Gotowa bibliografia na temat „Ammoniac (NH3)”

Gas sensors based on multi-walled carbon nanotube (MWCNT) for detecting gaseous molecules of ammoniac (NH3) were developed and investigated. MWCNT film was grown directly by chemical vapor deposition (CVD) method on Pt electrodes to fabricate sensor device. The CNT based – gas sensor is shown sensitively and selectively to NH3 gas at room temperature.

Cet article est consacré à la modélisation mathématique d’un système frigorifique solaire en vue de déterminer ses paramètres énergétiques. Le système en question est à absorption-diffusion fonctionnant avec le couple ammoniac-eau et l’hydrogène comme gaz inerte. Au cours de cette étude et pour la première fois, est utilisé dans le calcul de ce type de machine, un nouveau modèle mathématique pour le calcul des propriétés thermodynamiques du couple binaire ammoniac eau. A l’issue de cette étude, une analyse comparative des résultats a été effectuée sur la base des données de Bourseau.

This study investigated the removal of gases such as methane (CH4), nitrous oxide (N2O) and ammonia (NH3) from biofilters in nine anaerobic digestion plants in Germany that treat biowaste. The treatment is in form of mechanical pre-treatment, anaerobic digestion followed by a composting with or without intensive aeration. The exhaust gases from the mechanical and anaerobic steps are treated by biofilters. In average, the biofilters removed 30% of total organic carbon (TOC), 50% of non-methane volatile organic carbon (NMVOC) and 51% NH3, whereas N2O concentrations increased by 26%. For CH4 the biofilters had only a small removal effect (6%). Nghiên cứu khảo sát sự loại bỏ những khí gây hiệu ứng nhà kính như CH4, N2O và NH3 từ những bể lọc khí sinh học ở chín nhà máy xử lý rác thải hữu cơ ở nước Đức bằng các biện pháp kỵ khí và hiếu khí. Rác hữu cơ được xử lý ở nhà máy thông qua các biện pháp như tiền xử lý bằng cơ học, kỵ khí và tiếp theo là hiếu khí với công nghệ thổi khí chủ động hoặc không thổi khí chủ động. Khí thải từ các quá trình cơ học và kỵ khí được xử lý bằng biện pháp lọc khí sinh học trước khi thải ra môi trường. Trung bình, những bể lọc khí sinh học loại bỏ 30% tổng lượng carbon hữu cơ, 50% những chất carbon hữu cơ bay hơi nhưng không phải khí methane và 51% khí ammoniac. Trong khi đó, nồng độ khí N2O tăng lên 26% sau khi qua bể lọc khí sinh học. Đối với khí methane, bể lọc khí sinh học có hiệu suất loại bỏ với loại khí này rất thấp chỉ 6%.

In this study we characterized ammonia and ammonium (NH3/NH4+) transport by the rhesus-associated (Rh) glycoproteins RhAG, Rhbg, and Rhcg expressed in Xenopus oocytes. We used ion-selective microelectrodes and two-electrode voltage clamp to measure changes in intracellular pH, surface pH, and whole cell currents induced by NH3/NH4+ and methyl amine/ammonium (MA/MA+). These measurements allowed us to define signal-specific signatures to distinguish NH3 from NH4+ transport and to determine how transport of NH3 and NH4+ differs among RhAG, Rhbg, and Rhcg. Our data indicate that expression of Rh glycoproteins in oocytes generally enhanced NH3/NH4+ transport and that cellular changes induced by transport of MA/MA+ by Rh proteins were different from those induced by transport of NH3/NH4+. Our results support the following conclusions: 1) RhAG and Rhbg transport both the ionic NH4+ and neutral NH3 species; 2) transport of NH4+ is electrogenic; 3) like Rhbg, RhAG transport of NH4+ masks NH3 transport; and 4) Rhcg is likely to be a predominantly NH3 transporter, with no evidence of enhanced NH4+ transport by this transporter. The dual role of Rh proteins as NH3 and NH4+ transporters is a unique property and may be critical in understanding how transepithelial secretion of NH3/NH4+ occurs in the renal collecting duct.

The charge-transport mechanism in solid ammonium perchlorate crystal exposed to an ammonia-rich environment is studied using ab initio molecular dynamics. Ammonium perchlorate is an ionic crystal composed of NH4+ and ClO4- ; units that possesses an orthorhombic phase at T < 513 K and a cubic phase at T > 513 K. Exposure to an ammonia-rich atmosphere allows ammonia molecules to be absorbed into the crystal at interstitial sites. It has been proposed that these neutral ammonias can form short-lived N2H7+ complexes with the NH4+ ions allowing proton transfer between them, thereby enhancing the conductivity considerably. To date, however, there has been no direct evidence of this proposed mechanism. In this paper, ab initio molecular dynamics techniques are employed to explore this mechanism. By comparing computed infrared spectra of the pure and ammonia-doped crystals, we observe a significant broadening of the NH stretch peak into a lower frequency region, indicating through an experimentally verifiable observable, the formation of hydrogen bonds between NH3 and NH4+ units. This suggestion is confirmed by direct observation of N2H7+ complexes from the trajectory. Comparison of the diffusion constants of NH4+ in the pure and doped crystals yields a ratio that is comparable to the experimentally measured conductivity ratio and clearly shows an enhanced positive charge mobility. Finally, compelling evidence suggesting the possibility of an ammonia umbrella inversion following proton transfer from NH4+ and NH3 is obtained.

