Transmission Electron Microscopy). The highest activity in the N2O decomposition presented the sample Fe(O,IE)MCM-22, prepared by ion-exchange of MCM-22 with Fe3(III) oligocations. This activity was related to the oligomeric FexOy species (the main form of iron in the sample) and the higher loading of active species (in comparison to the modification with FeSO4∙7H2O). Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
K-Modified Co–Mn–Al Mixed Oxide—Effect of Calcination Temperature on N2O Conversion in the Presence of H2O and NOx
Catalysts 2020, 10(10), 1134; https://doi.org/10.3390/catal10101134 - 01 Oct 2020
Cited by 3 | Viewed by 578
Abstract
The effect of calcination temperature (500–700 °C) on physico-chemical properties and catalytic activity of 2 wt. % K/Co-Mn-Al mixed oxide for N2O decomposition was investigated. Catalysts were characterized by inductively coupled plasma spectroscopy (ICP), X-ray powder diffraction (XRD), temperature-programmed reduction by [...] Read more.
The effect of calcination temperature (500–700 °C) on physico-chemical properties and catalytic activity of 2 wt. % K/Co-Mn-Al mixed oxide for N2O decomposition was investigated. Catalysts were characterized by inductively coupled plasma spectroscopy (ICP), X-ray powder diffraction (XRD), temperature-programmed reduction by hydrogen (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), temperature-programmed desorption of NO (TPD-NO), X-ray photoelectron spectrometry (XPS) and N2 physisorption. It was found that the increase in calcination temperature caused gradual crystallization of Co-Mn-Al mixed oxide, which manifested itself in the decrease in Co2+/Co3+ and Mn3+/Mn4+ surface molar ratio, the increase in mean crystallite size leading to lowering of specific surface area and poorer reducibility. Higher surface K content normalized per unit surface led to the increase in surface basicity and adsorbed NO per unit surface. The effect of calcination temperature on catalytic activity was significant mainly in the presence of NOx, as the optimal calcination temperature of 500 °C is necessary to ensure sufficient low surface basicity, leading to the highest catalytic activity. Observed NO inhibition was caused by the formation of surface mononitrosyl species bonded to tetrahedral metal sites or nitrite species, which are stable at reaction temperatures up to 450 °C and block active sites for N2O decomposition. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Two-Stage Catalytic Abatement of N2O Emission in Nitric Acid Plants
Catalysts 2020, 10(9), 987; https://doi.org/10.3390/catal10090987 - 01 Sep 2020
Cited by 2 | Viewed by 726
Abstract
Different variants for abatement of N2O emission from nitric acid plants with the use of catalysts developed at Łukasiewicz-INS were analyzed. Activity tests on a pilot scale confirmed the high activity of the studied catalysts. A two-stage catalytic abatement of N [...] Read more.
Different variants for abatement of N2O emission from nitric acid plants with the use of catalysts developed at Łukasiewicz-INS were analyzed. Activity tests on a pilot scale confirmed the high activity of the studied catalysts. A two-stage catalytic abatement of N2O emission in nitric acid plants was proposed: by high-temperature decomposition in the nitrous gases stream (HT-deN2O) and low-temperature decomposition in the tail gas stream (LT-deN2O). The selection of the optimal variant for abatement of N2O emission depends on the individual characteristics of the nitric acid plant: ammonia oxidation parameters, construction of ammonia oxidation reactor and temperature of the tail gas upstream of the expansion turbine. It was shown that the combination of both deN2O technologies, taking into account their technological constraints (dimensions of the catalyst bed), allows for a greater abatement of N2O emission, than the use of only one technology. This solution may be economically advantageous regarding the high prices of CO2 emission allowances. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Magnesium Effect in K/Co-Mg-Mn-Al Mixed Oxide Catalyst for Direct NO Decomposition
Catalysts 2020, 10(8), 931; https://doi.org/10.3390/catal10080931 - 13 Aug 2020
Cited by 4 | Viewed by 882
Abstract
Emission of nitric oxide represents a serious environmental problem since it contributes to the formation of acid rain and photochemical smog. Potassium-modified Co-Mn-Al mixed oxide is an effective catalyst for NO decomposition. However, there are problems related to the thermal instability of potassium [...] Read more.
