Littérature scientifique sur le sujet « Nitrogen oxide decomposition »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Sommaire
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Nitrogen oxide decomposition ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Nitrogen oxide decomposition"
1
Obalová, Lucie. « Catalytic Decomposition of N2O and NO ». Catalysts 11, no 6 (24 mai 2021) : 667. http://dx.doi.org/10.3390/catal11060667.
Texte intégral
2
McLarnon, C. R., et V. K. Mathur. « Nitrogen Oxide Decomposition by Barrier Discharge ». Industrial & ; Engineering Chemistry Research 39, no 8 (août 2000) : 2779–87. http://dx.doi.org/10.1021/ie990754q.
Texte intégral
3
POUR, V., et Z. SOBALIK. « ChemInform Abstract : Catalytic Decomposition of Nitrogen Oxide ». ChemInform 25, no 2 (19 août 2010) : no. http://dx.doi.org/10.1002/chin.199402303.
Texte intégral
4
Kulish, O. N., K. I. Zaporozhskiy, S. A. Kuzhevatov, M. N. Orlova, V. M. Senyavin et I. Sh Gleyzer. « Reducing the Formation of Secondary Pollutants in the Process of NonCatalytic Purification of Flue Gases from Nitrogen Oxides ». Ecology and Industry of Russia 24, no 7 (15 juillet 2020) : 8–11. http://dx.doi.org/10.18412/1816-0395-2020-7-8-11.
Texte intégralRésumé :
The possibilities of the technology of non-catalytic reduction of nitrogen oxides (SNCR) to reduce the possible formation of secondary pollutants: ammonia, carbon monoxide and nitric oxide (I) are considered. The conditions for the process of reduction of nitrogen oxides by the thermal decomposition products of urea with a minimum formation of the above pollutants are determined.
5
SWAMY, C. S., et J. CHRISTOPHER. « ChemInform Abstract : Decomposition of Nitrogen Oxide (N2O) on Perovskite-Related Oxides ». ChemInform 24, no 43 (20 août 2010) : no. http://dx.doi.org/10.1002/chin.199343274.
Texte intégral
6
Shukla, M. K., Balendra V. S. Chauhan, Sneha Verma et Atul Dhar. « Catalytic Direct Decomposition of NOx Using Non-Noble Metal Catalysts ». Solids 3, no 4 (2 décembre 2022) : 665–83. http://dx.doi.org/10.3390/solids3040041.
Texte intégralRésumé :
Nitrogen oxides (NOx) gases, such as nitrous oxide (N2O), nitrogen oxide (NO), and nitrogen dioxide (NO2), are considered the most hazardous exhausts exhaled by industries and stationary and non-stationary application engines. Investigation of catalytic decomposition of NO has been carried out on copper ion exchanged with different bases, such as COK12, Nb2O5, Y-zeolite, and ZSM5. The catalytic decomposition of NO is widely accepted as an excellent method for the abatement of NO. However, the catalyst that achieves the highest reactivity in terms of NO decomposition is still a matter of research. The present paper aims to extend the research on the reactivity of non-noble metal-based catalysts using the direct decomposition method to remove NO from diesel engine exhaust. The reactivity of catalysts was observed in a quartz fixed bed reactor of 10 mm diameter placed in a furnace maintained at a temperature of 200 °C to 600 °C. The flow of NO was controlled by a mass flow controller, and the gas chromatography technique was used to observe the reactivity of the catalysts. Analysis showed that adding Cu to COK12, Nb2O5, Y-zeolite, and ZSM5 supports resulted in a rise in NO decomposition compared to stand-alone supports. Further experimental trials on the performance of Cu-ZSM5 at varying flow rates of NO showed that the NO decomposition activity of the catalyst was higher at lower flow rates of NO.
7
Ongar, Bulbul, Hristo Beloev, Iliya Iliev, Assem Ibrasheva et Anara Yegzekova. « Numerical simulation of nitrogen oxide formation in dust furnaces ». EUREKA : Physics and Engineering, no 1 (10 janvier 2022) : 23–33. http://dx.doi.org/10.21303/2461-4262.2022.002102.
Texte intégralRésumé :
Even though natural sources of air pollution account for over 50 % of sulphur compounds, 93 % of nitrogen oxide which are the most dangerous artificial anthropogenic sources of air pollution and primarily associated with the combustion of fossil fuel. Coal-fired thermal power plants and industrial fuel-burning plants that emit large quantities of nitrogen oxides (NО and NО2), solids (ash, dust, soot), as well as carbon oxides, aldehydes, organic acids into the atmosphere pollute the environment in majority. In the present work, a mathematical model and a scheme for calculating the formation of nitrogen oxide has been developed. Also, the dependence of the rate of release of fuel nitrogen from coal particles at the initial stage of gasification and content of volatiles has been obtained. The main regularities of the formation of NOx at the initial section of the flame in the ignition zone of the swirl burner flame during the combustion of Ekibastuz coal have been revealed. Modern environmental requirements for the modernization of existing and the creation of new heat and power facilities determine the exceptional relevance of the development of effective methods and constructions to reduce emissions of nitrogen oxides, sulfur oxides and ash to 200, 300, and 100 mg/nm3 at a=1.4. The dust consumption in all experiments was kept constant and amounted to 0.042 g/s, as well as with the results of calculating the thermal decomposition of the Ekibastuz coal dust, the recombination of atomic nitrogen into nitrogen molecules, and the kinetics of the formation of fuel nitric oxide.
It was found that despite the presence of oxygen in Ekibastuz coal for gases Odaf=11.8 % in an inert atmosphere, nitrogen oxides are not formed
8
Cvetanović, Sveta. « Overview of nitrogen oxide reactions during fossil fuel combustion in the atmosphere ». Safety Engineering 10, no 2 (2020) : 103–8. http://dx.doi.org/10.5937/se2002103c.
Texte intégralRésumé :
This paper discusses the reactions of formation and decomposition of nitrogen oxides during fossil fuel combustion and in the atmosphere. Information about the chemical processes of pollutant formation and decomposition is the basis for the development of theoretical models of pollutant emissions. The information also provides a clearer picture about the primary factors influencing emissions. Nitrogen oxides are pollutants that damage human health, living and nonliving nature, and material property.
9
Voitko, K. V., O. M. Bakalinska, Yu V. Goshovska, Yu I. Sementsov et M. T. Kartel. « Catalase-like properties of multilayer graphene oxides and their modified forms ». Surface 12(27) (30 décembre 2020) : 251–62. http://dx.doi.org/10.15407/surface.2020.12.251.
Texte intégralRésumé :
The catalytic system, that mimets catalase enzyme such as “multilayer graphene oxide /peroxide molecule” in aqueous media was investigated. The main factors that influence on catalyst’s effectiveness were determining. The catalytic activity of as-synthesized multilayered graphene oxides, and their modified forms (oxidized and nitrogen doped) were investigated in the decomposition of hydrogen peroxides at room temperature and physiological pHs by measuring the volume of released gases. A phosphate buffer with a pH of 5 to 8 was chosen as the reaction medium. The original and modified samples were characterized using XPS, TPD-MS, Boehm titration analyses. The effect of surface chemistry on the catalytic reaction proceeding has been studied. It was found that catalysis on the graphene plane is determined by the presence of heteroatoms in their structure. The catalytic process takes place in the kinetic zone over the entire accessible surface of the samples. The active sites of the catalysts contain a large amount of both nitrogen and oxygen-containing functional groups. In addition, the surface of graphene oxide is hydrophilic, which enhances the catalytic reaction in an aqueous medium. It has been established that the rate of hydrogen peroxide decomposition by reduced graphene oxide samples is lower than for samples modified with oxygen and nitrogen. The catalase-like activity of graphene increases in alkaline pH up to 7.8. Studies have shown that samples of multilayer graphenes with a high content of functional groups can be an alternative to the catalase enzyme as a catalyst for the decomposition of hydrogen peroxide in physiological solutions.
