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Catalytic Decomposition of N2O and NO

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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) | Viewed by 34839

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Prof. Dr. Lucie Obalová

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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 NO_x (NO, NO₂) and N₂O are significant pollutants and more than 90% of emitted NO_x from stationary sources is NO. Various techniques have been developed for NO elimination, such as commercially commonly used selective catalytic reduction of NO_x (SCR) and selective noncatalytic reduction of NO_x (SNCR). In particular, less efficient SNCR technology will no longer be appropriate due to the tightening of emission limits. Compared to that, SCR NO_x 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 NO_x. 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

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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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3 pages, 185 KiB

Open AccessEditorial

Catalytic Decomposition of N₂O and NO

by Lucie Obalová

Catalysts 2021, 11(6), 667; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11060667 - 24 May 2021

Cited by 1 | Viewed by 1800

Abstract

As generally known, nitrogen oxides NO_x (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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21 pages, 6552 KiB

Open AccessFeature PaperArticle

Cobalt Based Catalysts on Alkali-Activated Zeolite Foams for N₂O Decomposition

by Zdeněk Tišler, Anna Klegová, Eliška Svobodová, Jan Šafář, Kateřina Strejcová, Jan Kohout, Stanislav Šlang, Kateřina Pacultová, Daily Rodríguez-Padrón and Roman Bulánek

Catalysts 2020, 10(12), 1398; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10121398 - 30 Nov 2020

Cited by 10 | Viewed by 2473

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 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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17 pages, 4226 KiB

Open AccessArticle

Modification of MCM-22 Zeolite and Its Derivatives with Iron for the Application in N₂O Decomposition

by Małgorzata Rutkowska, Aleksandra Jankowska, Ewelina Różycka-Dudek, Wiktoria Dubiel, Andrzej Kowalczyk, Zofia Piwowarska, Sebastián Llopis, Urbano Díaz and Lucjan Chmielarz

Catalysts 2020, 10(10), 1139; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10101139 - 02 Oct 2020

Cited by 8 | Viewed by 2658

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(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 Fe_xO_y 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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17 pages, 2191 KiB

Open AccessFeature PaperArticle

K-Modified Co–Mn–Al Mixed Oxide—Effect of Calcination Temperature on N₂O Conversion in the Presence of H₂O and NO_x

by Kateřina Karásková, Kateřina Pacultová, Květuše Jirátová, Dagmar Fridrichová, Martin Koštejn and Lucie Obalová

Catalysts 2020, 10(10), 1134; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10101134 - 01 Oct 2020

Cited by 11 | Viewed by 2215

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 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 NO_x, 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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14 pages, 2894 KiB

Open AccessArticle

Two-Stage Catalytic Abatement of N₂O Emission in Nitric Acid Plants

by Marek Inger, Bartosz Moszowski, Monika Ruszak, Jakub Rajewski and Marcin Wilk

Catalysts 2020, 10(9), 987; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10090987 - 01 Sep 2020

Cited by 5 | Viewed by 3394

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 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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22 pages, 5403 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Magnesium Effect in K/Co-Mg-Mn-Al Mixed Oxide Catalyst for Direct NO Decomposition

by Kateřina Karásková, Kateřina Pacultová, Anna Klegova, Dagmar Fridrichová, Marta Valášková, Květuše Jirátová, Paweł Stelmachowski, Andrzej Kotarba and Lucie Obalová

Catalysts 2020, 10(8), 931; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10080931 - 13 Aug 2020

Cited by 9 | Viewed by 2897

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 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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20 pages, 2025 KiB

Open AccessFeature PaperArticle

Direct Decomposition of NO over Co-Mn-Al Mixed Oxides: Effect of Ce and/or K Promoters

by Květa Jirátová, Kateřina Pacultová, Kateřina Karásková, Jana Balabánová, Martin Koštejn and Lucie Obalová

Catalysts 2020, 10(7), 808; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10070808 - 20 Jul 2020

Cited by 4 | Viewed by 2371

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 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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22 pages, 3895 KiB

Open AccessArticle

Contrasting Effects of Potassium Addition on M₃O₄ (M = Co, Fe, and Mn) Oxides during Direct NO Decomposition Catalysis

by Torin C. Peck, Charles A. Roberts and Gunugunuri K. Reddy

Catalysts 2020, 10(5), 561; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10050561 - 19 May 2020

Cited by 14 | Viewed by 2884

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 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 NO_x (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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13 pages, 2697 KiB

Open AccessArticle

Atomic-Level Dispersion of Bismuth over Co₃O₄ Nanocrystals—Outstanding Promotional Effect in Catalytic DeN₂O

by Sylwia Wójcik, Thomas Thersleff, Klaudia Gębska, Gabriela Grzybek and Andrzej Kotarba

Catalysts 2020, 10(3), 351; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10030351 - 22 Mar 2020

Cited by 6 | Viewed by 3980

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 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 (T_50%) 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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15 pages, 3417 KiB

Open AccessArticle

Bulk, Surface and Interface Promotion of Co₃O₄ for the Low-Temperature N₂O Decomposition Catalysis

by Sylwia Wójcik, Gabriela Grzybek, Paweł Stelmachowski, Zbigniew Sojka and Andrzej Kotarba

Catalysts 2020, 10(1), 41; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10010041 - 30 Dec 2019

Cited by 29 | Viewed by 4193

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 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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13 pages, 5404 KiB

Open AccessArticle

Photocatalytic Decomposition of N₂O by Using Nanostructured Graphitic Carbon Nitride/Zinc Oxide Photocatalysts Immobilized on Foam

by Kamila Kočí, Martin Reli, Ivana Troppová, Marcel Šihor, Tereza Bajcarová, Michal Ritz, Jiří Pavlovský and Petr Praus

Catalysts 2019, 9(9), 735; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9090735 - 30 Aug 2019

Cited by 15 | Viewed by 3276

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 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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