Tesi sul tema "Ammoniac (NH3)"
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Aroui, Hassen. "Transferts rotationnels induits par collisions dans les systèmes NH3-H2 et NH3-He". Paris 11, 1989. http://www.theses.fr/1989PA112214.
Testo completoWe have studied rotational transfer induced by inelastic collision in NH₃perturbed by Hz and He. Their systems have astrophysical and fundamental interests. We have undertaken this study by using two methods: 1) Absorption line-profiles in the infrared. 2) Time resolved infrared-infrared double resonance. The first one allowed to determine pressure broadening (PB) cross sections and intradoublet cross relaxation (CR) cross sections caused by molecular inversion. These last ones are very sensitive to the detail of intermolecular potential. These measurements were done as a function of the rotational quantum number j and the temperature in both range of the v₄ band and of the vibrational ground state. Because of the difference between results obtained in the v₄ band and in the microwave, and in order to obtain a better comparison between measurements and calculations, we have studied the absorption line-profiles in the vibrational ground state. The main results lead to the following conclusions: - PB cross section increases with the vibrational quantum number the NH₃ - He one. - PB cross section for NH₃- H₂ para system are larger than the NH₃ - He one. - It is necessary to take the rotational excitation of H₂ into account. - Good agreement has been obtained between calculated (using a semi-classical method) and measurements for NH₃ - H₂ system. The only remaining discrepancy between theory and experience is then intradoublet CR cross section for the NH₃ - He system; we think that this could be caused by inaccuracies in the NH₃ - He potential. The second method, which is a very sensitive mean to study rotational transfer induced by inelastic collision, consist of pumping the v₂ band of NH₃ with an infrared pulse TEHP C0₂ laser in order to create a non-equilibrium population in specific rotational quantum state. This state as well as others subsequently populated by collision induced transition is monitored by diode laser tuned on the v₄ band. This study permit to determine the inelastic cross-section for every level and the collisional selection rules
Sagui, Kenneth. "Représentation analytique globale de la surface de potentiel de la molécule NH3 dans son état électronique fondamental". Université de Marne-la-Vallée, 2006. http://www.theses.fr/2006MARN0315.
Testo completoCaville, Sylvain. "Spectroscopie embarquée pour la distribution verticale d'ammoniac (NH3) et de dioxyde de carbone (CO2)". Electronic Thesis or Diss., Reims, 2024. http://www.theses.fr/2024REIMS008.
Testo completoAmmonia (NH3) is an atmospheric pollutant, emitted at 80 % by agriculture, which contributes to the eutrophication and acidification of natural environments. It is also a precursor of fine particles (PM2.5) that are harmful to human health. Despite this major scientific and societal role, our knowledge about atmospheric ammonia is still very limited. Measuring the vertical profile of NH3 is one of the keys to improving this knowledge. For this reason, the main objective of this thesis is to develop an ammonia measurement instrument that can be embedded in a tethered balloon to measure these vertical profiles. To begin, a state of the art of NH3 measurement was carried out through the data analysis of the AMICA campaign (Multi-Instrumental Analysis of Ammonia Concentrations) in autumn 2021. It highlighted the need to design an instrument without a sampling system to avoid bias due to NH3 adsorption. To assess the infrared spectroscopy techniques (DAS and WMS) intended for NH3 detection, a first instrument aimed at atmospheric CO2 measurements (main anthropogenic greenhouse gas) was developed and used to carry out vertical profiles. As NH3 is much more difficult to detect than CO2 , a long-path optical cell was designed to improve the instrument’s sensitivity. On a more general level, the tools developed and implemented during this thesis can be applied to the measurement of all the atmospheric species of interest, and in particular those that exist in trace quantities
Maaroufi, Nourhene. "Détermination des paramètres spectroscopiques des bandes v1 et v3 de NH3 par spectroscopie infrarouge". Electronic Thesis or Diss., Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCC099.
Testo completoThe aim of this work was to determine the parameters of the absorption lines of the ammonia molecule for atmospheric applications. In this regard, we measured, at room temperature, the intensities, the broadening and the shift coefficients of the lines of the bands v1, v3, 2v4, and 4v2 in the spectral region 3050-3600 cm-1 of self-disturbed NH3. These measurements were carried out in a large number of branches of these bands with very high precision using a high resolution Fourier transform infrared spectrometer (0.008 cm-1).These spectroscopic parameters were determined using a multi-pressure fitting technique using two different profiles: a Voigt profile and a Rosenkranz profile.The manuscript consists of five parts. The first part concerns the spectroscopic properties of ammonia. The second part is dedicated to the apparatus, with the description of the Bruker IFS125HR IRTF spectrometer. In the third part, we expose the results of the line intensities and self-broadenings of isolated lines, which are extracted from the recorded spectra, bands v1, v3, 2v4 and 4v2 of NH3. The fourth part presents the results obtained on line shifts and the interference effects between the components of the doublets of the v1 and v3 bands of NH3.To interpret the results of the line width measurements of the self-disturbed NH3 collisional system, we will present in chapter 5 the formalism adopted for the calculation of these widths. A comparison between the calculated and measured widths makes it possible to test the validity of the formalism used
Peyrovi, Parnian. "Improved resistance to deactivation of coupled NH3-SCR/ DPF catalyst for diesel exhaust emissions control". Thesis, Lille, 2018. http://www.theses.fr/2018LIL1R041.
Testo completoDiesel engines have been extensively implemented because they emit lesser CO2 than gasoline engine of equivalent power, since they work in lean condition, i.e. in excess of oxygen. Recently, Selective Catalytic Reduction (SCR) catalysts coated on Diesel Particulate Filters (DPF) have been introduced for automotive applications due to capability of reducing NOx and PM simultaneously. However, such implementation requires improved thermal resistance of the SCR catalyst due to the exotherms related to the periodic regeneration of DPF. The point of this manuscript is to propose a catalyst active in NOx reduction by NH3 after aging at high temperature. The first part of this manuscript details the modifications of CeV0.95W0.05O4 catalyst by adding of rare earths elements (Pr3+, Gd3+, Tb3+, and Er3+). The most promising catalyst obtained by the partial substitution of cerium by rare earths was finally Ce0.5Er0.5V0.95W0.05O4 catalyst. A partial substitution of the cerium by the erbium allows obtaining an increase of the activity after an aging at 600°C and 850°C attributed to the ability of erbium to promote thermal stability of the vanadium-containing catalysts. This behaviour might be also correlated with the characteristics of Er3+_O_V5+ bond and to their ability to alter the characteristics of the V_O bond and the acid/base surface properties. Ce0.5Er0.5V0.95W0.05O4 catalyst, an optimized formulation, is able to get a NOx conversion superior to 80% between 250 and 400°C in Fast-SCR condition after an aging at 850°C
Peyrovi, Parnian. "Improved resistance to deactivation of coupled NH3-SCR/ DPF catalyst for diesel exhaust emissions control". Electronic Thesis or Diss., Université de Lille (2018-2021), 2018. http://www.theses.fr/2018LILUR041.
Testo completoDiesel engines have been extensively implemented because they emit lesser CO2 than gasoline engine of equivalent power, since they work in lean condition, i.e. in excess of oxygen. Recently, Selective Catalytic Reduction (SCR) catalysts coated on Diesel Particulate Filters (DPF) have been introduced for automotive applications due to capability of reducing NOx and PM simultaneously. However, such implementation requires improved thermal resistance of the SCR catalyst due to the exotherms related to the periodic regeneration of DPF. The point of this manuscript is to propose a catalyst active in NOx reduction by NH3 after aging at high temperature. The first part of this manuscript details the modifications of CeV0.95W0.05O4 catalyst by adding of rare earths elements (Pr3+, Gd3+, Tb3+, and Er3+). The most promising catalyst obtained by the partial substitution of cerium by rare earths was finally Ce0.5Er0.5V0.95W0.05O4 catalyst. A partial substitution of the cerium by the erbium allows obtaining an increase of the activity after an aging at 600°C and 850°C attributed to the ability of erbium to promote thermal stability of the vanadium-containing catalysts. This behaviour might be also correlated with the characteristics of Er3+_O_V5+ bond and to their ability to alter the characteristics of the V_O bond and the acid/base surface properties. Ce0.5Er0.5V0.95W0.05O4 catalyst, an optimized formulation, is able to get a NOx conversion superior to 80% between 250 and 400°C in Fast-SCR condition after an aging at 850°C
Boumaraf, Latra. "Etude des réactions chimiques dans les ammoniacates solides : application du système BaCl2/NH3 à la réfrigération solaire". Grenoble INPG, 1989. http://www.theses.fr/1989INPG0026.
Testo completoMehsein, Kawsar. "Degradation mechanisms study of NOx after-treatment SCR system using urea on a Diesel Particulate Filter catalyst". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2017. http://www.theses.fr/2017ENCM0012.