10
Frenzel, Nancy, Torsten Otremba, Reinhard Schomäcker, Thorsten Ressler et Martin Lerch. « Präparation und Charakterisierung von SiO2-geträgerten Zirconiumoxidnitriden mit hoher Oberfläche und Untersuchung ihrer katalytischen Aktivität bei der Ammoniakzersetzung / Synthesis, Characterization, and Catalytic Activity of Zirconium Oxide Nitrides Supported on High-surface SiO2 ». Zeitschrift für Naturforschung B 66, no 2 (1 février 2011) : 147–54. http://dx.doi.org/10.1515/znb-2011-0207.
Texte intégralRésumé :
Zirconium oxide nitrides are active ammonia decomposition catalysts for the production of hydrogen. We present a route to zirconium oxide nitrides with high surface area. The precursor used consisted of a high-surface-area silica material coated with zirconium alkoxide. Subsequent hydrolysis and calcination resulted in ZrO2 supported on SiO2. The high surface area of the material could be maintained in the following ammonolysis procedure leading to the corresponding zirconium oxide nitride. In contrast to the as-prepared ZrO2, the zirconium oxide nitrides exhibited a significant catalytic activity in ammonia decomposition, but compared to an iron oxide-based reference material, the new oxide nitrides showed a rather low activity. Nevertheless, zirconium oxide nitrides constitute suitable model systems for elucidating the effect of nitrogen in the anion substructure on the activity and selectivity of oxide-based ammonia decomposition catalysts.
Thèses sur le sujet "Nitrogen oxide decomposition"
1
Hannon, Andrew Michael. « Exploring the Reactivity and Decomposition of Ruthenium Nitrosyl Complexes for the Production of Nitrogen Oxides ». Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/243113.
Texte intégralRésumé :
Nitric oxide (NO) has been shown to both suppress and promote tumor growth, depending in part on concentration. Exogenous delivery of NO may lead to tumor suppression. Recent studies have proposed ruthenium nitrosyl complexes as catalytic donors of NO in reductive environments. Catalytic donation can provide a long-term, elevated NO flux compared to single use donors. Site-specific delivery is desirable to reduce systemic side effects, such as lowering of blood pressure. Three new ruthenium nitrosyl complexes were synthesized to impart site-specificity through amide coupling to polymers, silica nanoparticles, iron oxide nanoparticles and antibodies. The catalytic activity of new and existing compounds was then assessed. However, upon one-electron reduction of ruthenium nitrosyl complexes, insignificant amounts of NO were detected, suggesting an alternative mechanism than that proposed in prior reports. The mechanism of [Ru(EDTA)NO]²⁻ decay was more thoroughly analyzed. Spectrophotometric decay of [Ru(EDTA)NO]²⁻ indicates that one or multiple nitrogen oxide species are released. Previous studies have suggested a disproportionation mechanism leading to the generation of more highly reduced species such as N₂ and NH₄⁺. Experiments were designed to analyze possible decomposition products such as [Ru(EDTA)NO]⁻ and [Ru(EDTA)H₂O]²⁻. A disproportionation mechanism was determined likely. Decomposition of [Ru(EDTA)NO]²⁻ was also observable following reductive nitrosylation of [Ru(EDTA)H₂O]⁻ in the presence of HNO. The decomposition product, [Ru(EDTA)H₂O]²⁻, was observed through the binding of pyrazine (pz) or dipyridine (bipy) and formation of [Ru(EDTA)pz]²⁻ or [Ru(EDTA)bipy]³⁻. Formation of [Ru(EDTA)bipy]³⁻ or [Ru(EDTA)pz]²⁻ via reductive nitrosylation of [Ru(EDTA)H₂O]⁻ also provides an indirect method of HNO detection that is selective from NO.
2
Munro, Andrew P. « S-nitrosothiols : novel decomposition pathways including reactions with sulfur and nitrogen nucleophiles ». Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4605/.
Texte intégralRésumé :
Spectrophotometric (including stopped-flow) techniques were used to examine the kinetics of NO-group transfer reactions (transnitrosation) between S-nitrosothiols (RSNO) and a wide range of sulfur/nitrogen nucleophiles in aqueous solution. A metal-ion chelator was added in all experiments to prevent RSNO decay and NO liberation catalysed by copper ions. In most cases reaction was envisaged as rate- determining attack of the nucleophile at the nitrogen atom of the -SNO moiety, and hence S-nitrosothiols essentially acted as electrophilic nitrosating agents. Sulfite, thiosulfate, thiourea, thiocyanate and thiomethoxide, were sufficiently nucleophilic to induce nitrosothiol decomposition at physiological pH. Reaction with sulfide (pH > 7.4) afforded the orange-yellow anion, SSNO, and embodies a potential quantitative test for RSNOs. S-Nitrosopenicillamine was reactive enough to allow a thorough investigation into its reaction at basic pH with primary, secondary (creating carcinogenic N-nitrosamines), and tertiary amines, as well as ambident (e.g. thiomorpholine) and alpha nucleophiles (e.g. azide ion). Parallels could be made with analogous studies using other nitroso compounds such as MNTS. The generality of the reaction of a S-nitrosothiol with a large excess of the corresponding or a different thiol was also assessed. Ammonia and not nitric oxide was confirmed as the primary nitrogenous product of this highly complicated process. Mechanistic details of the copper(I) catalysed decomposition of some novel S- nitroso derivatives (e.g. a synthesised S-nitroso-1 -thiosugar) are reported. The two- stage degradation pathway involved an initial Cu(^+) promoted component that halted at incomplete conversion, and was accompanied by a large thermal reaction. An explanation of this unique pattern has been offered in terms of the generation of a disulfide-Cu(^2+) complex, in which copper is/is not accessible to reduction.
3
Khader, Mahmoud M. « Photoassisted solid-catalysed reduction of nitrogen by water and decomposition of water over partially reduced ferric oxide ». Thesis, Boston University, 1988. https://hdl.handle.net/2144/38055.