The compounds (NH4)3AsS4· 5 NH3 (1) and (NH4)3SbS4· 8 NH3 (2) were prepared by the reaction of Na3AsS4 and Na3SbS4 with a proton-charged ion exchange material in liquid ammonia and characterized by low temperature single crystal X-ray structure analysis. The ammonium-ammoniates show H3N-H···N-hydrogen bonds between the ammonium ion and ammonia molecules ranging from 1.86 to 2.55 Å (DHA-angles: 145 - 173°) and H3N-H···S-bonds to the thioanions between 2.36 and 2.97 Å (DHA-angles: 130 - 176°). The former of the interactions are responsible for the formation of [(NH3)2H]+, [(NH3)3H]+ and [(NH3)4H]+-complexes, the last two of which were characterized by X-ray analysis for the first time.

Abstract. This study reports abundance and distribution of gaseous NH3 and particulate NH4+ at Delhi. Gaseous NH3 and particulate NH4+ concentrations were measured during pre monsoon, monsoon and postmonsoon seasons of the years 2010 and 2011. Average concentrations of gaseous NH3 during premonsoon, monsoon and post monsoon seasons were recorded as 26.4, 33.2 and 32.5 μg m−3, respectively. Gaseous NH3 concentrations were the highest during monsoon due to decay and decomposition of plants and other biogenic material under wet conditions which emit NH3. The results showed that particulate NH4+ was always lower than the gaseous NH3 during all the seasons. The concentrations of particulate NH4+ were recorded as 11.6, 22.9 and 8.5 μg m−3 during premonsoon, monsoon and postmonsoon seasons, respectively. The percent fraction of particulate NH4+ was noticed highest during monsoon season due to increased humidity levels. On anaverage, 33.3 % of total N-NHx was present as particulate NH4+. Higher concentrations of NH3 noticed during night time may be due to stable atmospheric conditions. Study highlighted that as compared to rural sites, urban sites showed higher concentrations of gaseous NH3 in India which may be due to higher population density, human activities and poor sanitation arrangements.

Abstract. This study reports abundance and distribution of gaseous NH3 and particulate NH4&amp;plus; at Delhi. Gaseous NH3 and particulate NH4&amp;plus; concentrations were measured during pre-monsoon, monsoon and post-monsoon seasons of the years 2010 and 2011. Average concentrations of gaseous NH3 during pre-monsoon, monsoon and post-monsoon seasons were recorded as 26.4, 33.2 and 32.5 μg m−3, respectively. Gaseous NH3 concentrations were the highest during monsoon, thought to be due to decay and decomposition of plants and other biogenic material under wet conditions, leading to increased NH3 emission. The results showed that particulate NH4&amp;plus; was always lower than the gaseous NH3 during all the seasons. The concentrations of particulate NH4&amp;plus; were recorded as 11.6, 22.9 and 8.5 μg m−3 during pre-monsoon, monsoon and post-monsoon seasons, respectively. The percent fraction of particulate NH4&amp;plus; was noticed to be highest during the monsoon season, which is attributed to increased humidity levels favouring partitioning into the aerosol phase. On an average, 33.3% of total N-NHx was present as particulate NH4&amp;plus;. Higher concentrations of NH3 noticed during night time may be due to stable atmospheric conditions. The study highlighted that, as compared with rural sites, urban sites showed higher concentrations of gaseous NH3 in India, which may be due to higher population density, human activities and poor sanitation arrangements.

Ammonium accumulates in the renal medullas of antidiuretic mammals. The accumulation process is thought to involve countercurrent multiplication, energy-dependent recycling between the ascending and descending limbs of Henle's loop. To investigate the role of the long-loop thin descending limb (LDL) in countercurrent multiplication of ammonium, we have perfused outer medullary and inner medullary subsegments of the chinchilla LDL (and inner medullary subsegments of rat LDL) in vitro and measured the fluxes of total ammonia and total CO2. No spontaneous fluxes of total ammonia or total CO2 occurred in the absence of imposed concentration gradients. When transepithelial concentration gradients were imposed, passive total ammonia and total CO2 transport were observed in all subsegments, although the permeabilities varied with distance along the descending limb. Passive total ammonia transport occurred through a combination of NH3 and direct NH4+ permeation. The outer medullary segment was the most permeable to NH4+. The deep inner medullary segment was the most permeable to bicarbonate. Addition of carbonic anhydrase to the lumen accelerated passive NH3 entry in the outer medullary LDL, indicating that little or no luminal carbonic anhydrase is endogenously present. The passive secretion of NH4+ and NH3 into the LDL may contribute to the countercurrent multiplication of ammonium in the rodent renal medulla.