Testo completoThe selective catalytic reduction (SCR) by urea or ammonia is a well-known method to meet the European emission regulation requirements concerning the reduction of nitrogen oxides (NOx) emissions from Diesel engines. In order to optimize the NOx reduction activity at all temperature range, a copper-exchanged zeolite (Cu-Zeolite) SCR catalyst is combined to a Diesel Particulate Filter (SCRF). However, during the continuous regeneration of the particulate filter, the SCRF catalyst will go through numerous constraints such as variable high temperature, poisoning compounds from Diesel fuel and engine oil, during the entire vehicle life of the after-treatment line. Moreover, the European legislation requires a durability of the after-treatment line for about 160,000km. Understanding the degradation of the SCRF catalyst by the hydrothermal ageing is of interest to apprehend the deactivation mechanism in order to develop a stable material. In the present work, accelerated hydrothermal ageing in laboratory oven and also a real driving ageing of an SCRF catalyst, included in an after-treatment line for about 120,000km, were performed. The different results obtained help to apprehend the degradation mechanism of a Cu-Zeolite SCRF catalyst performance and also to find a correlation between a 120,000km real driving ageing and an equivalence oven aged SCRF catalysts. Moreover, rapid characterization methods, to detect the hydrothermal ageing status of an SCRF catalyst, have been selected. Finally, a mathematical model, based on experimental results, has allowed to describe the degradation of the ammonia storage capacity of the SCRF catalyst with the hydrothermal ageing
Van, Damme Martin. "Assessment of global atmospheric ammonia using IASI infrared satellite observations". Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209085.
Testo completoThe natural nitrogen cycle has been and is significantly perturbed by anthropogenic emissions of reactive nitrogen (Nr) compounds into the atmosphere, resulting from our production of energy and food. In the last century global ammonia (NH3) emissions have doubled and represent nowadays more than half of total the Nr emissions. NH3 is also the principal atmospheric base in the atmosphere and rapidly forms aerosols by reaction with acids. It is therefore a species of high relevance for the Earth's environment, climate and human health (Chapter 1). As a short-lived species, NH3 is highly variable in time and space, and while ground based measurements are possible, they are sparse and their spatial coverage is largely heterogeneous. Consequently, global spatial and temporal patterns of NH3 emissions are poorly understood and account for the largest uncertainties in the nitrogen cycle. The aim of this work is to assess distributions and saptiotemporal variability of NH3 using satellite measurements to improve our understanding of its contribution to the global nitrogen cycle and its related effects.
Recently, satellite instruments have demonstrated their abilities to measure NH3 and to supplement the sparse surface measuring network by providing global total columns daily. The Infrared Atmospheric Sounding Interferometer (IASI), on board MetOp platforms, is measuring NH3 at a high spatiotemporal resolution. IASI circles the Earth in a polar Sun-synchronous orbit, covering the globe twice a day with a circular pixel size of 12km diameter at nadir and with overpass times at 9:30 and 21:30 (local solar time when crossing the equator). An improved retrieval scheme based on the calculation of Hyperspectral Range Index (HRI) is detailed in Chapter 2 and compared with previous retrieval methods. This approach fully exploits the hyperspectral nature of IASI by using a broader spectral range (800-1200 cm-1) where NH3 is optically active. It allows retrieving total columns from IASI spectra globally and twice a day without large computational resources and with an improved detection limit. More specifically the retrieval procedure involves two steps: the calculation of a dimensionless spectral index (HRI) and the conversion of this index into NH3 total columns using look-up tables (LUTs) built from forward radiative transfer simulations under various atmospheric conditions. The retrieval also includes an error characterization of the retrieved column, which is of utmost importance for further analysis and comparisons. Global distributions using five years of data (1 November 2007 to 31 October 2012) from IASI/MetOp-A are presented and analyzed separately for the morning and evening overpasses. The advantage of the HRI-based retrieval scheme over other methods, in particular to identify smaller emission sources and transport patterns over the oceans is shown. The benefit of the high spatial sampling and resolution of IASI is highlighted with the regional distribution over China and the first four-year time series are briefly discussed.
We evaluate four years (1 January 2008 to 31 December 2011) of IASI-NH3 columns from the morning observations and of LOTOS-EUROS model simulations over Europe and Western Russia. We describe the methodology applied to account for the variable retrieval sensitivity of IASI measurements in Chapter 3. The four year mean distributions highlight three main agricultural hotspots in Europe: The Po Valley, the continental part of Northwestern Europe, and the Ebro Valley. A general good agreement between IASI and LOTOS-EUROS is shown, not only over source regions but also over remote areas and over seas when transport is observed. The yearly analyses reveal that, on average, the measured NH3 columns are higher than the modeled ones. Large discrepancies are observed over industrial areas in Eastern Europe and Russia pointing to underestimated if not missing emissions in the underlying inventories. For the three hotspots areas, we show that the seasonality between IASI and LOTOS-EUROS matches when the sensitivity of the satellite measurements is taken into account. The best agreement is found in the Netherlands, both in magnitude and timing, most likely as the fixed emission timing pattern was determined from experimental data sets from this country. Moreover, comparisons of the daily time series indicate that although the dynamic of the model is in reasonable agreement with the measurements, the model may suffer from a possible misrepresentation of emission timing and magnitude. Overall, the distinct temporal patterns observed for the three sites underline the need for improved timing of emissions. Finally, the study of the Russian fires event of 2010 shows that NH3 modeled plumes are not enough dispersed, which is confirmed with a comparison using in situ measurements.
Chapter 4 describes the comparisons of IASI-NH3 measurements with several independent ground-based and airborne data sets. Even though the in situ data are sparse, we show that the yearly distributions are broadly consistent. For the monthly analyzes we use ground-based measurements in Europe, China and Africa. Overall, IASI-derived concentrations are in fair agreement but are also characterized by less variability. Statistically significant correlations are found for several sites, but low slopes and high intercepts are calculated in all cases. At least three reasons can explain this: (1) the lack of representativity of the point surface measurement for the large IASI pixel, (2) the use of a single profile shape in the retrieval scheme over land, which does therefore not account for a varying boundary layer height, (3) the impact of the averaging procedure applied to satellite measurements to obtain a consistent quantity to compare with the in situ monthly data. The use of hourly surface measurements and of airborne data sets allows assessing IASI individual observations. Much higher correlation coefficients are found in particular when comparing IASI-derived volume mixing ratio with vertically resolved measurements performed from the NOAA WP-3D airplane during CalNex campaign in 2010. The results demonstrate the need, for validation of the satellite columns, of measurements performed at various altitudes and covering a large part of the satellite footprint.
The six-year of IASI observations available at the end of this thesis are used to analyze regional time series for the first time (Chapter 5). More precisely, we use the IASI measurements over that period (1 January 2008 to 31 December 2013) to identify seasonal patterns and inter-annual variability at subcontinental scale. This is achieved by looking at global composite seasonal means and monthly time series over 12 regions around the world (Europe, Eastern Russia and Northern Asia, Australia, Mexico, South America, 2 sub-regions for Northern America and South Asia, 3 sub-regions for Africa), considering separately but simultaneously measurements from IASI morning and evening overpasses. The seasonal cycle is inferred for the majority of these regions. The relations between the NH3 atmospheric abundance and emission processes is emphasized at smaller regional scale by extracting at high spatial resolution the global climatology of the month of maxima columns. In some region, the predominance of a single source appears clearly (e.g. agriculture in Europe and North America, fires in central South Africa and South America), while in others a composite of source processes on small scale is demonstrated (e.g. Northern Central Africa and Southwestern Asia).
Chapter 6 presents the achievements of this thesis, as well as ongoing activities and future perspectives.
FRANCAIS:
Le cycle naturel de l'azote est fortement perturbé suite aux émissions atmosphériques de composés azotés réactifs (Nr) résultant de nos besoins accrus en énergie et en nourriture. Les émissions d'ammoniac (NH3) ont doublé au cours du siècle dernier, représentant aujourd'hui plus de la moitié des émissions totales de Nr. De plus, le NH3 étant le principal composé basique de notre atmosphère, il réagit rapidement avec les composés acides pour former des aérosols. C'est dès lors un constituant prépondérant pour l'environnement, le climat et la santé publique. Les problématiques environnementales y étant liées sont décrites au Chapitre 1. En tant que gaz en trace le NH3 se caractérise par une importante variabilité spatiale et temporelle. Bien que des mesures in situ soient possibles, elles sont souvent rares et couvrent le globe de façon hétérogène. Il en résulte un manque de connaissance sur l'évolution temporelle et la variabilité spatiale des émissions, ainsi que de leurs amplitudes, qui représentent les plus grandes incertitudes pour le cycle de l'azote (également décrites au Chapitre 1).