Texte intégralRésumé :
Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Partially reduced ferric oxide was found to be an active photocatalyst for the production of H2 from water and NH3 from N2 and H2O. The catalyst was prepared by reducing α-Fe2O3 in a mixture of H2 and H2O vapor, and then oxidizing it in air. It was used in the form of powder, sintered pellets and sputtered thin films. X-ray diffraction and oxidimetry showed that the active samples contain about 5 mole% Fe(II). Surface characterization of thin films of iron oxide deposited by d.c. sputtering on Pt substrates was carried out in an ultrahigh vacuum (UHV) chamber using Auger electron spectroscopy (AES), thermal desorption spectroscopy (TDS) and low energy electron diffraction (LEED). Water desorption from thin films of stoichiometric ferric oxide exhibited zero order kinetics and yielded a single peak at 170 K. By contrast, TDS of H2O from partially reduced films showed two H2O desorption peaks at 170 and 225 K. Ordered overlayers of iron oxide on Pt(111) were detected by LEED. In a photoelectrochemical (PEC) cell, partially reduced iron oxide served as a photoanode. The material proved to be an n-type semiconductor with low dark currents and high anodic photocurrents when irradiated with light of energy greater than 2.2 eV. Photolysis of water to H2 and O2 over the partially reduced ferric oxide was shown to be a catalytic process with H2 yields higher than the stoichiometric reducing capacity of the catalyst observed. In a photoelectrochemical cell, the threshold photon energy for H2 formation was 2.2-2.3 eV. The rate of evolution of H2 and photocurrent increased with biasing voltage with no indication of any saturation, and also increased linearly with light intensity. At voltages below +0.7 V versus a saturated calomel electrode (SCE) the rate of hydrogen production and photocurrent varied linearly with each other. NH3 was formed when N2 at atmospheric pressure, saturated with water vapor, was bubbled through a suspension of α-Fe2O3 powder in H2O illuminated by 20 mW/cm^2 of light of wavelengths from 4200 Aº to 27500 Aº. The estimated maximum turnover frequency (TOF) was 1.3 x 10^-5 molecules/site.sec. In the presence of formaldehyde or glucose the TOF of ammonia formation was 1.7 x 10^-4 and 1.3 x 10^-4 molecule/site.sec, respectively. These rates declined when the reaction proceeded for longer time. Ammonia synthesis over partially reduced iron oxide was also shown to be catalytic, with a threshold for production at a photon energy of 2.2 eV. The rate of ammonia formation over partially reduced ferric oxide increased to a maximum at a light intensity of 20 mW/cm^2, after which it decreased at higher light intensities. The rate of ammonia formation was also found to increase linearly with volume of water per unit weight of catalyst. Pure ammonia photodecomposed to N2 and H2 over the partially reduced ferric oxide, but in the presence of O2 it photodecomposed to N2 and H2O.
2031-01-01
4
Graul, Théodore. « Production of biocarbon catalysts for NOx decomposition, WGS and RWGS ». Electronic Thesis or Diss., Ecole nationale des Mines d'Albi-Carmaux, 2023. http://www.theses.fr/2023EMAC0017.
Texte intégralRésumé :
Ce travail propose une approche innovante pour la production, caractérisation et utilisation de catalyseurs biosourcés pour des applications dans les domaines de l'énergie et de l'environnement, afin de réduire le coût et l'impact des catalyseurs commerciaux actuellement utilisés. Le travail développé ici promeut une approche d'économie circulaire dans la mesure où des plantes issues de la phytoremédiation ont été employées pour la production de catalyseurs biosourcés, respectueux de l'environnement. Ces catalyseurs ont été utilisés pour produire des vecteurs énergétiques tels que l'hydrogène à partir des réactions de gaz à l'eau direct (water-gas shift, WGS) et indirect (reverse water-gas shift, RWGS), et pour la décomposition des polluants de NOx (deNOx). Les catalyseurs biosourcés ont été produits à partir de saule et fougère avec un contenu contrôlé en métaux introduit par imprégnation avant ou après pyrolyse à 800°C afin d'imiter l'hyperaccumulation (>3 g métal /kg biocarbone) dans un support carboné poreux. Les catalyseurs ainsi produits ont été testés pour les réactions de deNOx, ainsi que dans WGS et RWGS, et les dispositifs expérimentaux associés ont été développés et optimisés pendant la thèse. Ils ont été caractérisés en termes de composition, structure et stabilité thermique, ceci avant et après utilisation. Pour les trois réactions, les catalyseurs ont montré une sélectivité et une conversion élevées et maintenues dans les conditions de réaction, facilitées par le contenu en métaux catalytiques dont l'activité a été renforcée par les métaux inhérents. La présence de fonctions oxygénées de surface et d'une surface spécifique élevée (<419 m²/g) ont amélioré l'adsorption et la dissociation des gaz réactifs grâce à des sites supplémentaires formés par réduction et à une meilleure activité électronique. Avec ces caractéristiques, les catalyseurs biosourcés ont montré des performances meilleures que celles de catalyseurs références de la littérature en raison d'une meilleure stabilité ou activité catalytiques (conversion maintenue pour plus de 120h, énergie d'activation entre 0.5 et 186 kJ/mol, constante cinétique entre 1.9 x 10^-9 et 4.3 x 10^12. Le catalyseur de saule imprégné au Ni avant pyrolyse et le catalyseur bimétallique (Ni/Fe) de fougère ont montré les meilleures performances pour les réactions de deNOx, et RWGS et WGS, respectivementThis work proposes an innovative approach to the production, characterization and use of biocarbon catalysts for energy and environment-related applications, in order to reduce the cost and impact of the commercial catalysts currently in use. The work developed here promotes a circular economy approach in the way that plants from phytoremediation have been used for the production of eco-friendly biocarbon catalysts. They were used for the production of energy vectors such as hydrogen by direct and reverse water-gas shift reaction (WGS and RWGS respectively), as well as for the decomposition of NOx pollutants (deNOx). Biocarbon catalysts were produced from willow and fern with a controlled metal content introduced by wet impregnation before or after pyrolysis at 800°C to imitate hyperaccumulation (>3 g metal/kg biocarbon) in a porous carbon support. The resulting catalysts were tested in deNOx, as well as WGS and RWGS reactions, and the associated experimental equipments were developed and optimized during this thesis work. They were characterized in terms of composition, structure and thermal stability, before and after use. For the three reactions, the catalysts showed high selectivity and conversion, facilitated by the catalytic metals whose activity was enhanced by the inherent metals. The presence of surface oxygen functions and a high specific surface area (<419 m²/g) improved adsorption and dissociation of reactive gases thanks to additional reactive sites formed by reduction and enhanced electronic activity. With these characteristics, biocarbon catalysts showed better performances than literature-based reference catalysts as they were either more stable or active (conversion maintained for more than 120h, activation energy from 0.5 to 186 kJ/mol, kinetic constant between 1.9 x 10^-9 and 4.3 x 10^12). Willow biocarbon impregnated with Ni before pyrolysis and bimetallic (Ni/Fe) fern biocarbon showed the best performances for the deNOx, and RWGS and WGS reactions, respectively
5
Vijay, Rohit. « Discovery and mechanistic investigation of nitrogen oxides traps and ammonia decomposition catalysts using high-throughput experimentation ». Access to citation, abstract and download form provided by ProQuest Information and Learning Company ; downloadable PDF file, 346 p, 2008. http://proquest.umi.com/pqdweb?did=1459913411&sid=9&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Texte intégral
6
Johar, Jasmeet Singh. « An experimental investigation of the urea-water decomposition and selective catalytic reduction (SCR) of nitric oxides with urea using V2O5-WO3-TiO2 catalyst ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/2595.
Texte intégralRésumé :
Two flow reactor studies, using an electrically heated laminar flow reactor over
Vanadia based (V2O5-WO3/TiO2) honeycomb catalyst, were performed at 1 atm pressure
and various temperatures. The experiments were conducted using simulated exhaust gas
compositions for different exhaust gases. A quartz tube was used in order to establish
inert conditions inside the reactor. The experiments utilized a Fourier transform infrared
(FTIR) spectrometer in order to perform both qualitative and quantitative analysis of the
reaction products.
Urea-water solution decomposition was investigated over V2O5-WO3/TiO2 catalyst
over the entire SCR temperature range using the temperature controlled flow reactor.
The solution was preheated and then injected into pure nitrogen (N2) stream. The decomposition
experiments were conducted with a number of oxygen (O2) compositions (0,
1, 10, and 15%) over the temperature range of 227oC to 477oC. The study showed ammonia
(NH3), carbon-dioxide (CO2) and nitric oxide (NO) as the major products of decomposition
along with other products such as nitrous oxide (N2O) and nitrogen dioxide
(NO2).