The use of mineral nitrogen (N) fertilizers is associated with significant nitrogen loss through the volatilization. Ammonia (NH3) emissions are common from fertilizers with amide (NH2) and ammonium (NH4) nitrogen forms applied to the soil surface without incorporation. The objective of the laboratory and greenhouse pot experiments was to verify the hypothesis that liquid mineral fertilizers and fertilizer solutions containing N-NH2 and N-NH4 applied to the soil surface in combination with natural hydroabsorbents (NHAs) will reduce the volatilization of nitrogen. The effect of NHAs addition to urea ammonium nitrate (UAN) fertilizer and urea, ammonium nitrate (AN) and ammonium sulphate (AS) solutions was evaluated in a laboratory experiment. The effect of the two types of NHAs (acidic and neutral) was compared with the control (UAN) and its mixture with the commercially used urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). The proportion of volatilized NH3 of the total N from the examined fertilizers applied to the soil surface was determined by the titration method. Subsequently, the effect of fertilization with UAN and its mixture with NHAs and NBPT on the growth of maize under the drought conditions was verified in a greenhouse pot experiment. While the addition of NBPT resulted in a reduction of NH3 emission for the fertilizers containing NH2 (UAN, urea solution), a decrease in volatilization after the addition of both acidic and neutral NHA was observed especially for UAN. A reduction in ammonia emission was also observed for AS after the addition of acidic NHA. The addition of both NHAs and NBPT to UAN increased the utilization of nitrogen from the applied fertilizer, which was reflected by an increase in chlorophyll content and increased CO2 assimilation by maize plants grown under the drought stress. UAN fertilizer combined with acidic NHA and NBPT significantly increased aboveground biomass production and root system capacity of maize. Significant increases in UAN nitrogen recovery were observed for all examined additives (UI and both types of NHAs). In addition to the known effects of hydroabsorbents, especially their influence on soil physical and biological properties and soil water retention, the effect of NHAs application in combination with UAN and AS solutions on the reduction of gaseous N loss, maize plant growth and fertilizer nitrogen recovery was found.

Nous avons étudié les transferts inélastiques rotationnels induits par collisions dans l'ammoniac perturbé par H₂et He, systèmes d’intérêt astrophysique et fondamental (test du potentiel intermoléculaire). Nous avons mené cette étude par deux méthodes différentes : - Profil de raies d'absorption infrarouge - Double résonance infrarouge-infrarouge résolue dans le temps. La première nous a permis de déterminer les sections efficaces d'élargissement par pression et de couplage intradoublet (très sensible au potentiel intermoléculaire) en fonction du nombre quantique de rotation j et de la température dans la bande v₄et l'état vibrationnel fondamental. Afin de comprendre, d'une part, la différence entre les résultats obtenus en micro-onde et ceux de la bande v₄, et d'autre part pour effectuer une meilleure comparaison entre l'expérience et la théorie, nous avons mesuré des sections efficaces d'élargissement par pression dans l'état vibrationnel fondamental. Les résultats expérimentaux ainsi que les calculs théoriques semi-classiques effectués en collaboration avec G. Billing ont permis d'aboutir aux conclusions suivantes : - Différence entre la collision NH₃- He et NH₃- H₂para. -Mise en évidence d'un effet vibrationnel dans la collision NH₃- H₂ -Rôle de l'excitation rotationnelle de H₂lors de la collision. - Désaccord entre les valeurs expérimentales et théoriques du coefficient de couplage dans la collision NH₃- He. La deuxième méthode consiste à créer une perturbation de populations d'un niveau rotationnel sélectionné à l'aide d'un pulse laser (laser à C0₂TEHP), puis à détecter l'absorption transitoire avec un laser continu (diode laser). Cette étude permet de déterminer les sections efficaces collisionnelles niveau par niveau. En sondant les niveaux voisins du niveau pompé, on pourra déterminer les règles de sélection collisionnelles
We 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

L’ammoniac (NH3) est un polluant atmosphérique émis à 80 % par l’agriculture, qui contribue à l’eutrophisation et l’acidification des milieux naturels. C’est aussi un précurseur de particules fines (PM2.5) nocives pour la santé. Malgré ce rôle scientifique et sociétal majeur, nos connaissances sur l’ammoniac atmosphérique restent très limitées. La mesure du profil vertical de NH3 constitue l’une des clés permettant d’approfondir ces connaissances. C’est pourquoi, l’objectif principal de cette thèse est de développer un instrument de mesure de l’ammoniac embarquable dans un ballon captif afin de mesurer ces profils verticaux. Un état de l’art de la mesure de NH3 a d’abord été réalisé à travers l’analyse des données de la campagne AMICA (Analyse Multi-Instrumentale des Concentrations d’Ammoniac) à l'automne 2021. Il a montré la nécessité de concevoir un instrument sans système de prélèvement pour éviter les biais liés à l’adsorption de NH3. Afin de tester et valider les techniques de spectroscopie infrarouge (DAS et WMS) envisagées pour la mesure de NH3, un premier instrument pour la mesure du CO2 (premier gaz à effet de serre d'origine anthropique) a été développé et a permis de réaliser des mesures de profils verticaux. NH3 étant bien plus difficile à détecter que le CO2, une cellule optique à grande longueur de parcours a été conçue afin d’améliorer la sensibilité de l’instrument. Plus généralement, les outils conçus et mis en place au cours de cette thèse peuvent s’appliquer à la mesure de toutes les espèces atmosphériques d’intérêt et en particulier à celles présentes à l’état de traces
Ammonia (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