Récemment, les sondeurs spatiaux opérant dans l'infrarouge ont démontré leurs capacités à mesurer le NH3 et par là à compléter le réseau d'observations de surface. Particulièrement, l'Interféromètre Atmosphérique de Sondage Infrarouge (IASI), à bord de la plateforme MetOp, mesure le NH3 à une relativement haute résolution spatiotemporelle. Il couvre le globe deux fois par jour, grâce à son orbite polaire et son balayage autour du nadir, avec un temps de passage à 9h30 et à 21h30 (temps solaire local quand il croise l'équateur). Une nouvelle méthode de restitution des concentrations basée sur le calcul d'un index hyperspectral sans dimension (HRI) est détaillée et comparée aux méthodes précédentes au Chapitre 2. Cette méthode permet d'exploiter de manière plus approfondie le caractère hyperspectral de IASI en se basant sur une bande spectrale plus étendue (800-1200 cm-1) au sein de laquelle le NH3 est optiquement actif. Nous décrivons comment restituer ces concentrations deux fois par jour sans nécessiter de grandes ressources informatiques et avec un meilleur seuil de détection. Plus spécifiquement, la procédure de restitution des concentrations consiste en deux étapes: le HRI est calculé dans un premier temps pour chaque spectre puis est ensuite converti en une colonne totale de NH3 à l'aide de tables de conversions. Ces tables ont été construites sur base de simulations de transfert radiatif effectuées pour différentes conditions atmosphériques. Le processus de restitution des concentrations comprend également le calcul d'une erreur sur la colonne mesurée. Des distributions globales moyennées sur cinq ans (du 1 novembre 2007 au 31 Octobre 2012) sont présentées et analysées séparément pour le passage diurne et nocturne de IASI. L'avantage de ce nouvel algorithme par rapport aux autres méthodes, permettant l'identification de sources plus faibles de NH3 ainsi que du transport depuis les sources terrestres au-dessus des océans, est démontré. Le bénéfice de la haute couverture spatiale et temporelle de IASI est mis en exergue par une description régionale au-dessus de la Chine ainsi que par l'analyse de premières séries temporelles hémisphériques sur quatre ans.
Au Chapitre 3, nous évaluons quatre ans (du 1 janvier 2008 au 31 décembre 2011) de mesures matinales de IASI ainsi que de simulations du modèle LOTOS-EUROS, effectuées au-dessus de l'Europe et de l'ouest de la Russie. Nous décrivons une méthodologie pour prendre en compte, dans la comparaison avec le modèle, la sensibilité variable de l'instrument IASI pour le NH3. Les comparaisons montrent alors une bonne concordance générale entre les mesures et les simulations. Les distributions pointent trois régions sources: la vallée du Pô, le nord-ouest de l'Europe continentale et la vallée de l'Ebre. L'analyse des distributions annuelles montre qu'en moyenne, les colonnes de NH3 mesurées sont plus élevées que celles simulées, à part pour quelques cas spécifiques. Des différences importantes ont été identifiées au-dessus de zones industrielles en Europe de l'est et en Russie, ce qui tend à incriminer une sub-estimation voire une absence de ces sources dans les inventaires d'émissions utilisés en entrée du modèle. Nous avons également montré que la saisonnalité est bien reproduite une fois la sensibilité des mesures satellites prise en compte. La meilleure concordance entre le modèle et IASI est observée pour les Pays-Bas, ce qui est certainement dû au fait que le profil temporel des émissions utilisé pour les simulations LOTOS-EUROS est basé sur des études expérimentales réalisées dans ce pays. L'étude des séries temporelles journalières indique que la dynamique du modèle est raisonnablement en accord avec les mesures mais pointe néanmoins une possible mauvaise représentation du profil temporel ainsi que de l'ampleur des émissions. Finalement, l'étude des importants feux ayant eu cours en Russie à l'été 2010 a montré que les panaches modélisés sont moins étendus que ceux observés, ce qui a été confirmé grâce à une comparaison avec des mesures sols.
Le chapitre 4 est dédié à la confrontation des mesures IASI avec différents jeux de données indépendants acquis depuis le sol et par avion. Les distributions globales annuelles sont concordantes, bien que la couverture spatiale des mesures sols soit limitée. Des mesures effectuées à la surface en Europe, en Chine et en Afrique sont utilisées pour les comparaisons mensuelles. Ces dernières révèlent une bonne concordance générale, bien que les mesures satellites montrent une plus faible amplitude de variations de concentrations. Des corrélations statistiquement significatives ont été calculées pour de nombreux sites, mais les régressions linéaires sont caractérisées par des pentes faibles et des ordonnées à l'origine élevées dans tous les cas. Au minimum, trois raisons contribuent à expliquer cela: (1) le manque de représentativité des mesures ponctuelles pour l'étendue des pixels IASI, (2) l'utilisation d'une seule forme de profil vertical pour la restitution des concentrations, qui ne prend dès lors pas en compte la hauteur de la couche limite, (3) l'impact de la procédure utilisée pour moyenner les observations satellites afin d'obtenir des quantités comparables aux mesures sols mensuelles. La prise en compte de mesures en surface effectuées à plus haute résolution temporelle ainsi que de mesures faites depuis un avion permet d'évaluer les observations IASI individuelles. Les coefficients de corrélation calculés sont bien plus élevés, en particulier pour la comparaison avec les mesures effectuées depuis l'avion NOAA WP-3D pendant la campagne CalNex en 2010. Ces résultats démontrent la nécessité de ce type d'observations, effectuées à différentes altitudes et couvrant une plus grande surface du pixel, pour valider les colonnes IASI-NH3.
Les six ans de données IASI disponibles à la fin de cette thèse sont utilisées pour tracer les premières séries temporelles sub-continentales (Chapitre 5). Plus spécifiquement, nous explorons les mesures IASI durant cette période (du 1 janvier 2008 jusqu'au 31 décembre 2013) pour identifier des structures saisonnières ainsi que la variabilité inter-annuelle à l'échelle sous-continentale. Pour arriver à cela, des moyennes saisonnières composites ont été produites ainsi que des séries temporelles mensuelles au-dessus de 12 régions du globe (Europe, est de la Russie et nord de l'Asie, Australie, Mexique, Amérique du Sud, 2 sous-régions en Amérique du nord et en Asie du sud et 3 sous-régions en Afrique), considérant séparément mais simultanément les mesures matinales et nocturnes de IASI. Le cycle saisonnier est raisonnablement bien décrit pour la plupart des régions. La relation entre la quantité de NH3 atmosphérique et ses sources d'émission est mise en exergue à l'échelle plus régionale par l'extraction à haute résolution spatiale d'une climatologie des mois de colonnes maximales. Dans certaines régions, la prédominance d'un processus source apparait clairement (par exemple l'agriculture en Europe et en Amérique du nord, les feux en Afrique du Sud et en Amérique du Sud), alors que, pour d'autres, la diversité des sources d'émissions est démontrée (par exemple pour le nord de l'Afrique centrale et l'Asie du sud-ouest).
Le Chapitre 6 reprend brièvement les principaux aboutissements de cette thèse et présente les différentes recherches en cours et les perspectives associées.
Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
Yulipriyanto, Hiéronymus. "Emission d'effluents gazeux lors du compostage de substrats organiques en relation avec l'activité microbiologique (nitrification/dénitrification)". Phd thesis, Université Rennes 1, 2001. http://tel.archives-ouvertes.fr/tel-00654701.
Testo completoAlrumayan, F., A. Alghaith, Q. Akkam, A. Marsood e M. AlQhatani. "Development of [NH3] Ammonia target for Cyclone-30 at KFSH&RC". Helmholtz-Zentrum Dresden - rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-165921.
Testo completoLaios, Michail. "Ammonia Metal Halides Thermochemical Heat Storage System Design". Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263607.