The selective catalytic reduction (SCR) of nitric oxide (NO) with urea-water solution
over V2O5-WO3/TiO2 catalyst using a laboratory laminar-flow reactor was investigated.
Urea-water solution was injected at a temperature higher than the vaporization
temperature of water and the flow reactor temperature was varied from 127oC to 477oC.
A FTIR spectrometer was used to determine the concentrations of the product species. The major products of SCR reduction were NH3, NO and CO2 along with the presence
of other minor products NO2 and N2O. NO removal of up to 87% was observed.
The aim of the urea-water decomposition experiments was to study the decomposition
process as close to the SCR configuration as possible. The aim of the SCR experiments
was to delineate the effect of various parameters including reaction temperature
and O2 concentration on the reduction process. The SCR investigation showed that
changing parameter values significantly affected the NO removal, the residual NH3 concentration,
the temperature of the maximum NO reduction, and the temperature of complete
NH3 conversion. In the presence of O2, the reaction temperature for maximum NO
reduction was 377?C for ratio of 1.0.
7
Matam, Santhosh Kumar. « On the nature of different Fe sites on Fe-containing micro and mesoporous materials and their catalytic role in the abatement of nitrogen oxides from exhaust gases ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2005. http://dx.doi.org/10.18452/15354.
Texte intégralRésumé :
Gegenstand der Untersuchungen war die Reduktion von Stickoxiden (NOx und N2O) an verschiedenartig präparierten Eisenkatalysatoren (Fe-MF, Fe-beta, Fe-SBA-15). Die Katalysatoren wurden nach Synthese, Kalzinierung und Katalyse mittels EPR und UV/VIS-DRS charakterisiert, und darüber hinaus auch in-situ während des Kalzinierens. Isolierte Eisenspezies aggregieren im Verlauf der Kalzinierung bei 873 K. Sowohl höhere Heizraten beim Kalziniervorgang, als auch ein höheres Si/Al-Verhältnis des Trägermaterials verstärken die Neigung zur Aggregatbildung leicht. Die Verwendung des Katalysators für die SCR von NO führt zu weiterem Wachstum und zur Restrukturierung der FexOy-Cluster. Die Eisenkatalysatoren wurden weiterhin mittels in-situ Methoden (EPR, UV/VIS-DRS, FTIR) untersucht während der SCR von NO durch NH3 und Isobutan, der SCR von N2O mit CO, und im Strom der entsprechenden reinen Eduktgase. Die Ergebnisse korrelieren mit dem katalytischen Verhalten der Materialien. Verschiedene Fe3+-Spezies, welche sich durch ein unterschiedliches Redoxverhalten auszeichnen, wurden identifiziert. UV/VIS-Messungen erlauben die Schlußfolgerung, daß isolierte, oktaedrisch koordinierte Fe3+?Spezies leichter zu reduzieren sind als tetradrisch koordinierte. Im Gegensatz zu isoliertem Fe3+ lassen sich FexOx-Cluster leichter oxidieren als reduzieren, und verbleiben daher unter Reaktionsbedingungen trivalent. Durch ihr hohes Oxidationspotential kommt es, vor allem für die Reaktion mit Isobutan, zur unerwünschten Totaloxidation des Reduktanden. Der Anteil isolierter Fe3+ Spezies korreliert mit der Aktivität der Katalysatoren für die SCR von NO und N2O. Weiterhin hängt zumindest für die Reaktion zwischen N2O und CO der Reaktionsmechanismus von der Art der vorliegenden Eisenspezies ab: an isolierten Plätzen erfolgt die Reduktion des N2O an dem an Fe3+ gebundenen CO. An FexOy-Clustern hingegen läuft die Reaktion als Redoxprozeß (Fe3+ / Fe2+) unter Bildung eines radikalischen Intermediates O-. Der Einfluß der Porengeometrie des Trägermaterials auf die katalytische Aktivität wurde an Katalysatoren mit ähnlichem Eisengehalt und ähnlicher Art und Verteilung der Eisenspezies studiert (Fe-MFI, Fe-SBA-15). Die drastisch höhere Aktivität von Fe-MFI belegt, daß die Lokalisierung der aktiven Komponente in einer Pore mit passender Geometrie (Größe und Struktur) essentiell für die katalytischen Eigenschaften ist. Als weitere, die Aktivität stark beeinflussen Größe, wurde für die Reaktion von NO mit Ammoniak und auch mit Isobutan die Azidität identifiziert, die jedoch für die katalytische Zersetzung oder Reduktion mit N2O keine Rolle spielt.The reduction of nitrogen oxides (NOx and N2O) was investigated over Fe-catalysts (Fe-MFI, Fe-beta and Fe-SBA-15) which were prepared by different methods have been analyzed by EPR and UV/VIS-DRS ex situ after synthesis, calcination and use in catalysis as well as in situ during calcination. It was found that aggregated species are formed at the expense of isolated Fe species upon calcination at 873 K, and that aggregate formation is slightly favored by calcination with higher heating rates as well as by high Si/Al ratio of the support. Use in SCR of NO leads to further growth and restructuring of FexOy clusters. These Fe-catalysts were studied by in situ EPR, in situ UV/VIS-DRS and in situ FT-IR spectroscopy during SCR of NO with NH3 or isobutane and during SCR of N2O with CO as well as during interaction with single feed components. The results were related to the catalytic behaviour. Different types of isolated Fe3+ sites with different reducibility were identified. Based on FT-IR results which revealed that NO reacts preferably with trivalent Fe, it is concluded that Fe3+ ions reduced under reaction conditions to Fe2+ do probably not contribute to catalytic activity. In general, the degree of steady-state Fe site reduction during NH3-SCR is markedly lower than during isobutane-SCR. This might be the reason for the lower activity of Fe-catalysts in the latter reaction. UV/VIS-DRS results suggest that isolated Fe3+ in octahedral coordination is easier reduced than tetrahedral Fe3+. In contrast to isolated Fe3+ species, FexOy clusters are much faster reoxidized than reduced and, thus, remain essentially trivalent under reaction conditions. Due to their higher oxidation potential, they cause undesired total oxidation of the reductant being much more severe in the case of isobutane. A correlation was found between the fraction of isolated Fe+3 sites in the catalysts and their activity for SCR of NO and N2O. The reaction mechanism of SCR of N2O with CO is Fe site dependent. Over isolated Fe sites, the reduction of N2O occurs via coordinated CO species on Fe3+ sites. The reaction over FexOy sites proceeds via a redox Fe3+/Fe2+ process with intermediate formation of O- radicals. The effect of pore geometry of the support on the catalytic activity was studied by comparing catalytic performance of Fe-MFI and Fe-SBA-15 which contain similar iron content and show similar nature and distribution of Fe species as evidenced by UV/VIS-DRS and EPR. Fe-MFI revealed to be much more active than Fe-SBA-15 in all reactions studied. This clearly illustrates that the confinement of the iron species in pores of suitable geometry (structure and size) is essential to originate their remarkable catalytic properties. Acidity is essential for SCR of NO with NH3 or isobutane but it is not mandatory for direct decomposition or SCR of N2O.
8
Lee, Cheng Chin, et 李承晉. « A study of practical applications of promoted decomposition of nitrogen oxide and sulfur dioxide via a module of electrochemical double-cell ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/82345255700790895938.