Ce travail avait pour but de déterminer les paramètres des raies d’absorption de la molécule d’ammoniac en vue d’applications atmosphériques. A ce sujet, nous avons mesuré, à température ambiante, les intensités et les coefficients d’élargissement et de déplacement collisionnels des raies des bandes v1, v3, 2v4, et 4v2 dans la région spectrale 3050-3600 cm-1 de NH3 auto-perturbé. Ces mesures ont été effectuées dans un grand nombre de branches de ces bandes avec une très grande précision à l’aide d’un spectromètre infrarouge à transformée de Fourier à haute résolution (0.008 cm-1). Ces paramètres spectroscopiques ont été déterminés à l’aide d’une technique d’ajustement multi-pression utilisant deux profils différents : un profil de Voigt et un profil de Rosenkranz. Le manuscrit comporte cinq parties. La première partie concerne les propriétés spectroscopiques de l’ammoniac. La deuxième partie est dédiée à l’appareillage, avec la description du spectromètre IRTF Bruker IFS125HR. Dans la troisième partie, nous exposons les résultats des intensités et des auto-élargissements de raies isolées, qui sont extrait à partir des spectres enregistré, des bandes v1, v3,2v4 et 4v2 de NH3. La quatrième partie présente les résultats obtenus sur les déplacements de raies et les effets d’interférence entre les composantes des doublets des bandes v1 et v3 de NH3.Pour interpréter les résultats des mesures de largeurs de raies du système collisionnel NH3 auto-perturbé, nous allons présenter dans le chapitre 5 le formalisme adopté pour le calcul de ces largeurs. Une comparaison entre les largeurs calculées et mesurées permet de tester la validité du formalisme utilisé
The 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

Les moteurs Diesels connaissent un intérêt récent tout particulier car ils rejettent moins de CO2 que les moteurs essences à puissance égale, du fait qu’ils travaillent en mélange pauvre (en excès d’oxygène). Récemment, des catalyseurs de réduction catalytique sélective (SCR) déposés sur des filtres à particules diesel (FAP) ont été développés pour les applications automobiles en raison de leur capacité à réduire simultanément les émissions de NOx et de particules. Une telle mise en œuvre nécessite une résistance thermique améliorée du catalyseur SCR du fait des exothermes liés à la régénération périodique du FAP. Le but de ce travail est de proposer un catalyseur pour la réduction des NOx par NH3 actif après vieillissement à haute température. La première partie de ce manuscrit détaille les modifications du catalyseur CeV0.95W0.05O4 en ajoutant des éléments de terres rares (Pr3+, Gd3+, Tb3+, Er3+). Le catalyseur le plus prometteur obtenu par la substitution partielle du cérium par des terres rares était finalement le catalyseur Ce0.5Er0.5V0.95W0.05O4. Une substitution partielle du cérium par de l’erbium permet d’obtenir un gain d’activité après vieillissement à 600 et 850°C attribué à la capacité de l'erbium à favoriser la stabilité thermique des catalyseurs contenant du vanadium. Ce comportement pourrait également être corrélé aux caractéristiques de la liaison Er3+_O_V5+ et à leur capacité à modifier les caractéristiques de la liaison V_O et les propriétés acide/base de surface. Le catalyseur Ce0.5Er0.5V0.95W0.05O4, la formulation optimisée, permet d’obtenir une conversion de NOx supérieure à 80% entre 250 et 400°C en condition Fast-SCR après un vieillissement à 850°C
Diesel 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

Les moteurs Diesels connaissent un intérêt récent tout particulier car ils rejettent moins de CO2 que les moteurs essences à puissance égale, du fait qu’ils travaillent en mélange pauvre (en excès d’oxygène). Récemment, des catalyseurs de réduction catalytique sélective (SCR) déposés sur des filtres à particules diesel (FAP) ont été développés pour les applications automobiles en raison de leur capacité à réduire simultanément les émissions de NOx et de particules. Une telle mise en œuvre nécessite une résistance thermique améliorée du catalyseur SCR du fait des exothermes liés à la régénération périodique du FAP. Le but de ce travail est de proposer un catalyseur pour la réduction des NOx par NH3 actif après vieillissement à haute température. La première partie de ce manuscrit détaille les modifications du catalyseur CeV0.95W0.05O4 en ajoutant des éléments de terres rares (Pr3+, Gd3+, Tb3+, Er3+). Le catalyseur le plus prometteur obtenu par la substitution partielle du cérium par des terres rares était finalement le catalyseur Ce0.5Er0.5V0.95W0.05O4. Une substitution partielle du cérium par de l’erbium permet d’obtenir un gain d’activité après vieillissement à 600 et 850°C attribué à la capacité de l'erbium à favoriser la stabilité thermique des catalyseurs contenant du vanadium. Ce comportement pourrait également être corrélé aux caractéristiques de la liaison Er3+_O_V5+ et à leur capacité à modifier les caractéristiques de la liaison V_O et les propriétés acide/base de surface. Le catalyseur Ce0.5Er0.5V0.95W0.05O4, la formulation optimisée, permet d’obtenir une conversion de NOx supérieure à 80% entre 250 et 400°C en condition Fast-SCR après un vieillissement à 850°C
Diesel 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