Testo completoEn av de mest avgörande frågorna i dag är skyddet av miljön och utfasningen av fossila bränslen som används allmänt över hela världen för mer effektiva och förnybara resurser. Den största delen av den globala energibehovet idag avser uppvärmnings- och kylapplikationer. Ett sätt att minska fossilbaserad termiskenergianvändning är att lagra överskottsvärmeenergi genom termokemiska lagringsmaterial (TCM) och använda den för värme- och kylbehov vid olika tidpunkter och platser. I samband med detta är ett termokemiskt värmelagringssystem numeriskt utformat i detta mastersexamensprojekt, som en del av ett samarbetsprojekt Neutrons for Heat Storage (NHS) finansierat av Nordforsk. Det termokemiska lagringssystemet (TCS) som är konstruerat utnyttjar den reversibla kemiska reaktionen av ammoniak med en metallhalogenid (MeX) för en värmelagringskapacitet på 0.5 kWh, och frigör och lagrar värme respektive under absorption och desorption av ammoniak till och från MeX. Systemet är designat för lågtemperaturuppvärmningstillämpningar runt 40-80 °C. SrCl2 väljs som det mest lämpliga metallhalogeniden för systemet, baserat på studier som utförts av NHS-projektpartnerna. I ammoniak SrCl2-systemet beaktas endast absorption och desorption mellan SrCl2NH3 och SrCl28NH3. De huvudsakliga orsakerna till detta är att absorptionen/desorptionen mellan den sista aminen och SrCl2 kräver ett betydligt högre/lägre reaktionstryck (för en given temperatur), och resulterar i en betydande volymförändring jämfört med resten av aminerna, och är därför praktiskt taget mindre kostnadseffektivt. Detta mastersexamensprojekt inkluderar en detaljerad genomgång av fyra olika TCS-system från litteratur som använder reaktionen mellan ammoniak och metallhalogenider. Dessa väljs här eftersom dessa anses vara de mest relevanta (från litteratur) jämfört med det valda systemet i denna studie. Det första undersökta systemet är ett system byggt av NHS-projektpartnerna vid Danmarks Tekniska Universitet (DTU). Detta har valts på grund av likheterna med det önskade systemet i det aktuella mastersexamensprojektet, vad gäller systemdesign och parametrar. Detta system fungerar i batch-läge, vilket endast tillåter antingen absorption (dvs värmeavgivning) eller desorption (dvs värmelagring) under en specifik cykel. Således kan en uppgraderad design av detta TCS-system vid DTU möjligen vara en lämplig lösning på forskningsmålen för detta mastersexamensprojekt. Dessutom använder detta TCS-system från DTU ganska liknande driftsförhållanden (temperaturer och tryck) i nivå med det aktuella projektets önskade lågtemperaturintervall på 40-80 °C. Det andra systemet från den litteratur som diskuterats använder två reaktorer för kyla och värmeproduktion, vilket innebär att både laddningsoch urladdningsprocesser sker samtidigt. Denna samtidiga operation är främst anledningen till att systemet undersöktes, eftersom detta är en önskad funktion att uppnå i det aktuella projektet. Nästa system från den litteratur som diskuteras häri använder också två reaktorer för absorptions- och desorptionsprocesser, som fungerar reversibelt när varje process är klar, precis som önskat i detta projekt. Dessa två system (dvs det andra och det tredje diskuterade systemen) använder den reversibla fastgasreaktionen för absorption och desorption mellan SrCl2NH3 och SrCl28NH3, dock vid olika tryck- och temperaturförhållanden. Det andra systemet arbetar nämligen under kombinationer av absorption och desorption av 96 °C, 15 bar och 87 °C, 11 bar, medan det tredje systemet arbetar vid 103 °C, 16 bar respektive 59 °C, 3 bar. Det sista systemet som diskuterats från litteraturen arbetar vid samma temperatur som det önskade systemet gör (dvs. 80 ° C) och genom olika lågtrycksexperiment visar att den fasta salt-gasreaktionen är ett bättre val än reaktionen av det fasta saltet med flytande gasreaktion. De viktigaste skillnaderna mellan alla dessa diskuterade system från litteratur i motsats till det önskade TCS-system i detta mastersexamensprojekt, avser systemdriftläge samt deras tryck och X temperaturförhållanden. Den första skillnaden är att endast ett av alla undersökta system pumpar saltet i fast pulverform, till skillnad från de andra som håller saltet stillastående i reaktorerna och endast pumpar ammoniak. Den andra skillnaden gäller driftsförhållandena under absorptions- och desorptionsreaktioner där dessa system arbetar vid mycket olika tryck- och temperaturförhållanden jämfört med det nuvarande systemet. Således, från översynen av alla system, finns det fyra huvudsakliga lärdomar för att förbättra TCS-systemet vid DTU till det önskade nya systemet. Den första är relaterad till reaktanttransportmekanismen som bör användas i detta system. I detta avseende har det beslutats att hålla det fasta saltet (metallhalogenid) stillastående i varje reaktor (men inte pumpa det istället för ammoniak), till skillnad från de flesta system i litteraturen. Enligt dem andra och tredje lektionerna är den fasta gasreaktionen den mest lämpliga lösningen och endast reaktionerna på absorption och desorption mellan SrCl2∙NH3 och SrCl2∙8NH3 bör övervägas enligt erfarenheten från litteraturen (av de skäl som förklarats tidigare). Den sista lärdomen avser systemets lämpliga driftsförhållanden och mer specifikt TCS-systemets temperaturer för att matcha fjärrvärmetemperaturerna. Den temperaturpunkten valts som prioritet, från området 40-80 °C inställt av moderprojektet NHS, sattes till 80 °C. För att bibehålla detta tillstånd var det lämpligaste tryckvillkoret för båda reaktionerna (enligt jämviktstrycket kontra temperaturkurva) valdes att ligga på cirka 8 bar. Samma tryck valdes för båda reaktionerna, eftersom tryckskillnaden mellan dessa reaktorer och lagring av ammoniak (dvs. från 8 till 10 bar) borde vara så liten som möjligt på grund av de höga kostnaderna som kan uppstå vid högre tryckskillnad (dvs. fler kompressorer krävs och värmeväxlare). Inspirerad av denna litteratur föreslogs för det första ett konceptuellt lämpligt TCS-system i detta mastersexamensprojekt, varefter det slutliga systemet implementerades och utvärderades numeriskt för de önskade förhållandena. Den numeriska utformningen och optimeringen av det valda TCS-systemet utfördes här med hjälp av programvaran Aspen Plus (version 9), som innehåller både vätskor och fasta ämnen i en simuleringsmiljö, med konstant fysiska egenskaper. Detta TCS-system är utformat för att lagra och släppa värme vid cirka 80 °C och 8 bar genom absorption och desorption med användning av två identiska reaktorer respektive. Varje reaktor innefattar cirka 1 kg (närmare bestämt 0.985 kg) strontiumkloridsalt reagerande med 1.7 kg ammoniak. Ett verifieringssystem modelleras också i Aspen med hjälp av tillgängliga experimentella data från litteraturen. I detta anpassades den modellerade nya systemdesignen till denna valda andra verifieringssystemlayout från litteratur, som använder samma reaktionspar, men under olika driftsförhållanden. Denna anpassade systemdesign i Aspen användes sedan för att verifiera den valda konfigurationen och tillförlitligheten för det designade systemet för NHS-projektet. Här erhålls ett bra avtal för denna verifieringssystemdesign mellan Aspenmodellresultaten och experimentdata. Här utförs också en känslighetsanalys för det utformade TCSsystemet i det aktuella projektet för att identifiera de optimala driftsförhållandena och beteendet för de valda viktigaste parametrarna i systemet. Det konstruerade systemet ger en energilagringskapacitet på 0.5 kWh för de specifika mängderna (i volymflöde) av ammoniak och monoamin av strontiumklorid, som kommer från analysen, av 1.08696 e-05 kmol/s och 1.5528 e-06 kmol/s respektive. För dessa specifika värden på värmeöverföringsvätskan visade analysen att de volymetriska flödeshastigheterna för värme och kalla yttre källor måste vara 1.56 l/min (vilket minskar när temperaturen på värmeöverföringsvätskan ökar) och 0.42 l/min (som ökar när temperaturen på värmeöverföringsvätskan ökar). Sammanfattningsvis presenterar denna studie ett ammoniak-SrCl2 TCS-bänkskålsystem som möjliggör kontinuerlig värmelagring och frigöring, har en design som är lätt att anpassa och föreslår också optimala driftsförhållanden.
Nightingale, Jonathan Ramsay. "Spectroscopy of NHâ†2 as photofragment from ammonia". Thesis, University of Bristol, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292455.
Testo completoLeick, Barbara Cornelia Elisabeth. "Emission von Ammoniak (NH3) und Lachgas (N2O) von landwirtschaftlich genutzten Böden in Abhängigkeit von produktionstechnischen Maßnahmen". [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10976183.
Testo completoQuaresma, FabrÃzia da Silva. "Lethal concentration (LC50-96h) and sublethal effects of un-ionized ammonia on haematological para parameters of fingerlings tambacu (Colossoma macropomum x Piaractus mesopotamicus)". Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16666.
Testo completoA amÃnia à um composto tÃxico para os organismos aquÃticos e em elevadas concentraÃÃes na Ãgua pode causar diversas alteraÃÃes no animal. Dessa forma, torna-se importante determinar o limite de tolerÃncia dos animais aquÃticos cultivados à essa substÃncia. Sendo assim, o objetivo do trabalho foi determinar a concentraÃÃo letal mÃdia (CL50-96h) da amÃnia nÃo ionizada (NH3) em alevinos de tambacu (Colossoma macropomum x Piaractus mesopotamicus), em teste de toxicidade aguda e avaliar os efeitos de concentraÃÃes subletais atravÃs da anÃlise de parÃmetros hematÃlogicos. No teste de toxicidade aguda, os alevinos foram expostos à amÃnia, nas concentraÃÃes de: 0,09 (controle); 0,54; 1,23; 2,52; 3,44 e 3,66 mg L-1 NH3, que foram obtidas a partir da aplicaÃÃo de NH4Cl. O teste teve duraÃÃo de 96h e as mortalidades foram registradas ao longo desse perÃodo. A CL50 foi determinada pelo mÃtodo estatÃstico Trimmed Spearman Karber. No teste de exposiÃÃo subletal à amÃnia, utilizou-se as concentraÃÃes: 0,04 (controle), 0,19 e 0,35 mg L-1 NH3. Para anÃlise dos parÃmetros hematolÃgicos, foram realizadas coletas de sangue antes da adiÃÃo de NH4Cl (tempo zero) e apÃs 96h de exposiÃÃo. Os parÃmetros hematolÃgicos analisados foram: hematÃcrito (Ht), taxa de hemoglobina (Hb), nÃmero de eritrÃcitos (RBC), volume corpuscular mÃdio (VCM), hemoglobina corpuscular mÃdia (HCM) e concentraÃÃo de hemoglobina corpuscular mÃdia (CHCM). Os dados dos parÃmetros hematolÃgicos foram submetidos à anÃlise de variÃncia (ANOVA) e quando houve diferenÃa significativa entre os tratamentos, as mÃdias foram comparadas duas a duas atravÃs do teste de Tukey (α=0,05). A CL50-96h da amÃnia nÃo ionizada (NH3) para alevinos do hÃbrido tambacu foi 1,63 mg L-1. ApÃs exposiÃÃo de 96h a 0,35 mg L-1 NH3, os peixes apresentaram reduÃÃes significativas no Ht e VCM e aumento significativo na CHCM. Jà Hb, RBC e HCM nÃo diferiram significativamente entre os tratamentos e o tempo 0. A exposiÃÃo de alevinos de tambacu por curto perÃodo de tempo a 0,19 mg L-1 de amÃnia nÃo ionizada (NH3) nÃo causa alteraÃÃes significativas nos parÃmetros hematolÃgicos desses peixes.