Texte intégralRésumé :
博士國立清華大學
化學工程學系
103
Because of the progress of technique of engine,there are more and more exhaust gas ,like NOx and SO2,discharged into the atmosphere. According to existing commercial technologies are no perfect way to deal with this different harmful compounds.Our group have developed the promoted nitrogen oxides decomposition technology since several years age and we made great achievements theoretically and experimentally. The use of electro-catalytic technology developed ceramic supported electrochemical double cell can handle nitrogen oxides and sulfur oxides at the same time.This study show that we can take advantage of the anode supported electrochemical double cell to treat NOx and SO2 greatly. Then,we scale up the double cell into electro-catalytic honeycomb(ECH) and use ECH to treat the exhaust gas of boiler and diesel engine.The result of the experiment show that the reaction rate of ECH can reach several times of reaction rate of SCR.This result demonstrate the potential to be applied to the industry.
9
« Preparation and characterization of NdSrCu1-xCoxO4 and SM1.8Ce0.2Cu1-xCoxO4 catalysts for NOx decomposition ». 2003. http://library.cuhk.edu.hk/record=b5891669.
Texte intégralRésumé :
Chan Yan Chi Rosa.Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references (leaves 70-71).
Abstracts in English and Chinese.
Abstract --- p.i
論文摘要 --- p.ii
Acknowledgements --- p.iii
Table of Contents --- p.iv
List of Tables --- p.vii
List of Figures --- p.viii
Chapter Chapter 1. --- Introduction
Chapter 1.1 --- Nitrogen oxides --- p.1
Chapter 1.1.1 --- NOx and their chemical and physical properties --- p.1
Chapter 1.1.2 --- Sources and formation of NOx --- p.3
Chapter 1.1.3 --- Evaluation of the impact of NOx on human health and environment --- p.4
Chapter 1.2 --- Decomposition of NOx --- p.5
Chapter 1.3 --- Perovskite-type oxides --- p.8
Chapter 1.3.1 --- Structure and composition of perovsite-type oxides --- p.8
Chapter 1.3.2 --- Preparation of perovskite-type oxides --- p.12
Chapter 1.3.3 --- Literature review of perovskites for NOx decomposition --- p.14
Chapter 1.4 --- Objective of the project --- p.16
References --- p.17
Chapter Chapter 2. --- Experimental
Chapter 2.1 --- Catalyst preparation --- p.20
Chapter 2.2 --- Catalytic activity evaluation --- p.20
Chapter 2.3 --- Catalyst characterization --- p.22
Chapter 2.3.1 --- Powder X-ray diffraction (XRD) --- p.22
Chapter 2.3.1.1 --- Theory --- p.22
Chapter 2.3.1.2 --- Instrumentation --- p.23
Chapter 2.3.2 --- "Brunauer, Emmett and Teller (BET)" --- p.26
Chapter 2.3.2.1 --- Theory --- p.26
Chapter 2.3.2.2 --- Experimental --- p.28
Chapter 2.3.3 --- X-ray photoelectron spectroscopy (XPS) --- p.28
Chapter 2.3.3.1 --- Theory --- p.29
Chapter 2.3.3.2 --- Qualitative and quantitative analysis --- p.29
Chapter 2.3.3.3 --- Instrumentation --- p.31
Chapter 2.3.4 --- Thermogravimetric analysis (TGA) --- p.34
Chapter 2.3.5 --- NO-temperature programmed desorption (NO-TPD) --- p.34
Chapter 2.3.6 --- Titration method --- p.35
References --- p.36
Chapter Chapter 3. --- Preparation and Characterization of NdSrCu1-xCox04 and Sm1.8Ceo.2Cu1-xCox04 catalysts for NOx Decomposition
Chapter 3.1 --- Introduction --- p.38
Chapter 3.2 --- Experimental --- p.39
Chapter 3.3 --- Results --- p.40
Chapter 3.3.1 --- "BET, XRD and chemical analysis studies" --- p.40
Chapter 3.3.2 --- Catalytic activity --- p.43
Chapter 3.3.3 --- XPS studies --- p.48
Chapter 3.3.4 --- TGA and NO-TPD --- p.57
Chapter 3.4 --- Discussion --- p.63
Chapter 3.4.1 --- Catalytic performance --- p.63
Chapter 3.4.2 --- Structural defects --- p.65
Chapter 3.4.3 --- Oxidation states --- p.67
Chapter 3.4.4 --- Copper ion redox ability --- p.68
References --- p.70
Chapter Chapter 4. --- Conclusion and Future Directions
Chapter 4.1 --- Conclusion --- p.72
Chapter 4.2 --- Future directions --- p.73
Chapter 4.2.1 --- Characterization of catalysts --- p.73
Chapter 4.2.2 --- Reaction mechanism --- p.73
Chapter 4.2.3 --- Variation of element in B-site --- p.74
10
Opoku, Michael Kwabena. « Co-recrystallisation, characterisation, and thermal analyses of ammonium nitrate based mixed salts : effect of additives on nitrogen oxides emissions ». Thesis, 2015. http://hdl.handle.net/1959.13/1314577.
Texte intégralRésumé :
Research Doctorate - Doctor of Philosophy (PhD)Ammonium nitrate remains a widely utilise ingredient in civil explosives, and fertilizers around the world. In civil explosive application, ammonium nitrate (AN) serves as a feedstock for making emulsion explosives as well as ammonium nitrate and fuel oil (ANFO) explosives, both commonly applied in open-cut mining operations. In recent years in Australia, demand for ammonium nitrate has increased significantly due to mining activities, the so called mining boom. However, the use of ammonium nitrate based explosives in civil applications may release orange clouds of nitrogen oxides under some condition of use and explosive formulations. Although AN-based explosives are formulated under stoichiometric compositions to produce only H₂O, CO₂, and N₂, in practice, CO, NO, and NO₂ gases are released when the formulation deviates from ideal conditions. Formation of carbon monoxide and nitrogen oxides poses risks to both people and the environment. In Australia, emissions of NOₓ (NO and NO₂) during blasting in mining operations have come under intense scrutiny by regulatory bodies and concerned citizens, as such emissions pose environmental and health risks; in particular, when orange clouds, characteristic of high levels of NO₂ and NO, do not dissipate rapidly and drift into populated areas surrounding the mines. Thus, there is a great interest in industries to find practical solutions to remedy the problems of NOₓ emissions from blasting of ammonium nitrate based explosives.
Chapitres de livres sur le sujet "Nitrogen oxide decomposition"
1
Almeida, Luis Eduardo Nunes, Aureomar F. Martins, Susane R. Gomes et Flavio A. L. Cunha. « Thermal Decomposition Kinetics Studies of HTPB/Al/AP Solid Propellants Formulated With Iron Oxide Burning Rate Catalyst in Nano and Micro Scale ». Dans Energetic Materials Research, Applications, and New Technologies, 211–33. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2903-3.ch010.
Texte intégralRésumé :
The thermal decomposition kinetics of ammonium perchlorate (AP)/hydroxyl-terminated-polybutadiene (HTPB) samples, with Iron Oxide catalyst at nano and micro scale were studied by thermal analysis techniques at different heating rates in dynamic nitrogen atmosphere. The exothermic reaction kinetics was studied by differential scanning calorimetry (DSC) in isothermal conditions. The Arrhenius kinetic parameters were obtained by Flynn-Wall and Ozawa Kissinger and Starink methods. The propellant samples thermal decomposition was studied simultaneously by TG-DTA. For this purpose, solid propellant grains containing nano and micro scale iron oxide were formulated. The effect of catalysts on the propellant burning rate and the propellant initiation sensitivity were also evaluated by friction and impact. The effect of the catalyst in the propellant binder reaction was evaluated by viscosity and mechanical properties. SEM/EDS technique was used to evaluate the iron oxide morphology. Three bench firing tests were performed with rockets motor in order to know the ballistics parameters.