Conception d'un dispositif experimental dans le but d'etudier les proprietes physiques et cinetiques des systemes bacl::(2)/nh::(3) et cacl::(2)/nh::(3). Mesures de vitesses de desorption et d'absorption. Modele d'optimisation des processus et experimentation d'un prototype de refrigeration a capteur solaire plan

La Reduction Catalytique Sélective (SCR) par l’ammoniac est un procédé qui est commercialement utilisé pour l’élimination des oxydes d’azote (NOx) issus des moteurs Diesel afin de répondre aux exigences des normes européennes concernant les émissions. Pour pouvoir mieux traiter les NOx, surtout à froid, la combinaison du catalyseur SCR à base de zéolithe échangée au Cu (Cu-Zéolithe) et le filtre à particules (SCRF) représente un avantage à son rapprochement du moteur. Néanmoins, la combinaison peut avoir aussi des inconvénients, lors de la régénération en continue du filtre à particules, le catalyseur SCRF sera soumis à de multiples occurrences thermiques et à de possible empoisonnement par le carburant et l’huile moteur durant toute la vie du système de post-traitement en véhicule. Etant donné que la législation européenne exige que le système de post-traitement soit opérationnel et efficace jusqu’à 160.000km, il est donc important de comprendre les phénomènes engendrés par le vieillissement hydrothermal du SCRF afin de pouvoir l’améliorer. Dans le cadre de ce travail, des simulations du vieillissement hydrothermal dans un four de laboratoire et en parallèle un vieillissement réel d’environ 120.000km d’une ligne de post-traitement comprenant le SCRF ont été réalisés. Les différents résultats ont permis de comprendre le mécanisme de dégradation de la performance du catalyseur à base de Cu-Zéolithe lié au traitement hydrothermal et de pouvoir corréler un vieillissement réel en véhicule à un vieillissement accéléré au four. De plus, des techniques rapides de caractérisation permettant de détecter l’état de vieillissement d’un catalyseur SCRF ont été sélectionnées. Finalement, un modèle mathématique basé sur les résultats expérimentaux a permis de décrire la dégradation de la capacité de stockage de l’ammoniac du catalyseur SCRF avec le traitement hydrothermal
The 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

ENGLISH:

The 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

La prise de conscience de l'importance de la gestion des déchets et de la préservation des ressources a conduit de plus en plus d'acteurs du monde agricole à s'intéresser au compostage comme mode de traitement d'effluents d'élevage ou de boues de stations d'épuration. Les filières d'utilisation de ces substrats, épandage, compostage ou autre, doivent donc être comparées. On sait en effet que l'agriculture est responsable d'une part importante des émissions d'ammoniac (NH3) et de protoxyde d'azote (N2O) et ainsi, indirectement ou directement, de l'augmentation de la concentration de N2O dans l'atmosphère. Trois séries d'expérimentations ont été menées respectivement sur des mélanges d'écorces de peuplier et de fientes de poules pondeuses, sur du fumier de poulet sans ou avec additifs et sur un mélange de paille et de boues de station d'épuration rurale, en parallèle avec un nouveau mélange d'écorces et de fientes. La première a permis de mesurer les émissions de gaz azotés d'un andain (25 m3) en cours de compostage. Elles étaient de 50% environ de l'azote initial sous forme N- NH3 et de moins de 1% sous forme N-N2O. La production de N2O était associée à des activités de nitrification/dénitrification et avait principalement lieu en phase de maturation. La seconde a révélé, pour du compostage de courte durée (1,5 mois) et en taille expérimentale (2 m3), les conditions dans lesquelles les émissions de NH3 et de N2O étaient les plus fortes ou les plus faibles et lesquelles favorisaient l'activité de dénitrification des micro-organismes. L'augmentation du rapport carbone/azote et l'addition de composés ou microorganismes adéquats font passer les pertes en NNH3 de 55 à 7% de l'azote initial. Leur effet sur la libération de N2O (0,2-0,9%) dépend de nombreux facteurs. La troisième a montré que les andains de compostage (10 et 25 m3) devaient être considérés comme des écosystèmes à part entière composés de différents compartiments (grossièrement entrée, fond, sortie et croûte) où les populations microbiennes s'organisent différemment, l'entrée étant productrice de N2O, le fond et la sortie, producteurs, en équilibre ou consommateurs suivant les moments. La taille de l'andain en expérimentation est donc une donnée capitale pour considérer les résultats comme représentatifs de la réalité.