Ammonia is a toxic compound to aquatic organisms and at high concentrations in the water can cause various changes in the animal. Therefore, it becomes important to determine the tolerance of farmed aquatic animals for that substance. Thus, the aim of this study was to determine the median lethal concentration (LC50-96h) of un-ionized ammonia (NH3) in fingerlings tambacu (Colossoma macropomum x Piaractus mesopotamicus) in acute toxicity test and evaluate the effects of concentrations sublethal through the analysis of hematological parameters. In the acute toxicity test, the fingerl ings were exposed to ammonia at concentrations of: 0,09 (control); 0,54; 1,23; 2,52; 3 ,44 and 3,66 mg L-1NH3, which were obtained from the application of NH4Cl. The test lasted 96 hours and mortalities were recorded over that period. The LC50 was determin ed by statistical method Trimmed Spearman Karber . In sublethal exposure to ammonia test concentrations used were : 0,04 (control), 0,19 and 0,35mg L-1NH3.For analysis of hematological parameters, blood samples were collected before the addition of NH4Cl(timezero) and after 96 hours of exposure.The hematological parameters analyzed were: hematocrit ( Ht), hemoglobin(Hb), red blood cell count(RBC) mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration(MCHC). Data hematological parameters were subjected to analysis of variance (ANOVA) and when there was a significant difference between treatments , the averages were compared in pairs through the Tukey's HSD test (α=0,05).LC50-96h of theun - ionized ammonia (NH3) to fingerlings the hybrid tambacu was 1,63m g L-1. After 96h exposure to 0,35 mg L-1NH3, fish showed significant reductions in hematocrit and the MCV and significant increase in MCHC. Already Hb,RBC and MCH did not differ significantly between treatments and time 0. The exposure to fingerlins tambacu for short period to 0,19 mg L -1 of un-ionized ammonia (NH3) does not cause significant changes in hematological parameters of these fish.
Amaris, Castilla Carlos Fidel. "Intensification of NH3 bubble absorption process using advanced surfaces and carbon nanotubes for NH3/LINO3 absorption chillers". Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/128504.
Testo completoThis thesis deals with an experimental study on intensification of the ammonia absorption process in the NH3/LiNO3 mixture in vertical bubble mode absorbers using advanced surfaces and nanoparticles of carbon nanotubes (CNTs). Operating conditions selected for the absorber test were obtained from a thermodynamic analysis of a single effect absorption cycle with NH3/LiNO3 driven by low temperature heat sources and head released by air. The experiments were conducted in an experimental test facility designed for evaluating the absorber performance at the desired operating conditions. Intensification of the ammonia absorption process was studied using two types of heat exchangers working as bubble absorbers; a plate heat exchanger and a tubular heat exchanger. Experimental results showed that the advanced surfaces and CNTs used significantly improve the ammonia absorption process in the tubular bubble absorber analyzed in comparison with results in the smooth tube absorber with the base fluid. The maximum improvements achieved were higher than 50 %.
Valdez, Lancinha Pereira Mafalda. "Étude des processus de formation et élimination du N2O lors de la Réduction Catalytique de NOx par le NH3 (NH3-SCR)". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2016. http://www.theses.fr/2016ENCM0015.
Testo completoThe thesis project focused on the study of the formation and elimination of N2O by copper-zeolite or iron-zeolite catalysts, used for selective catalytic reduction of NOx with ammonia (NH3-SCR). In the NOx reduction process the main N2O formation routes are the decomposition of the ammonium nitrate (NH4NO3) and the NH3 oxidation. Still, a literature review showed a more important contribution from the decomposition of ammonium nitrate. Therefore, the study was then concentrated on the decomposition of the ammonium nitrate in two axes: the decomposition of commercial NH4NO3 and the in situ formation followed by decomposition of ammonium nitrate.Besides, the catalysts used for this study, have been thoroughly characterized by different physicochemical techniques in order to, particularly, assess the concentration and deposition form of metals, the acidity and the size of the crystals.After performing the decomposition of commercial NH4NO3 without catalyst, the study has focused on the effect of interaction with a catalyst. The effect of the carrier gas, the hydrodynamic conditions and concentration of NH4NO3 were also studied.Under static conditions, i.e. without liquid NH4NO3 entrainment, the decomposition of the commercial ammonium nitrate mostly leads to N2O. In contrast, the reaction pathway under dynamic conditions depends on the deposition method of ammonium nitrate onto the catalyst. The solid aggregates in the outer surface of the catalyst decompose directly to N2O, especially when the liquid ammonium nitrate cannot be entrained by the carrier gas. The absence of a catalyst promotes the decomposition into nitrogen, formed by the interaction between the NH3 and HNO3 released upon the dissociation of NH4NO3. On the other hand, in the presence of a catalyst NH3 tends to adsorb and to be oxidized at higher temperatures. The carrier gas composition did not have a significant effect in the decomposition of NH4NO3.The decomposition of ammonium nitrate formed in situ was performed in order to get closer from what happens under SCR conditions, where the ammonium nitrate is formed by the interaction between NH3 and NO2. The experimental method was designed to maximize the formation of ammonium nitrate according to the two extreme conditions that may be found in a SCR system: firstly catalyst saturation by NH3 and then by NO2 (“NH3 experiment”) and then the reverse, saturation by NO2 and then by NH3 (“NO2 experiment”). In this study several catalysts were prepared in order to isolate certain characteristics and assess their impact. The effects of the copper loading, the type of metal (Cu and Fe), the structure of the zeolite (CHA or FER), the method of preparation, the calcination atmosphere and the carrier gas during decomposition were studied. These effects were correlated to the results of the physico-chemical characterization of the catalysts with the purpose of find the cause of the faced differences.The formation of N2O during the “NH3 experiment” is always greater than that obtained on the “NO2 experiment”, and strongly depends on the concentration of the Brönsted acid sites, regardless the zeolite structure. However, on the “NO2 experiment”, it is rather the metal species and its location that influence the decomposition of ammonium nitrate. The size of the crystals also has an influence. The preparation method and the calcination atmosphere do not have a significant effect. The carrier gas impacts on the high temperature emission: the formation of N2O is greater in the presence of oxygen
Högström, Åsa. "Sulfur poisoning and regeneration of copper zeolites for NH3-SCR : Effect of SO2/SO3 ratio". Thesis, Luleå tekniska universitet, Kemiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72218.
Testo completoOnye, Jermain Eze. "Atmospheric Corrosion of Zn by NaCl, SO2, NH3, O3, and UV Light". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408822401.
Testo completoLeMonte, Joshua James. "Environmental Implications of Polymer Coated Urea". BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/3010.
Testo completoUzun, Alper. "Quantum Chemical Simulation Of No Reduction By Ammonia (scr Reaction) On V2o5 Catalyst Surface". Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1090430/index.pdf.
Testo completonsted acidic V-OH site as NH4 + species by a nonactivated process with a relative energy of -23.6kcal/mol. Vibration frequencies were calculated as 1421, 1650, 2857 and 2900cm-1 for the optimized geometry, in agreement with the experimental literature. Transition state with a relative energy of -17.1kcal/mol was also obtained. At the end of the Lewis acidic ammonia interaction calculations, it was observed that ammonia is hardly adsorbed on the surface. Therefore, it is concluded that the SCR reaction is initiated more favorably by the Brø
nsted acidic ammonia adsorption. As the second step of the SCR reaction, NO interaction with the preadsorbed NH4 + species was investigated. Accordingly, NO interaction results in the formation of gas phase NH2NO molecule with a relative energy difference of 6.4kcal/mol. For the rest of the reaction sequence, gas phase decomposition of NH2NO was considered. Firstly, one of the hydrogen atoms of NH2NO migrates to oxygen. It then isomerizes in the second step. After that, the reaction proceeds with the isomerization of the other hydrogen. Finally, a second hydrogen atom migration to the oxygen leads to the formation of N2 and H2O. Total relative energy for this reaction series was obtained as -60.12kcal/mol, in agreement with the literature.
Wright, K. M. "The influence of ammonia on photosynthetic and dark CO2̲ fixation in higher plants". Thesis, University of Newcastle Upon Tyne, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379318.
Testo completoRODRIGUEZ, RAFAEL MARTINEZ. "EXPERIMENTAL AND THEORETICAL ANALYSIS OF (NH3)NNHM(+)(-) ION CLUSTERS DESORBED FROM SOLID AMMONIA BOMBARDED BY 65 MEV ION PROJECTILES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11495@1.