Emission of nitric oxide represents a serious environmental problem since it contributes to the formation of acid rain and photochemical smog. Potassium-modified Co-Mn-Al mixed oxide is an effective catalyst for NO decomposition. However, there are problems related to the thermal instability of potassium species and a high content of toxic and expensive cobalt. The reported research aimed to determine whether these shortcomings can be overcome by replacing cobalt with magnesium. Therefore, a series of Co-Mg-Mn-Al mixed oxides with different Co/Mg molar ratio and promoted by various content of potassium was investigated. The catalysts were thoroughly characterized by atomic absorption spectroscopy (AAS), temperature-programmed reduction by hydrogen (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), X-ray powder diffraction (XRD), N2 physisorption, species-resolved thermal alkali desorption (SR-TAD), and tested in direct NO decomposition with and without the addition of oxygen and water vapor. Partial substitution of magnesium for cobalt did not cause an activity decrease when the optimal molar ratio of K/Co on the normalized surface area was maintained; it means that the portion of expensive and toxic cobalt can be successfully replaced by magnesium without any decrease in catalytic activity. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Direct Decomposition of NO over Co-Mn-Al Mixed Oxides: Effect of Ce and/or K Promoters
Catalysts 2020, 10(7), 808; https://doi.org/10.3390/catal10070808 - 20 Jul 2020
Cited by 2 | Viewed by 796
Abstract
Co-Mn-Al mixed oxides promoted by potassium are known as active catalysts for the direct decomposition of nitric oxide (NO). In this study, the answer to the following question has been considered: does the presence of cerium in K-promoted Co-Mn-Al catalysts substantially affect the [...] Read more.
Co-Mn-Al mixed oxides promoted by potassium are known as active catalysts for the direct decomposition of nitric oxide (NO). In this study, the answer to the following question has been considered: does the presence of cerium in K-promoted Co-Mn-Al catalysts substantially affect the physical-chemical properties, activity, and stability in direct NO decomposition? The Co-Mn-Al, Co-Mn-Al-Ce, and Co-Mn-Al-Ce-K mixed oxide catalysts were prepared by the precipitation of corresponding metal nitrates with a solution of Na2CO3/NaOH, followed by the washing of the precipitate and calcination. Two other catalysts were prepared by impregnation of the Ce-containing catalysts with Co and Co+K nitrates. After calcination, the solids were characterized by chemical analysis, XRD, N2 physisorption, FTIR, temperature-programmed reduction, CO2 and O2 desorption (H2-TPR, CO2-TPD, O2-TPD), and X-ray photoelectron spectrometry (XPS). Cerium and especially potassium occurring in the catalysts affected the basicity, reducibility, and surface concentration of active components. Adding cerium itself did not contribute to the increase in catalytic activity, whereas the addition of cerium and potassium did. Catalytic activity in direct NO decomposition depended on combinations of both reducibility and the amount of stronger basic sites determined in the catalysts. Therefore, the increase in cobalt concentration itself in the Co-Mn-Al mixed oxide catalyst does not determine the achievement of high catalytic activity in direct NO decomposition. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Contrasting Effects of Potassium Addition on M3O4 (M = Co, Fe, and Mn) Oxides during Direct NO Decomposition Catalysis
Catalysts 2020, 10(5), 561; https://doi.org/10.3390/catal10050561 - 19 May 2020
Cited by 6 | Viewed by 752
Abstract
While the promotional effect of potassium on Co3O4 NO decomposition catalytic performance is established in the literature, it remains unknown if K is also a promoter of NO decomposition over similar simple first-row transition metal spinels like Mn3O [...] Read more.
While the promotional effect of potassium on Co3O4 NO decomposition catalytic performance is established in the literature, it remains unknown if K is also a promoter of NO decomposition over similar simple first-row transition metal spinels like Mn3O4 and Fe3O4. Thus, potassium was impregnated (0.9–3.0 wt.%) on Co3O4, Mn3O4, and Fe3O4 and evaluated for NO decomposition reactivity from 400–650 °C. The activity of Co3O4 was strongly dependent on the amount of potassium present, with a maximum of ~0.18 [(µmol NO to N2) g−1 s−1] at 0.9 wt.% K. Without potassium, Fe3O4 exhibited deactivation with time-on-stream due to a non-catalytic chemical reaction with NO forming α-Fe2O3 (hematite), which is inactive for NO decomposition. Potassium addition led to some stabilization of Fe3O4, however, γ-Fe2O3 (maghemite) and a potassium–iron mixed oxide were also formed, and catalytic activity was only observed at 650 °C and was ~50× lower than 0.9 wt.% K on Co3O4. The addition of K to Mn3O4 led to formation of potassium–manganese mixed oxide phases, which became more prevalent after reaction and were nearly inactive for NO decomposition. Characterization of fresh and spent catalysts by scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDX), in situ NO adsorption Fourier transform infrared spectroscopy, temperature programmed desorption techniques, X-ray powder diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) revealed the unique potassium promotion of Co3O4 for NO decomposition arises not only from modification of the interaction of the catalyst surface with NOx (increased potassium-nitrite formation), but also from an improved ability to desorb oxygen as product O2 while maintaining the integrity and purity of the spinel phase. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Atomic-Level Dispersion of Bismuth over Co3O4 Nanocrystals—Outstanding Promotional Effect in Catalytic DeN2O
Catalysts 2020, 10(3), 351; https://doi.org/10.3390/catal10030351 - 22 Mar 2020
Cited by 4 | Viewed by 1471
Abstract
A series of cobalt spinel catalysts doped with bismuth in a broad range of 0–15.4 wt % was prepared by the co-precipitation method. The catalysts were thoroughly characterized by several physicochemical methods (X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Raman spectroscopy (µRS), X-ray [...] Read more.