AbstractAmmonia is a crucial hydrogen carrier. This paper explores small-scale green ammonia production from two-stage sorption-enhanced gasification of biomass. ASPEN Plus was used to calculate the mass and energy balance of two novel process designs; configuration (a) employs fractional flue gas recycling to supply nitrogen for producing carbon-neutral ammonia without air separation, and configuration (b) uses air separation to produce carbon-negative ammonia by efficiently capturing CO2. The mass balance shows that the ammonia yield of configuration (a) is about 5% higher than that of configuration (b). The energy analysis shows that additional biomass fed to the combustor is the primary energy penalty in configuration (a), while the primary energy penalty in configuration (b) is from the electricity consumption by the ASU and CO2 compressor. The energy penalty for configuration (a) is considerably higher than that for configuration (b); hence, configuration (b) has lower energy consumption.(36.4 GJ/t NH3 vs. 40.2 GJ/t NH3). Overall, configuration (b) is superior to configuration (a) from a techno-environmental standpoint.

Abstract Ammonia (NH3) has garnered considerable attention in recent years as a promising carbon-free hydrogen carrier fuel for internal combustion engines. However, directly using pure ammonia in compression-ignition engines poses challenges. To facilitate NH3 ignition, high-activity fuels are often employed to ignite the premixed NH3/air mixture and initiate combustion. This study specifically focuses on the ignition process of binary mixtures of NH3 and dimethyl ether (DME), considering that DME is a carbon-neutral high-activity fuel. By conducting zero-dimensional reaction kinetics analysis, we compare the ignition processes of DME and NH3/DME mixtures. The results reveal that the addition of NH3 has minimal impact on the control mechanism of DME’s two-stage ignition process. DME still heavily relies on the proliferation of OH radicals in the low-temperature oxidation pathway, releasing heat during the reaction progression. As the temperature increases, the low-temperature oxidation branching pathways are gradually replaced by chain propagation pathways, resulting in a decrease in overall reaction activity. The reactivity and temperature rise rate of the reaction system is then controlled by the H2O2 loop mechanism prior to the thermal ignition. However, the presence of ammonia noticeably extends the ignition delay period of DME. Ammonia competes with OH radicals, essential for DME oxidation, thereby inhibiting DME ignition. Additionally, as the ignition reaction advances, the involvement of NH3 kinetics increases. For instance, nitrogen-containing species generated from NH3 oxidation, such as NO, NO2, and NH2, react with CH3OCH2 to form CH3OCHO, reducing the flux through the low-temperature oxidation pathway of DME. While ammonia reaction pathways also generate OH radicals, this comes at the expense of HO2 radicals and H radicals, ultimately leading to H2O2 production. Overall, these findings clearly demonstrate the substantial impact of ammonia addition on the ignition process of DME, emphasizing the necessity for further fundamental research to enhance our understanding of NH3/DME binary fuel ignition. Such insights are pivotal for improving the design and operation strategies of NH3/DME dual-fuel engines, thereby improving engine efficiency and reliability.

Ammonia is an important atmospheric trace molecule in the atmospheric transformation of sulfur and nitrogen compounds. Because it is a base, NH3 dissolved in water droplets as the ammonium ion promotes increased solubilities of sulfate and nitrate ions. Ammonia, therefore, is suspected of playing a role in the formation of acid rain. Infrared lidars based on the CO2 laser could be used to remotely monitor ammonia concentrations in the atmosphere.

Abstract With the application of selective catalytic reduction (SCR) technology, the operation of rotary air preheaters is faced with a challenge, the fouling problem caused by ammonium bisulfate (ABS). In previous studies, within the operational temperature range of the preheater, the gaseous ammonia and sulfur trioxide (or H2SO4) in the flue gas can react to form ABS and ammonium sulfate (AS). The initial condensation temperature of ABS might be over predicted due to the effect of the formation of AS, which has a higher initial formation temperature than ABS. In this study, the effects of the deposition temperature, ammonia-sulfur molar ratio and molar product of inlet flue gas on the deposition characteristics of inducing ash deposition compounds were experimentally studied to provide guidance to prevent fouling and corrosion of rotary air preheaters. The results show that the main path to generate ABS is the reaction between H2SO4 and NH3. With the increase in the deposition temperature, the contents of NH4+ and SO42− in the sediments decrease continuously, and the proportion of AS deposition increases. On the contrary, with temperature decreasing, more ABS is deposited. When the molar ratio of ammo-sulfur in the inlet flue gas increases, the proportion of AS in the sediments increases, and the deposition rate also gradually increases. When the ammo-sulfur product in the inlet flue gas increases, the concentrations of both NH4+ and SO42− in the sediments increased in a nearly consistent trend. The variations of the ratio and deposition rates of the two ions in the sediments were not obvious. The ratio of NH4+ and SO42− remains at about 1.2, and the sediment is mainly ABS.