Testo completoUm espectrômetro de massa tipo tempo-de-vôo, montado no Laboratório Nacional de Luz Síncrotron (Campinas - SP), foi utilizado para analisar os íons dessorvidos de uma amostra de amônia condensada (temperaturas de análise: 25 a 150 K) ao ser impactada por fragmentos de fissão do 252Cf. O espectrômetro permite identificar e determinar as abundâncias das espécies iônicas dessorvidas. Quanto à parte teórica, foram feitos cálculos para determinar as estruturas mais estáveis dos agregados de NH3 e para determinar suas dinâmicas de emissão de íons secundários observados na parte experimental. A amônia foi escolhida por sua semelhança com a água, uma molécula muito bem estudada. Outra razão é o atual interesse em determinar a formação de compostos orgânicos nas superfícies de corpos interestelares, uma vez que está comprovada a presença da amônia naquelas superfícies. Nos espectros obtidos observa-se a formação de agregados de amônia que podem ser representados por (NH3)nNHm ± com n = 0-30 e m = 0-5, para íons positivos, e com n = 0- 3 para íons negativos. Uma forma de evidenciar a possibilidade de formação de novos compostos foi realizar experiências com a mistura NH3-CO, com a mesma montagem experimental utilizada para a amônia. Observa-se no espectro obtido (antes da sublimação do CO a 30 K) linhas de massa resultantes de reações primárias que correspondem a íons moleculares híbridos com estrutura CnOmHl+.Os cálculos teóricos referentes às estruturas dos agregados foram realizados través do programa Jaguar 5.5 e Jaguar 6.0. O objetivo é determinar as estruturas mais estáveis dos agregados iônicos da amônia através da teoria DFT (Teoria do Funcional de Densidade) por meio da minimização da energia. Encontrou-se uma relação direta entre as estabilidades determinadas e as abundâncias relativas no espectro de massa. Finalmente foram realizados cálculos com o modelo teórico de dessorção iônica induzida por elétrons. Os resultados de distribuição de velocidades e energias foram comparados com os dados experimentais dos agregados da amônia (n = 0, 4), apresentando uma concordância razoável em valor absoluto, mas moderada em forma.
A time-of-flight mass spectrometer, mounted at the Laboratório National de Luz Síncrotron (Campinas - SP), was used to analyze desorbed ions of a condensed ammonia sample (analyzing temperatures: 25 - 150 K) being impacted by 252Cf fission fragments . The spectrometer allows identifying and determining the relative yields of ionic desorbed species. Besides, it had been made theoretical calculations to determine the most stable cluster structures as well as to determine the emission dynamics of NH3 clusters observed in the experimental part. The ammonia was chosen because of its similarity with the water molecule (very well studied). Another reason is the current interest in determining the organic compounds formation in the interstellar surfaces, now that it is proven the presence of ammonia in those surfaces. The measured spectra show the formation of ammonia clusters that can be represented by (NH3)nNHm ± with n = 0 - 30 and m = 0 - 5 for positive ions, and n = 0 - 3 for negative ones. One way to evidence the formation possibility of new compound is to perform experiments with CO-NH3 mixture samples, using the same experimental set up used for the ammonia. In the spectrum measured before CO sublimation (30 K), mass lines, product of primary reactions, corresponding to hybrid molecular ions having the CnOmHl + structure were observed. Theoretical calculations referring to cluster structures had been carried out using the programs Jaguar 5,5 and Jaguar 6.0. The objective is to determine the most stable structures of the ammonia clusters through the Density Functional Theory (DFT) by means of energy minimizations. A direct relation between the computed stabilities and the relative abundances in the mass spectra was found. Finally calculations with the Secondary Electron Induced Desorption (SEID) model had been carried out. Results of velocity and energy distributions had been compared with the experimental data of ammonia clusters (n = 0, 4), presenting a good agreement in absolute values but moderate agreement in shape.
Alves, Ana Carolina. "Perdas de amônia por volatilização e emissão foliar em pastagem adubada com fontes de nitrogênio". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/74/74131/tde-08092009-113400/.
Testo completoIn search of alternatives to measure ammonia (NH3) foliar emission and minimize N-NH3 losses in pasture three research works were accomplished. The two first works aimed at checking whether or not the foam absorber, which was already used to quantify N-NH3 volatilization, is also efficient to measure foliar emission without interfering in nitrogen loss process. The third one was performed in Panicum maximum Jacq. cv. Colonião pasture during three different seasons and evaluated the use of irrigation levels after urea fertilization on N-NH3 losses through volatilization and foliar emission. The ammonia foam absorber does not alter N-NH3 loss process and when place at height of 1 cm from the upper leaves it is effective in capturing N-NH3 lost through foliar emission when fertilization is done superficially with ammonium nitrate and urea. Water application immediately after fertilization is efficient to reduce N-NH3 losses through volatilization. During summer the use of 3.2 mm water was enough to decrease N-NH3 loss to less than 3.1% of applied N, while the lack of irrigation caused 30.5% losses. Volatilization rate is influenced by the quantity of water available in the soil, being low when urea is applied to dry soil or when the soil dries fast even if the environment temperature is high. N-NH3 foliar emission was not influenced by water application after urea fertilization.
Mohammed, Priscilla Naseem. "Laboratory Measurements of the Millimeter Wavelength Opacity of Phosphine (PH3) and Ammonia (NH3) Under Simulated Conditions for the Cassini-Saturn Encounter". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6927.
Testo completoCardona, Claudia. "Uranium Sequestration by pH Manipulation using NH3 Injection in the Vadose Zone of Hanford Site 200 Area". FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3352.
Testo completoSoyer, Sezen. "Quantum Chemical Simulation Of Nitric Oxide Reduction By Ammonia (scr Reaction) On V2o5 / Tio2 Catalyst Surface". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606632/index.pdf.
Testo completonsted acidic V-OH site as NH4+ species by a nonactivated process takes place. The second part includes the interaction of NO with pre-adsorbed NH4 + species to eventually form nitrosamide (NH2NO). The rate limiting step for this part as well as for the total SCR reaction is identified as NH3NHO formation reaction. The last part consists of the decomposition of NH2NO on the cluster which takes advantage of a hydrogen transfer mechanism between the active V=O and V-OH groups. Water and ammonia adsorption and dissociation are investigated on (101) and (001) anatase surfaces both represented by totally fixed and partially relaxed Ti2O9H10 clusters. Adsorption of H2O and NH3 by H-bonding on previously H2O and NH3 dissociated systems are also considered. By use of a (001) relaxed Ti2O9H10 cluster, the role of anatase support on SCR reaction is investigated. Since NH2NO formation on Ti2O9H10 cluster requires lower activation barriers than on V2O5 surface, it is proposed that the role of titanium dioxide on SCR reaction could be forming NH2NO. The role of vanadium oxide is crucial in terms of dissociating this product into H2O and N2. Finally, NH3 adsorption is studied on a V2TiO14H14 cluster which represents a model for vanadia/titania surface.
Marcaggi, Païkan. "Capture de NH4+ dans les cellules gliales de rétine d'abeille par un transporteur membranaire spécifique". Bordeaux 2, 1999. http://www.theses.fr/1999BOR28698.
Testo completoAmblard, Matthieu. "An investigation of the selective oxidation of NHâ†3 to Nâ†2 by Alâ†2Oâ†3-supported metal oxide catalysts using oxidising conditions". Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299554.
Testo completoAl, Ibrahim Ali. "Contribution à l'amélioration de la fertilité des sols : dynamique interfoliaire de Nh4+ et K+ dans une vermiculite". Toulouse, INPT, 1987. http://www.theses.fr/1987INPT004A.
Testo completoDeka, Dhruba Jyoti. "Development of Cathode Catalysts for the Production of Synthesis Gas and Ammonia in Solid Oxide Electrolysis Cells". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1588693027481087.
Testo completoHermandez, Peral Ivan. "Evaluation of the ambient air quality analysis of HCL, H2S and NH3 from enhanced evaporation spray system ponds on the Highveld of South Africa". Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-05262008-090359.
Testo completoSitathani, Krit. "A window into selective catalytic reduction : a RAIRS study of NO and NH3 on Cu{311}". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/264375.
Testo completoGupta, Saurabh. "Selective Catalytic Reduction (SCR) of nitric oxide with ammonia using Cu-ZSM-5 and Va-based honeycomb monolith catalysts effect of H2 pretreatment, NH3-to-NO ratio, O2, and space velocity /". Texas A&M University, 2003. http://hdl.handle.net/1969/526.
Testo completoAttmane-Elakeb, Amel. "Transporteurs de l'ion ammonium NH4+ de la branche large ascendante médullaire du rein : localisation apicale de l'an-". Paris 6, 1997. http://www.theses.fr/1997PA066761.
Testo completoWilson, Glen H. "The regulation of intracellular pH and ammonium in intact rice (Oryza sativa) and Maize (Zea mays) roots : an investigation of the mechanism(s) of NHâ†3 toxicity". Thesis, University of Greenwich, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264710.
Testo completoSantos, Wadson de Menezes. "Desempenho agronômico e volatilização da amônia de fertilizantes pastilhados e convencionais na cultura de milho". Pós-Graduação em Agricultura e Biodiversidade, 2017. http://ri.ufs.br/jspui/handle/riufs/7320.