A series of cobalt spinel catalysts doped with bismuth in a broad range of 0–15.4 wt % was prepared by the co-precipitation method. The catalysts were thoroughly characterized by several physicochemical methods (X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Raman spectroscopy (µRS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption analyzed with Brunaer-Emmett-Teller theory (N2-BET), work function measurements (WF)), as well as aberration-corrected scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS). The optimal bismuth promoter content was found to be 6.6 wt %, which remarkably enhanced the performance of the cobalt spinel catalyst, shifting the N2O decomposition (deN2O) temperature window (T50%) down from approximately 400 °C (for Co3O4) to 240 °C (for the 6.6 wt % Bi-Co3O4 catalyst). The high-resolution STEM images revealed that the high activity of the 6.6 wt % Bi-Co3O4 catalyst can be associated with an even, atomic-level dispersion (3.5 at. nm−2) of bismuth over the surface of cobalt spinel nanocrystals. The improvement in catalytic activity was accompanied by an observed increase in the work function. We concluded that Bi promoted mostly the oxygen recombination step of a deN2O reaction, thus demonstrating for the first time the key role of the atomic-level dispersion of a surface promoter in deN2O reactions. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Bulk, Surface and Interface Promotion of Co3O4 for the Low-Temperature N2O Decomposition Catalysis
Catalysts 2020, 10(1), 41; https://doi.org/10.3390/catal10010041 - 30 Dec 2019
Cited by 12 | Viewed by 1272
Abstract
Nanocrystalline cobalt spinel has been recognized as a very active catalytic material for N2O decomposition. Its catalytic performance can be substantially modified by proper doping with alien cations with precise control of their loading and location (spinel surface, bulk, and spinel-dopant [...] Read more.
Nanocrystalline cobalt spinel has been recognized as a very active catalytic material for N2O decomposition. Its catalytic performance can be substantially modified by proper doping with alien cations with precise control of their loading and location (spinel surface, bulk, and spinel-dopant interface). Various doping scenarios for a rational design of the optimal catalyst for low-temperature N2O decomposition are analyzed in detail and the key reactivity descriptors are identified (content and topological localization of dopants, their redox vs. non-redox nature and catalyst work function). The obtained results are discussed in the broader context of the available literature data to establish general guidelines for the rational design of the N2O decomposition catalyst based on a cobalt spinel platform. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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Article
Photocatalytic Decomposition of N2O by Using Nanostructured Graphitic Carbon Nitride/Zinc Oxide Photocatalysts Immobilized on Foam
Catalysts 2019, 9(9), 735; https://doi.org/10.3390/catal9090735 - 30 Aug 2019
Cited by 6 | Viewed by 1132
Abstract
The aim of this work was to deposit cost-effective g-C3N4/ZnO nanocomposite photocatalysts (weight ratios of g-C3N4:ZnO from 0.05:1 to 3:1) as well as pure ZnO and g-C3N4 on Al2O3 [...] Read more.
The aim of this work was to deposit cost-effective g-C3N4/ZnO nanocomposite photocatalysts (weight ratios of g-C3N4:ZnO from 0.05:1 to 3:1) as well as pure ZnO and g-C3N4 on Al2O3 foam and to study their photocatalytic efficiency for the photocatalytic decomposition of N2O, which was studied in a home-made batch photoreactor under ultraviolet A irradiation (λ = 365 nm). Based on the photocatalysis measurements, it was found that photocatalytic decomposition of N2O in the presence of all the prepared samples was significantly higher in comparison with photolysis. The photoactivity of the investigated nanocomposite photocatalysts increased in the following order: g-C3N4/ZnO (3:1) ≈ g-C3N4/ZnO (0.45:1) ≤ g-C3N4/ZnO (2:1) ZnO < g-C3N4 < g-C3N4/ZnO (0.05:1). The g-C3N4/ZnO (0.05:1) nanocomposite showed the best photocatalytic behavior and the most effective separation of photoinduced electron–hole pairs from all nanocomposites. The key roles played in photocatalytic activity were the electron–hole separation and the position and potential of the valence and conduction band. On the other hand, the specific surface area and band gap energy were not the significant factors in N2O photocatalytic decomposition. Immobilization of the photocatalyst on the foam permits facile manipulation after photocatalytic reaction and their repeated application. Full article
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
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