Part of TRU waste includes a large amount of nitrate salt, the effects of which have to be evaluated in a safety assessment of co-location disposal with high level radioactive waste (HLW). High concentrations of nitrate ions from TRU waste might affect the solubility of different radionuclides in the HLW. In the current study, the effects of nitrate salt on radionuclide solubility were investigated experimentally. Solubility experiments of important and redox sensitive radionuclides, Tc(IV), Np(IV) and Se(0), were performed using various concentrations of sodium nitrate (NaNO3) and of Np(V) in NaNO3 solutions to investigate complex formation with NO3− ions. Solubility experiments of Pd(II), Sn(IV) and Nb(V) using ammonium chloride (NH4Cl) solution were also undertaken to investigate complex formation with NH3/NH4+ ions. No significant solubility enhancement was observed for Np and Se. Tc solubility in ≥0.1 mol/dm3 NaNO3 solution increased due to oxidation by nitrate ions. An increase of Np(V) solubility was expected by the chemical equilibrium model calculation with JNC-TDB, however, solubility enhancement by complex formation of Np(V) with nitrate ions was not observed. Solubility enhancement by complex formation of Sn and Nb were also not observed, only Pd solubility was increased by complex formation with NH3/NH4+ ions.

Abstract The authors conducted NH3 and diesel fuel dual fuel combustion experiments using both large and small single-cylinder diesel engines and investigated its combustibility and emission changes by adding H2. In addition, the small engine was operated by supplying reformed gas containing H2, which was produced using a device to reform NH3 into H2. Co-combustion of NH3 and diesel fuel with large and small single-cylinder engines showed similar trends in the change of emissions. In particular, N2O emissions tended to decrease when the NH3 energy fraction was higher in the cases of the large engine. The combustion-assisting effect of H2 was obtained when H2 was mixed into the charge air of NH3/diesel dual fuel mode with the large and small single-cylinder engines. The addition of H2 resulted in a reduction in unburned NH3 and a change in N2O emissions. Reduction in N2O emissions was achieved by increasing the amount of supply H2, particularly for the large engine. The small engine was operated by supplying reformed gas. This allowed unburned NH3 to drastically decrease. It was also found that N2O emission can be generated when NH3 remains in the reformed gas. The NH3 reforming system has achieved the target H2 flow rate, and the effectiveness of the proposed reforming system has been demonstrated. This research provided valuable insights for the design of an NH3 reforming system suitable for marine engines.

It is well known that ammonia (NH3) combustion does not produce carbon dioxide (CO2) causing global warming. Therefore, NH3 has received much attention as an alternative diesel fuel for internal combustion engines. On the other hand, it has been reported that the exhaust gas of diesel engine fumigated with NH3 contains unburned NH3 with toxicity for humans and nitrous oxide (N2O) with strong global warming effect. Hence the NH3 and N2O emissions should be reduced to prevent the human health damage and global warming. The aim of this study was to develop the combustion strategies for reducing the unburned NH3 and N2O emissions on diesel engine fumigated with NH3. The experimental results indicated that the higher temperature combustion of NH3 prevents the N2O production and allows itself to react well. From the numerical simulation results, hydrocarbon combustion decomposes NH3 and N2O in ignition processes.

Abstract Gas nitriding has been performed in many ways with many variations over the years (using NH3 only, NH3 + dissociated NH3, and NH3 + N2). Practical heat treating today demands lower costs and gas and energy consumption. With the challenges of ammonia storage, its costs and emissions, the ZeroFlow process reduces ammonia gas consumption and still offers the same capability to affect the nitrided layer, resulting in lower emissions of ammonia and greenhouse gases. Prior analysis has shown that ZeroFlow control allows control of not only the nitriding potential, but also phase composition of the nitrided layer, its thickness and the constituents of the atmosphere used for nitriding. Tremendous experience via actual commercial production has proven that this method of gas nitriding, and the atmosphere used, still allows for precision in controlling growth kinetics of the nitrided layer. The impact on the ammonia consumption and emissions is significant.

Abstract Recent findings from the US Energy Information Administration (EIA) project an increase in domestic fossil fuel consumption (e.g., petroleum, natural gas) and global greenhouse gas (GHG) emissions through 2050 [1]. Consequently, advanced combustion research aims to identify fuels to mitigate fossil fuel consumption while minimizing exhaust emissions. Ammonia (NH3) is one of these candidates, as it has historically been shown to provide high energy potential and zero carbon emission (CO and CO2) [2]. As a hydrogen (H2) carrier, NH3 serves as a possible solution to the U.S. Department of Energy’s (DOE) Hydrogen Program Plan by providing efficient H2 storage and conservation capabilities [3]. As a result, applied turbine-combustion research of NH3 and H2 fuel has been conducted to identify combustion performance parameters that aid in the design of sustainable turbomachinery [4]. One of these key combustion parameters is the laminar burning speed (LBS). While abundant literature exists on the combustion of NH3 and H2 fuels, there is not sufficient evidence in high-pressure environments to provide a comprehensive understanding of NH3 and H2 combustion phenomena in turbine-combustor settings. To advance the state of the knowledge, NH3, and H2 mixtures were ignited in a spherical chamber across a range of equivalence ratios at 296 K and 5.07 Bar (5 atm) to understand their flame characteristics and LBS which was determined using a multizone constant-volume method. The experimental conditions were selected according to primary turbine-combustor conditions, as much research is needed to support NH3-H2 applicability in turbomachinery for power generation. The effect of H2 addition to NH3 fuel was observed by comparing the LBS for various NH3-H2 mixture compositions. Experimental results revealed increased LBS values for H2 enriched NH3, with the maximum LBS occurring at stoichiometry. The experimental data were accurately predicted by the UCF NH3-H2 mechanism developed for this investigation, while NUI 1.1 simulations overestimated recorded LBS data by a significant margin. This study demonstrates and quantifies the enhancing effect of H2 addition to NH3 fuels via LBS and strengthens the literature surrounding NH3-H2 combustion reactions for future work.