Testo completoNitrogen is the most required mineral nutrient for almost all agricultural crops and the one that promotes maize yields mostly. Pastillation is a technology that allows blending urea with other mineral elements like sulfur and zinc homogeneously, aims at subsiding N losses, therefore enhancing the agronomic efficiency of the fertilizers. The aim of the first paper was to establish the recommendation of N rates and to evaluate the agronomic performance of pastille urea and its blend with sulfur and zinc, as well as commercial N sources sidedress applied to maize under the conditions of the Médio Sertão and Southern Sergipe. The experiments were carried out during the 2014 and 2015 seasons in both sites. The experimental design was Complete Blocks with 3 replications in split-plot arrangement with an additional Control treatment (TEST). In the plot 3 rates of N applications were tested: 75, 150 and 300 kg ha-1, while in the subplots the following products were evaluated: Pastille urea (UP), Pastille urea with elemental S (UP+S), Pastille urea with ammonium sulfate (UP+SA), Pastille urea with ammonium sulfate and elemental S (UP+SA+S), Pastille urea with ammonium sulfate and zinc sulfate (UP+SA+Zn), Prilled urea (UR) and Ammonium sulfate (SA). Leaf N and S contents as well as maize yield were evaluated to assess the agronomic performance of the products and to calculate the appropriate N recommendation. Economic assessments of the price for the commercial products and the corn grains allowed estimating the rate of maximum economic efficiency (DMEE). The greater the rate of N applied the higher leaf N content and grain yields of maize. Leaf S contents increased with increasing doses of S applied with the tested fertilizers. Yields with Ammonium sulfate were higher than UR, UP and UP+S in both seasons in Umbaúba (Acrisol) (Southern Sergipe). The DMEE for UR was 128 and 119 kg N ha-1 for Nossa Senhora das Dores (Acrisol) and Umbaúba, respectively. The recommended dose of SA was 119 kg ha-1, since it provided the greater incomes for both sites. In the second paper, the aim was to evaluate the agronomic performance and the losses of N through ammonia volatilization of N fertilizers sidedress applied to maize. Ammonia volatilization, leaf N content and maize yield were evaluated in all products tested in the first paper when applied at a rate of 150 kg ha-1 of N and in the TEST treatment. Three replications were used. All fertilized treatments showed higher leaf N contents and grain yields than TEST. The treatment SA showed yields higher than UP+SA+S. Of all N-NH3 lost by volatilization, 92.5% took place in the first 5 days after application. The UP+SA treatment reduced ammonia volatilization and did not differ statistically from SA and TEST. Leaf N content correlates positively and N volatilization negatively with grain yield.
O nitrogênio é o elemento mais requerido pela maioria das culturas e o que proporciona os maiores incrementos no rendimento do milho. O pastilhamento da ureia é uma tecnologia que permite a adição de outros elementos, como enxofre e zinco, e visa diminuir as perdas de N, e consequentemente melhorar a eficiência agronômica dos fertilizantes. No primeiro artigo, o objetivo foi a recomendação de doses de N e avaliação da eficiência agronômica da ureia pastilhada, e de suas complexações com enxofre e zinco, e fontes convencionais de N aplicados em cobertura na cultura do milho nas condições do Médio Sertão e Sul sergipanos. O delineamento experimental foi em blocos ao acaso, com 3 repetições, em esquema de parcelas subdivididas com tratamento adicional. As parcelas foram compostas pelas doses: 75, 150 e 300 kg ha-1 de N, e as subparcelas pelos fertilizantes: ureia pastilhada pura (UP), ureia pastilhada com S elementar (UP+S), ureia pastilhada com sulfato de amônio (UP+SA), ureia pastilhada com sulfato de amônio e S elementar (UP+SA+S), ureia pastilhada com sulfato de amônio e sulfato de zinco (UP+SA+Zn), ureia perolada (UR), sulfato de amônio cristal (SA), e o tratamento adicional testemunha (TEST). Foram avaliados o teor de N e S foliar, produtividade de grãos, e recomendadas doses de máxima eficiência econômica (DMEE). A adubação nitrogenada proporcionou maiores teores de N foliares, e produtividade de grãos, e estas variáveis aumentaram com o acréscimo das doses de N. Os teores de S foliares aumentaram com o incremento das doses de S. O SA proporcionou maior produtividade que a UR, UP e UP+S na média das safras no Argissolo Acinzentado. As DMEE para a UR foram de 128 kg ha-1 de N no Argissolo Vermelho-Amarelo, e 190 kg ha-1 de N no Argissolo Acinzentado. A dose indicada de SA foi de 119 kg ha-1 de N para ambos os solos, e este tratamento proporcionou as maiores rendas. No segundo artigo, o objetivo foi a avaliação da eficiência agronômica e as perdas por volatilização da amônia pela aplicação em cobertura no milho de fertilizantes nitrogenados convencionais e pastilhados, e em suas complexações com enxofre e zinco. Foram avaliados a volatilização da amônia, o teor de N foliar, a produtividade de grãos, e a relação entre estas variáveis. Os tratamentos avaliados foram UP; UP+S; UP+SA; UP+SA+S; UP+SA+Zn; UR e SA, todos na dose de 150 kg ha-1 de N, além da testemunha não adubada (TEST), com 3 repetições. Os tratamentos fertilizados apresentaram os maiores teores de N foliares e produtividade de grãos. O SA apresentou produtividade superior ao tratamento UP+SA+S. Do total de N-NH3 perdido por volatilização, 92,5% ocorreram até o quinto dia após a fertilização. A UP+SA reduziu a volatilização da amônia, não diferindo estatisticamente do SA e TEST. O teor foliar de N correlacionou-se positivamente, enquanto a taxa de volatilização, negativamente, com a produtividade de grãos.
São Cristóvão, SE
Rönnby, Karl. "Quantum Chemical Feasibility Study of Methylamines as Nitrogen Precursors in Chemical Vapor Deposition". Thesis, Linköpings universitet, Kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132812.
Testo completoMiranda, Jose Carlos Vieira de. "Adsor??o dos gases NH3, NO e H2S em fosfato de vanadila, hidrogeno fosfato de vanadila e fosfatos de vanadila dopados por Al, Co, Mn e Cr". Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17770.
Testo completoIn this work were synthesized the materials called vanadyl phosphate, hydrogen vanadyl phosphate and vanadyl phosphate doped by transition metals with the aim in adsorption the following compounds: ammonia, hydrogen sulfide and nitrogen oxide. To characterize the starting compounds was used DRX, FTIR, FRX and TG analysis. After the characterization of substrates, proceeded de adsorption of NH3 and H2S gases in reactor, passing the gases with continuous flow for 30 min and room temperature. Gravimetric data indicate that the matrices of higher performance in adsorption of ammonia was those doped by aluminum and manganese, obtaining results of 216,77 mgNH3/g and 200,40 mgNH3/g of matrix, respectively. The matrice of higher performance in adsorption of hydrogen sulfide was that doped by manganese, obtaining results of 86,94 mgH2S/g of matrix. The synthesis of substrates VOPO4.2H2O and MnVOPO4.2H2O with nitrogen oxide was made in solution, aiming the final products VOPO4.G.nH2O and MnVOPO4.G.nH2O (G = NO and n = number of water molecules). The thermo analytical behavior and the infrared spectroscopy are indicative of formation of VOPO4.2,5NO.3H2O compound. Results of scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS) of materials vanadyl phosphate and vanadyl phosphate modified after reaction in solid state or in solution with the gases show morphology changes in substrates, beyond the formation of orthorhombic sulfur crystals over their respective hosts when these adsorb hydrogen sulfide
Neste trabalho foram sintetizados os materiais denominados fosfato de vanadila, hidrogeno fosfato de vanadila e fosfatos de vanadila dopados por metais de transi??o com fins na adsor??o de am?nia, sulfeto de hidrog?nio e ?xido de nitrog?nio. Para a caracteriza??o dos compostos de partida, recorre-se ?s t?cnicas de DRX, FTIR, FRX e TG. Ap?s a caracteriza??o dos substratos, procedeu-se a adsor??o dos gases NH3 e H2S em reator, passando os gases a vaz?o cont?nua durante 30 min e temperatura ambiente. Dados gravim?tricos indicam que as matrizes de maior desempenho na adsor??o de am?nia foram ?quelas dopadas por alum?nio e mangan?s, obtendo resultado de 216,77 mgNH3/g e 200,40 mgNH3/g de matriz, respectivamente. A matriz de maior desempenho para a adsor??o de sulfeto de hidrog?nio foi ?quela dopada por mangan?s, obtendo resultado de 86,94 mgH2S/g de matriz. As s?nteses dos substratos VOPO4.2H2O e MnVOPO4.2H2O com o g?s ?xido de nitrog?nio foram realizadas em solu??o, objetivando-se os produtos finais VOPO4.G.nH2O e MnVOPO4.G.nH2O (G = NO e n = n?mero de mol?culas de ?gua). O comportamento termoanal?tico e a espectroscopia na regi?o do infravermelho s?o indicativos da forma??o do composto VOPO4.2,5NO.3H2O. Resultados de microscopia eletr?nica de varredura (MEV) e espectroscopia de energia dispersiva (EDS) dos materiais fosfatos de vanadila e fosfatos de vanadila dopados ap?s rea??o no estado s?lido ou em solu??o com os gases indicam mudan?a na morfologia dos substratos, al?m da forma??o de cristais de enxofre ortorr?mbico sobre seus respectivos hospedeiros quando estes adsorvem sulfeto de hidrog?nio
Rogler, Daniela. "Entwicklung einer lichtbogengestützten PECVD-Technologie für die Synthese siliziumbasierter Schichtsysteme unter Atmosphärendruck – Untersuchung des diffusionslimitierten Wachstumsregimes". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-97547.