2
Gutteridge, J. M. C. « Peroxynitrite damage to DNA ». Dans Experimental protocols for reactive oxygen and nitrogen species, 256. Oxford University PressOxford, 2000. http://dx.doi.org/10.1093/oso/9780198506683.003.0072.
Texte intégralRésumé :
Abstract Peroxynitrite (ONOO ) is a powerful oxidant formed by the reaction of superoxide with nitric oxide. Its decomposition at acid pH also gives rise to an aggressive oxidant with properties similar to those of the hydroxyl radical. When peroxynitrite oxidises a DNA base (2, 3) it leaves behind a nitrated footprint, such as 8-nitroguanine (1). The use of HPLC and GC-MS to profile base damage to DNA has been reviewed elsewhere (4).
3
Kobal, Ivan, Kazushi Kimura, Yuichi Ohno, Hideyuki Horino, Izabela Rzeznicka et Tatsuo Matsushima. « Nitrogen emission process in the decomposition of nitrogen oxides on Pd(11O) ; an angular and velocity distribution study ». Dans Studies in Surface Science and Catalysis, 1337–42. Elsevier, 2000. http://dx.doi.org/10.1016/s0167-2991(00)80385-7.
Texte intégral
4
Russo, Roberta, Maria Acanfora, Tommaso Coppola et Luca Micoli. « Technical Feasibility Study of an Ammonia-Fuelled Mega-Yacht Powered by PEM Fuel Cells ». Dans Progress in Marine Science and Technology. IOS Press, 2022. http://dx.doi.org/10.3233/pmst220049.
Texte intégralRésumé :
The maritime sector forecasts that ammonia will play a pivotal role in decarbonizing ships since it does not emit carbon dioxide (CO2). Nevertheless, burning ammonia in ICE produces nitrogen oxides (NO2 and N2O), which are GHG more dangerous than CO2. The use of Proton Exchange Membrane Fuel Cell (PEM) systems instead of ICE avoids the emissions of harmful compounds. In this study, a PEM system is considered for the electric power generation onboard a 63 m length mega-yacht, replacing a traditional MGO gen-set. The pure hydrogen required for fuelling the PEM is produced through an ammonia decomposition reactor and a purification system, to be installed onboard as well. It results that an ammonia processing system for generating hydrogen requires additional power, in this case study is in the range of 360–475 kWe, and it is heavier and bulkier than the gen-set. Despite these cons, its installation onboard seems to be feasible and it does not involve significant modifications to the original configuration of the mega-yacht. The ammonia-fuelled mega-yacht reduces the original duration of navigation from 11 to about 5 days, nevertheless, this value appears still adequate considering the innovative solution at zero-emission proposed.
5
Calvert, Jack G., John J. Orlando, William R. Stockwell et Timothy J. Wallington. « Chemical Mechanisms for Air Quality Modeling and Their Applications ». Dans The Mechanisms of Reactions Influencing Atmospheric Ozone. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190233020.003.0012.
Texte intégralRésumé :
A chemical mechanism is a critical component of an air quality model. Tropospheric gas phase chemical mechanisms for air quality modeling are designed to simulate the production of ozone, acids, and aerosol precursors. Therefore, their focus is on the oxidation chemistry of ozone, nitrogen oxides, sulfur compounds, and organic compounds. Figure IX-A-1 is an overview of the most important cycles of radicals that must be represented in a chemical mechanism for air quality modeling. The processes shown schematically on one level may appear to be relatively simple, but, in reality, the chemical mechanism is extremely complicated due to the very large number of organic compounds present in the atmosphere. Atmospheric chemistry mechanisms are based on laboratory data and tested against environmental experiments and field measurements (Stockwell et al., 2012). Usually, the mechanism is considered to consist of chemical species and their reactions and rate coefficients, along with the photochemical data (used to calculate photolysis frequencies). An atmospheric chemical mechanism employed in an air quality model could be considered to include the rules for aggregating emissions and initial concentrations into species (Middleton et al., 1990). There are many thousands of volatile organic compounds (VOCs) emitted into the atmosphere, and each has its own decomposition mechanism that determines the effect of the VOC on ozone production. It is critical for a chemical mechanism to characterize the chemistry of the VOCs and their differences in chemical reactivity as accurately as possible. Middleton et al. (1990) pointed out that air quality models have only a limited number of species compared to emission inventories. An emissions aggregation scheme is the process of mapping a detailed emissions inventory into the limited number of species used in an air quality model. The scheme is an important component of any model chemical mechanism. Middleton et al. published their aggregation process for the mechanism used in the Regional Acid Deposition Model (RADM2, Stockwell et al., 1990), but, too often, the emissions aggregation scheme for a given chemical mechanism is in the gray literature and difficult to access.
6
Keefer, Robert F. « Parts of a Soil (Soil Constituents) Air, Water, Minerals, and Organic Matter ». Dans Handbook of Soils for Landscape Architects. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195121025.003.0005.
Texte intégralRésumé :
Soils physically consist of soil solids and pore space. Soil solids are composed of (a) mineral matter such as sand (coarse particles), silt (fine particles), and clay (very fine particles), and (b) soil organic matter, like decaying plant, animal, and microbial remains, along with microbial synthates. The pore space is occupied by soil air and soil water, each of which has a different makeup than atmospheric air and rainwater. Soil air often has more carbon dioxide and gases of nitrogen and sulfur compounds. Soil water has much more dissolved substances in it than rainwater. Soil solids occupy about 50% of a soil. They are made up of about 45% mineral matter and about 5% organic matter, but these proportions vary greatly. Soil mineral matter consists of very coarse rocks (primary minerals) and the three main soil parts: . . . 1. Coarse—Sand (a primary mineral, silicon dioxide) 2. Fine—Silts (both primary or secondary minerals) 3. Very Fine—Clays (secondary minerals) . . . Soil organic matter consists of plant and animal remains (in various stages of decomposition), microorganisms, and compounds synthesized by microorganisms. Soil pore space occupies about 50% of a soil and consists of the open space occupied by either air or water. The proportions of air and water that are present can greatly influence plant growth. Soil air is necessary for plants to grow, but if this component dominates, drought occurs and plant growth suffers. Soil water is also necessary for plant growth, but if this component dominates, flooding occurs and plant growth also suffers as most plants require a supply of oxygen. Soil consists of natural elements, for example, Si, Al, Fe, Ca, Mg, Na, K, Ti, P, and others. Often the elements are present in oxides, sulfides, silicates, and other combinations. These elements or their combined form are present as rocks (primary minerals), clays (secondary minerals), and available nutrients for plants. Soil contains many life forms.
7
Kushnerenko, Vladyslav, et Andrey Andreychenko. « GREENING OF INDUSTRIAL POULTRY TERRITORIES AS ONE OF THE WAYS OF REDUCING THE NEGATIVE IMPACT ON THE ENVIRONMENT ». Dans Traditions and new scientific strategies in the context of global transformation of society. Publishing House “Baltija Publishing”, 2024. http://dx.doi.org/10.30525/978-9934-26-406-1-7.