Abstract Ammonia has been proposed as a hydrogen carrier and a potential alternative fuel to achieve low-carbon emissions. Due to its high ignition energy, limited flammable range, and low heating value compared to hydrogen and typical hydrocarbon fuels, it is challenging to sustain stable ammonia combustion. Blending ammonia with natural gas can increase the possibility of combustion applications. This work is to investigate the combustion performance of a micro gas turbine combustor with CH4/NH3 fuel blends. Results indicated the flame temperature declined with increasing NH3 mole fractions at constant fuel flow rates due to lower heating value of ammonia. To maintain the same power output with increasing NH3 contents, the mass flow rates of the fuel blends were raised, which pushed the flame downstream and resulted in severe temperature fluctuation at combustor exit. At higher NH3 fractions, the high-temperature regions shrank again because of lower residence time for any significant reactions. NOx emission was increased due to fuel-NOx production with NH3 addition. However, the non-monotonic trend of NO emission indicated a competition between thermal-NO and fuel-NO productions. Further considerations of flame stabilization and dilution strategy are essential for the implementation of the fuel blends in this micro gas turbine.

In this paper, the potential benefits and technical advantages of using ammonia as a green fuel for transportation are analyzed based on performance indicators including the system effectiveness, the driving range, fuel tank compactness, and the cost of driving per km. Similar to hydrogen, ammonia is a synthetic product that can be obtained thermally, physically, chemically or biologically either from fossil fuels, biomass, or other renewable sources and can be used as a clean fuel. The refrigeration effect of ammonia is another advantage of it and is included in the efficiency calculations. The cooling power represents about 7–10% from the engine power, being thus a valuable side benefit of ammonia’s presence on-board. If the cooling effect is taken into consideration, the system’s effectiveness can be improved by about 20%. It is shown that if a medium size hydrogen car converted to NH3, it becomes more cost effective per driving range as low as CN$3.2/100 km.

The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.

The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.

The purpose of this note is to document data sources and steps used to develop the air pollution database for the GTAP Data Base Version 10A. Emissions for nine substances are reported in the database: black carbon (BC), carbon monoxide (CO), ammonia (NH3), non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx), organic carbon (OC), particulate matter 10 (PM10), particulate matter 2.5 (PM2.5) and sulfur dioxide (SO2). The dataset covers four reference years – 2004, 2007, 2011 and 2014. EDGAR Version 5.0 database is used as the main data source. To assist with emissions redistribution across consumption-based sources, IIASA GAINS-based model and IPCC-derived emission factors are applied. Each emission flow is associated with one of the four sets of emission drivers: output by industries, endowment by industries, input use by industries and household consumption. In addition, emissions from land use activities (biomass burning) are estimated by land cover types. These emissions are reported separately without association with emission drivers.

Ammonia waste removal in recirculating aquaculture systems is typically accomplished via the action of nitrifying bacteria in specially designed biofilters that oxidize ammonia to produce nitrate. In the majority of these systems nitrate is discharged to the environment through frequent water exchanges. As environmental considerations have made it necessary to eliminate nitrate release, new strategies for nitrate consumption are being developed. In the funding period we showed that ammonia removal from wastewater could take place by an anaerobic ammonia oxidation process carried out by bacterial Planctomycetessp. Referred to as “anammox”, this process occurs in the absence of an organic source and in the presence of nitrite (or nitrate) as an electron acceptor as follows: NH₃ + HNO₂ -> N₂ + 2H₂O. Annamox has been estimated to result in savings of up to 90% of the costs associated with was wastewater treatment plants. Our objective was to study the applicability of the anammox process in a variety of recirculating aquaculture systems to determine optimal conditions necessary for efficient ammonia waste removal. Both seawater and freshwater systems operated with either conventional aerobic treatment of ammonia to nitrate (USA) or, in addition, denitrifying biofilters as well as anaerobic digestion of sludge (Israel) were tested. Molecular tools were used to screen and monitor different treatment compartments for the presence of Planctomycetes. Optimal conditions for the enrichment of the anammox bacteria were tested using laboratory scale biofilters as well as a semi-commercial system. Enrichment studies resulted in the isolation of some unique heterotrophic bacteria capable of plasmid-mediated autotrophic growth in the presence of ammonia and nitrite. Our studies have not only demonstrated the presence and viability of Planctomycetes spp. in recirculating marine and freshwater systems biofilter units but also demonstrated the applicability of the anammox process in these systems. Using our results we have developed treatment schemes that have allowed for optimizing the anammox process and applying it to recirculating systems.

The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.