Testo completoRoupec, Ladislav. "Studie rekonstrukce kořenové čistírny pro obec Dražovice". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265382.
Testo completoCheng, Nicole Colombari. "Eficiência de uso da 15N-ureia tratada com ácido bórico e sulfato de cobre pelo milho". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-29062018-173123/.
Testo completoN is a nutrient used in large quantities in agricultural production systems and it is the most limiting element for production of grasses. Urea is the most widely used nitrogen fertilizer (N fertilizer) in the world and the main focus of the worldwide industry of fertilizers technologically improved, being highly susceptible to losses by volatilization of ammonia (NH3) when applied on soil surface. In order to minimize environmental impact and increase N efficiency, the use of urease inhibitors is one of the most promising and least expensive technologies. In addition, inorganic urease composed for essential elements for plants, such as boric acid (H3BO3) and copper sulfate (CuSO4), can nutritionally supplement agricultural production systems. In this context, two experiments were carried out under controlled conditions (laboratory and greenhouse) with the following objectives: i) laboratory: to quantify NH3 volatilization losses from the surface application of urea treated with different rates of H3BO3 and CuSO4, using closed chamber; (ii) greenhouse: to evaluate the N and B use efficiency from surface application of 15N urea treated with H3BO3 and CuSO4 in two vegetative stages of maize. In the laboratory experiment, there was no interaction between B and Cu rates or any Cu effect on NH3 losses by volatilization. The increase of H3BO3 in the treatment of urea delayed the daily losses of NH3 and reduced (P<0.001) the cumulative volatilization losses of NH3. The rates of B showed a quadratic adjustment and, based on the regression analysis, the estimated rate of maximum efficiency was 0.88% B. Under greenhouse conditions, urease inhibitors delayed and decresed the losses of NH3 by volatilization. Over 15 days after fertilization, treatment with H3BO3 promoted reductions in NH3 volatilization ranging from 6 to 17% compared to untreated urea, and occur differentiation between B rates. The treatments with higher rates of B did not differ from the treatment with N-(n-butyl) thiophosphoric triamide (NBPT) in maize biomass production. The plant height, stem diameter and leaf area index did not show differences between N fertilizers. The morphology of the maize root system was affected by the use of urease inhibitors only in stage V8. The increase of H3BO3 in the urea coating increased on average 10% the efficiency of use of N fertilizer (NUE-F) in relation to untreated urea. In VT growth stage, there was no difference for NUE-F between treatments NBPT and higher rate of H3BO3 (0.88% B). Treatment of U with H3BO3 increased proportionally the accumulation of B in the plant. The addition of CuSO4 did not affect volatilization of NH3 and NUE-F. Urea coating with H3BO3 was an efficient strategy to reduce N losses, to increase the NUE-F and to supply B for plants.
Strandqvist, Carl. "The Functionalization of Epitaxial Graphene on SiC with Nanoparticles towards Biosensing Capabilities". Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120502.
Testo completoCrossley, Samuel. "Electrocaloric materials and devices". Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/245063.
Testo completoLindblad, Andreas. "A Treatise on the Geometric and Electronic Structure of Clusters : Investigated by Synchrotron Radiation Based Electron Spectroscopies". Doctoral thesis, Uppsala University, Department of Physics and Materials Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8463.
Testo completoClusters are finite ensembles of atoms or molecules with sizes in the nanometer regime (i.e. nanoparticles). This thesis present results on the geometric and electronic structure of homogeneous and heterogeneous combinations of atoms and molecules. The systems have been studied with synchrotron radiation and valence, core and Auger electron spectroscopic techniques.
The first theme of the thesis is that of mixed clusters. It is shown that by varying the cluster production technique both structures that are close to that predicted by equilibrium considerations can be attained as well as far from equilibrium structures.
Electronic processes following ionization constitute the second theme. The post-collision interaction phenomenon, energy exchange between the photo- and the Auger electrons, is shown to be different in clusters of argon, krypton and xenon. A model is proposed that takes polarization screening in the final state into account. This result is of general character and should be applicable to the analysis of core level photoelectron and Auger electron spectra of insulating and semi-conducting bulk materials as well.
Interatomic Coloumbic Decay is a process that can occur in the condensed phases of weakly bonded systems. Results on the time-scale of the process in Ne clusters and mixed Ar/Ne clusters are herein discussed, as well observations of resonant contributions to the process. In analogy to Auger vis-à-vis Resonant Auger it is found that to the ICD process there is a corresponding Resonant ICD process possible. This has later been observed in other systems and by theoretical calculations as well in subsequent works by other groups.
Delocalization of dicationic valence final states in the hydrogen bonded ammonia clusters and aqueous ammonia has also been investigated by Auger electron spectroscopy. With those results it was possible to assign a previously observed feature in the Auger electron spectrum of solid ammonia.
RIGONI, FEDERICA. "EXPLORING DETECTION LIMITS AND RESPONSE TIME SCALES OF CHEMIRESISTOR GAS SENSORS BASED ON CARBON NANOTUBE AND HYBRID LAYERS". Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/262413.
Testo completoPokapanich, Wandared. "Solvent–Solute Interaction : Studied by Synchrotron Radiation Based Photo and Auger Electron Spectroscopies". Doctoral thesis, Uppsala universitet, Yt- och gränsskiktsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-138749.
Testo completoFelaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 726
Chang, Jin Chuang, e 張金泉. "Vibrational Spectroscopy of Ammoniated Ammonium Ions NH4+(NH3)n (n=1~6) and Clusters of Water Molecular (H2O)m (m=6,8,10) Studieds with Ab Initio and Density Functional Theory Method". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/72075696633414535832.
Testo completo淡江大學
化學學系
86
In this dissertation, the vibrational spectroscopy of ammoniated ammonium ions NH4+(NH3)n (n=1~6) and clusters of water molecular (H2O)m (m=6,8,10) were studied by theoretical calculations : Ab Initio (MP2) and DFT (B3LYP).In ammoniated ammonium ions NH4+( NH3)n (n=0~6) parts. For n=0 and 1, The geometries of the clusters are optimized at MP2, CCD, QCISD and B3LYP levels with several basis sets, and the bonding energies are compared to experimental results to find the cheap and reliable methods for the calculations of larger clusters. For n=2~6, the geometry optimizations and vibrational configurations are performed at the MP2 and B3LYP levels with 6-31+G* basis set. The bonding energies are corrected by the BSSE (basis set superposition errors) and ZPVE (zero-point vibrational energies). In addition, the barriers of proton transfer between two heavy atoms and the internal rotation of NH3 molecule along the N-H axis in NH4+ in NH4+(NH3)n were estimated at several levels.In water molecular (H2O)m (m=6,8,10) parts. The clusters which possessed 2- and 3-coordinated H2O were chosen to investigate the difference of the free-OH stretching frequencies of 2- and 3 - coordinated H2 O. The geometries were optimized at B3LYP/6-31+G* level. The calculated frequencies are scaled by 0.973. The effects of the directionality of hydrogen bonds and the types of the neighbour waters will affect the amplitude of the frequency red-shia of free-OH stretching in water clusters.
Leick, Barbara Cornelia Elisabeth [Verfasser]. "Emission von Ammoniak (NH3) und Lachgas (N2O) von landwirtschaftlich genutzten Böden in Abhängigkeit von produktionstechnischen Maßnahmen / vorgelegt von Barbara Cornelia Elisabeth Leick". 2004. http://d-nb.info/970077084/34.
Testo completoWang, Chia-Ching, e 王嘉慶. "DFT Study of NHx (x = 0–3) and N2 Adsorption, and Ammonia Oxidation on RuO2(110) and IrO2(110) Surfaces". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/16425141107067882378.
Testo completo國立臺灣科技大學
化學工程系
98
In this thesis, the density functional theory (DFT) calculations were applied to investigate the adsorptions of NHx (x = 0–3) species and N2, and the ammonia oxidation on the RuO2(110) and IrO2(110) surfaces. In the adsorption part, the analyses of density of states (DOS), electron density difference (EDD) and charge difference (?惶) provide the detailed adsorbate–surface interactions. The results demonstrate that each adsorbate has very similar interactions with both the RuO2(110) and IrO2(110) surfaces in this work. The major difference in adsorptions between these two surfaces is that the vacant state of the Ircus atom is closer to the Fermi level and could form stronger ? bonding with the adsorbates. This phenomenon causes the higher binding energies of the adsorbates on the IrO2(110) surfaces than those on the RuO2(110) surfaces. In the ammonia oxidation part, calculated results show that the oxidation mechanisms on the RuO2(110) and IrO2(110) surfaces are also very similar. The ammonia oxidation reactions include three major steps: NHx dehydrogenation, H2O formation and desorption, and N-containing products formation. The oxygen-rich environment is required for ammonia oxidation over the two surfaces, because the additional Ocus atoms make the surface having sufficient oxygen species to complete the dehydrogenation. In addition, Ocus atom is also the major oxidant in the formation of oxidation products. The energetic analysis demonstrates different behavior in the formation of N2 and NO on these two surfaces. However, on both surfaces, the selectivity toward N2 and NO is dominated by the coverage of Ocus atoms on the surfaces; a higher coverage of Ocus atoms results in greater production of NO, and a lower coverage results in the production of N2.