Texte intégralRésumé :
In the area of operation of large poultry farms, atmospheric air can be polluted by microorganisms, dust, bad organic compounds that are products of decomposition of organic waste, as well as oxides of nitrogen, sulfur, and carbon. The epizootic process in conditions of intensive poultry farming is distinguished by the fact that even weakly virulent and conditionally pathogenic microflora, as a result of recirculation and frequent changes of generations, can increase virulence properties and create a serious epizootic and epidemiological threat. The purpose of the work is to demonstrate greening of industrial poultry farms as one of the ways to reduce the negative impact on the natural environment. The presented material in the work: systematization of achievements in theory and practical application of green plantings to prevent environmental pollution using various options for improving the territories of poultry enterprises. The research methodology is based on general research methods of analysis and synthesis, induction and deduction, observation and abstraction, which systematize the achievements of the theory and practice of modeling systems of various nature in the natural sciences and, in particular, in animal husbandry and plant breeding. As a result of research and experiments, the expediency and effectiveness of using green plantings, which have a great deodorizing ability – retain and absorb gases, have been theoretically and practically substantiated. The positive effect of greenery on physiological indicators (thermoregulation, oxidation processes) and animal productivity has been practically established. The dustiness of the air under the trees is less than in the open area: in May by 20%, in June by 21.8%, in July by 34.1%, in August by 27.7% and in September by 38.7%. During the entire growing season, the average concentration of dust in the open area was 0.9 mg/m3 of air, and under trees – 0.52 mg/m3 of air, i.e. 42.2% less. The most gas-resistant trees and shrubs are: Pennsylvania maple, sycamore, Manchurian hazel, three-spined gorse, gooseberry (all species), common ivy, Cossack juniper, Canadian and Daur moonseed, large-leaved poplar, gray poplar, Canadian poplar, pomegranate, ailant the highest, white acacia, amorphous shrub, pinnate birch, common privet, white mulberry. By alternating plantations with open areas around the places of emission of harmful gases, it is possible to significantly increase the ventilation of the territory in the vertical direction. In a hot climate, green spaces provide protection from dry and dusty winds and at the same time contribute to airing the territory of the enterprise, cleaning its atmosphere from harmful pollutants. Value/originality. The effectiveness of the proposed method of preventing environmental pollution provides new opportunities for poultry enterprises in the preservation of ecosystems and sustainable development of territories. Measures for the protection of atmospheric air should be carried out on the basis of widely distributed research works devoted to the study of the quantitative concentration of pollutants entering the atmosphere and the distance of their spread.
Actes de conférences sur le sujet "Nitrogen oxide decomposition"
1
Kim, Kwan-Tae, Sungkwon Jo, Hee Seok Kang, DaeHoon Lee et Young-Hoon Song. « Preliminary study for plasma-catalytic decomposition of nitrogen oxide ». Dans 2016 IEEE International Conference on Plasma Science (ICOPS). IEEE, 2016. http://dx.doi.org/10.1109/plasma.2016.7534029.
Texte intégral
2
Zang, Yuwei, et Qin Zhong. « Nitrogen Oxide Decomposition on Cerium Modified ZSM-5 Zeolite in the Presence of Oxygen ». Dans 2009 International Conference on Energy and Environment Technology (ICEET 2009). IEEE, 2009. http://dx.doi.org/10.1109/iceet.2009.564.
Texte intégral
3
Seong, B. G., S. Y. Hwang et J. M. Park. « Sialon Coating from Sintered Mixtures of Silicon Nitride and Oxides ». Dans ITSC2003, sous la direction de Basil R. Marple et Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p0719.
Texte intégralRésumé :
Abstract Silicon nitride and sialons are very attractive materials for thermal spaying, but the high temperatures of spray processes lead to their decomposition instead of melting. Therefore, the use of these materials as protective coatings has been very restricted. Nevertheless, researchers have tried to provide silicon nitride-based coatings using metallic or oxide binders. Oxide binder additions to silicon nitride have been quite successful. In this paper, mixtures of silicon nitride and oxides were prepared for the thermal spraying of silicon nitride-based materials by using a detonation gun. Powders for the spraying were prepared through mixing, sintering, crushing and sieving. To get an oxide binder of low melting point, three components of oxides, Al2O3-ZrO2-TiO2, were selected; the ratio of oxides was determined to have a low melting point. When the sintering temperatures were below 1400°C, phases of the powders and coating layers were composed of α-Si3N4 and oxides and any of sialon phases were not found. By sintering at the temperatures between 1400 and 1600°C in a nitrogen gas environment, χ(chi)-sialon (Si6Al10O21N4) and β’-sialon (Si3Al3O3N5) were formed. The ratio of β’-sialon increased as the sintering temperature increased. TiO2 was transformed to a nitride, TiN. During the spraying procedure χ-sialon was decomposed to amorphous binder, but β’-sialon was not totally decomposed. Finally a coating layer composed of tetragonal-zirconia and β’-sialon was made.
4
Zimmerman, A., C. Tissera, E. Tatli, N. Clark, R. Atkinson, G. Thompson et R. Turton. « System Model for Selective NOx Recirculation (SNR) to be Used in Stationary Lean-Burn Natural Gas Engines ». Dans ASME 2006 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/icef2006-1542.
Texte intégralRésumé :
A model for a possible system to implement Selective NOx Recirculation (SNR) technology for stationary lean-burn natural gas engines was developed. SNR is a NOx (NOx includes the various oxides of nitrogen found in an exhaust stream) removal after-treatment technology with four phases; cooling the hot exhaust gas, NOx adsorption onto a sorbent material, periodic NOx desorption using heat, and NOx decomposition within the combustion process. This paper presents the model, summarizes the research used to develop the model, and presents model output. NOx decomposition in the combustion process was investigated by injecting nitric oxide (NO) into the intake of a Cummins L10G natural gas fueled spark-ignited engine (210 kW at 2100 rpm). Experimental campaigns were conducted during lean-burn and rich-burn operation to quantify in-cylinder NOx decomposition. Data previously published suggest that rich burn is essential for adequate NOx decomposition and that lean burn was ineffective. The NOx adsorption/desorption characteristics of the sorbent material were quantified using a bench top adsorption system equipped with four thermocouples, an in-line heater, a mass flow controller and a Rosemont Analytical NOx analyzer. The sorbent chamber was filled with activated carbon sorbent material. Extensive testing of the adsorption characteristics using 500 ppm NO (balance nitrogen) from a pressure tank yielded a mass percent of .0005 NO to carbon. These results suggested that unacceptably large adsorbers would be needed in industrial applications. However, further measurement using real exhaust showed a loading of 0.65 mass percent of NO to carbon. The presence of oxygen and water are implicated in this improved adsorption. This scaled system considered the heating rates (for desorption) and cooling rates (for adsorption) for the bed at the time when desorption and adsorption processes were initiated. An adsorption/desorption model that considered gas temperature and heat and mass transfer was formulated based on these data. A simplified linear driving force model was developed to predict NOx adsorption into the sorbent material as cooled exhaust passed over fresh sorbent material.
5
Engblom, Markus, Pia Kilpinen, Fredrik Klingstedt, Kari Era¨nen et Ranjit Katam Kumar. « NOx and N2O Emission Formation Tendency From Multifuel CFB-Boilers : A Further Development of the Predictor ». Dans 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78116.
Texte intégralRésumé :
Present paper is a part of our on-going model development activities with aim to predict formation tendency of gaseous emissions from CFB combustion of different fuels, and especially, fuel-mixtures in real furnaces of various scale. The model is based on detailed description of homogeneous, catalytic, and heterogeneous chemical kinetics, and a sound but simple 1.5D representation of fluid dynamics. Temperature distribution is assumed known. With the tool, different fuels and fuel mixtures can be compared in respect to their tendency to form nitrogen oxides (NOx, N2O). In this paper the model was tested to predict nitrogen oxide emissions from mono- or co-combustion of coal, wood, and sludge. The plants simulated were the 12MWth CFB combustor located at Chalmers Technical University (A = 2.25m2, h = 13.6m) and the pilot scale CFB unit at the Technical University Hamburg-Harburg (d = 0.1m, h = 15m). The results gave reasonable representation of the measured emission data, and reflected correctly to the changes in the fuel characteristics and in the furnace operating conditions in most cases. An extensive laboratory fixed-bed reactor study was also performed in order to obtain input values for the kinetic constants of the catalytic reactions for the reduction and decomposition of nitrogen oxides. In literature, there is a limited data available regarding the catalytic activity of CFB solids during combustion of wood- and waste-derived fuels, especially at co-firing conditions. The kinetics for the NO reduction by CO in the temperature range of 780–910°C was determined to be of the following form (NO = 300ppm, CO = 5000ppm): −rNO=k·[NO]0.48·[CO]0.55mol/g-s with k=8.15·exp(−8869/T)m3/kg-s(emptyreactoreffectincluded)ork=830·exp(−14930/T)(emptyreactoreffectexcluded), when using a bed sample (250–355 μm) taken from the transport zone in the CTH boiler while burning a mixture of wood pellets and a pre-dried municipal sewage sludge. The role of char particle size and shape as well as the incorporation of energy balance on the char reactivity and the formation of nitrogen oxides is further illustrated by single char particle oxidation simulations.
6
Bharadwaj, Lavanya, Abhijeet Dhamne, Linan An, Barry Fookes, Jay Kapat et Louis Chow. « Polymer-Derived Si-Al-C-N-O Ceramics for High Temperature Applications ». Dans ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38561.
Texte intégralRésumé :
Polymer-derived ceramics are a new class of materials synthesized by thermal decomposition of polymeric precursors. The resultant materials are amorphous alloys of silicon, carbon, and nitrogen, which can be converted to crystalline materials by annealing at higher temperatures. This novel chemical-to-ceramic route offers a unique opportunity to tailor the structures and compositions, therefore the properties, of the resultant materials by designing the chemistry of the precursors. In this paper we report the studies on synthesis and oxidation behavior of polymer-derived SiAlCN materials. The precursor was synthesized by mixing a polysilazane and aluminum isopropoxide. The mixture was then pyrolyzed at 1000°C in Ar/N2 to convert to SiAlCNO ceramics. The oxidation studies revealed that the SiAlCNO possesses a lower oxidation rate than SiCN. It is believed that the better oxidation resistance exhibited by SiAlCN is due to the oxide layer containing Al, which makes oxygen diffusion more difficult than in pure SiO2. The materials are promising for many high temperature applications, e.g. environmental barrier coatings, high temperature fibers, matrixes for composites, and even monolithic components.
7
Tang, Sheng-Yi, et Yu-Hao Hu. « Investigation on Nitrogen Oxides Decomposition System ». Dans 2021 IEEE 3rd Eurasia Conference on IOT, Communication and Engineering (ECICE). IEEE, 2021. http://dx.doi.org/10.1109/ecice52819.2021.9645635.
Texte intégral
8
White, B. D., O. Kesler, N. Ben-Oved et A. Burgess. « Preparation of an SOFC LSM/YSZ Composite Cathode by Air Plasma Spraying ». Dans ITSC2006, sous la direction de B. R. Marple, M. M. Hyland, Y. C. Lau, R. S. Lima et J. Voyer. ASM International, 2006. http://dx.doi.org/10.31399/asm.cp.itsc2006p0827.
Texte intégralRésumé :
Abstract A porous composite cathode containing (La0.8Sr0.2)0.98MnO3 (LSM) and yttria stabilized zirconia (YSZ) for use in a solid oxide fuel cell has been produced by air plasma spraying. Deposition was carried out using axial powder injection for increased deposition efficiency and composition control. A plasma composed of argon and nitrogen was used to decrease processing costs and avoid decomposition of the cathode material during deposition. Preliminary investigations focused on determining the range of plasma conditions under which each of the materials could be successfully deposited separately. A set of conditions was thereby determined that were suitable for the deposition of a composite cathode from pre-mixed LSM and YSZ powders. Graphite pore former was added to the powder mixture in order to achieve sufficient porosity in the final coating. A tape cast YSZ electrolyte was used as the substrate for the deposition of the cathode and also as the mechanical support layer in the finished cell. Following deposition of the cathode, an anode was produced by traditional wet ceramic processing techniques. Plasma sprayed cathode was characterized by SEM, EDX, and XRD, and the electrochemical performance of the full fuel cell was evaluated.
9
Shahien, M., M. Yamada et M. Fukumoto. « Reactive Plasma Sprayed Nitride Coatings with Improved Conductivity ». Dans ITSC2017, sous la direction de A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen et C. A. Widener. DVS Media GmbH, 2017. http://dx.doi.org/10.31399/asm.cp.itsc2017p0934.
Texte intégralRésumé :
Abstract Decomposition of the nitride ceramic particles like aluminium nitride (AlN) during conventional thermal spray process prevents their deposition on the substrate. Reactive plasma spraying (RPS) is a promising solution to fabricate AlN coatings. It is based on reaction and deposition of molten particles in active nitrogen ambient to form the AlN phase. Several thick AlN based coatings were fabricate successfully by reactive plasma spraying of aluminium and/or alumina particles. This study shows our recent achievements of fabrication of AlN coatings with improved conductivity. It was possible to fabricate AlN based coatings through reactive spraying of fine alumina particles mixed with fine AlN additives. Using small particle size powders improved the particles melting, surface area, therefore nitriding conversion and the AlN content. The fabricated AlN based coating contains several of oxide phases, with low density and high porosity, therefore its thermal conductivity was very low (about 2.6 W/m.K). To fabricate AlN coatings with high thermal conductivity, a liquid phase promoting additive (yttria) was added to the feedstock powder. It assists the formation of the yttrium aluminate (Y-Al-O) phase and therefore the sintering of the coatings during heat treatment. Finally, AlN coating with improved thermal conductivity (above 90 W/m.K) was developed.
10
Toma, F. L., G. Bertrand, D. Klein, C. Coddet et C. Meunier. « Photocatalytic Decomposition of Nitrogen Oxides Over TiO2 Coatings Elaborated by Liquid Feedstock Plasma Spraying ». Dans ITSC2005, sous la direction de E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p0476.
Texte intégralRésumé :
Abstract In this paper, the modified method of plasma spraying using liquid suspension feedstock was used to elaborate thin titanium dioxide coatings. TiO2 Degussa P25 powder were dispersed by continuous stirring in distilled water and alcoholic solutions and injected in an Ar-H2 or Ar-H2-He plasma plume under atmospheric conditions. Scanning electron microscopy and X-ray diffraction were performed to study the microstructure and crystalline phases of titanium dioxide coatings. The anatase content in the elaborated TiO2 deposits strongly depended on the type of the suspension solvent. The photocatalytic activity of the titanium dioxide coatings was evaluated from the conversion rate of nitrogen oxides and compared with that of the initial powder. The obtained results allowed to affirm that the method of the liquid plasma spraying proved to be a promising technique to elaborate photocatalytic TiO2 coatings for the removal of nitrogen oxides pollutants.
Rapports d'organisations sur le sujet "Nitrogen oxide decomposition"
1
MECHANISTIC STUDIES AND DESIGN OF HIGHLY ACTIVE CUPRATE CATALYSTS FOR THE DIRECT DECOMPOSITION AND SELECTIVE REDUCTION OF NITRIC OXIDE AND HYDROCARBONS TO NITROGEN FOR ABATEMENT OF STACK EMISSIONS. Office of Scientific and Technical Information (OSTI), avril 1998. http://dx.doi.org/10.2172/9059.
Texte intégral