Academic literature on the topic 'N2O reaction gas'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'N2O reaction gas.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "N2O reaction gas"
1
Lee, Sang Ji, Jae Geun Yun, Han Min Lee, Ji Yeop Kim, Jin Han Yun, and Jung Goo Hong. "Dependence of N2O/NO Decomposition and Formation on Temperature and Residence Time in Thermal Reactor." Energies 14, no. 4 (February 22, 2021): 1153. http://dx.doi.org/10.3390/en14041153.
Full textAbstract:
Nitrogen dioxide (N2O) is a greenhouse gas that is harmful to the ozone layer and contributes to global warming. Many other nitrogen oxide emissions are controlled using the selective non-catalytic reaction (SNCR) process, but N2O reduction methods are few. To avoid future air pollution problems, N2O reduction from industrial sources is essential. In this study, a N2O decomposition and NO formation under an argon atmospheric N2O gas mixture were observed in a lab-scale SNCR system. The reaction rate and mechanism of N2O were calculated using a reaction path analyzer (CHEMKIN-PRO). The residence time of the gas mixture and the temperature in the reactor were set as experimental variables. The results confirmed that most of the N2O was converted to N2 and NO. The change in the N2O reduction rate increased with the residence time at 1013 and 1113 K, but decreased at 1213 K due to the inverse reaction. NO concentration increased with the residence time at 1013 and 1113 K, but decreased at 1213 K owing to the conversion of NO back to N2O.
2
Sheldon, JC, RAJ Ohair, KM Downard, S. Gronert, M. Krempp, CH Depuy, and JH Bowie. "A Potential Surface Map of the H-/N2O System. The Gas Phase Ion Chemistry of HN2O-." Australian Journal of Chemistry 48, no. 2 (1995): 155. http://dx.doi.org/10.1071/ch9950155.
Full textAbstract:
Dunkin, Fehsenfeld and Ferguson have reported that the gas phase reaction between H- and N2O in a flowing afterglow instrument forms HO- and N2 with medium efficiency. The potential surface (UMP2-FC/6-311++G**//RHF/6-311++G**) for the H-/N2O system confirms this to be the predominant reaction following initial approach of H- towards the central nitrogen of N2O to form unstable intermediate [H-(N2O)]. The intermediate then decomposes to HO- and N2 via a deep channel. The potential surface also shows the direct formation of adducts -O-+N(H)=N- and cis HN=NO-. However, these are formed with excess energy: the former converts principally into reactants, while the latter decomposes to HO- and N2. Ions having the formula 'HN2O-' may be formed in the gas phase by the reactions ( i ) HNO-+N2O → HN2O-+NO, and (ii) NH2-+Me3CCH2ONO → HN2O-+Me3CCH2OH. The product anion is stabilized by removal of some of its excess energy by the eliminated neutral. Evidence is presented which indicates that the product is either cis or trans HN=NO-, or a mixture of both. The characteristic ion molecule reaction of HN=NO- involves oxidative oxygen transfer to suitable neutral substrates. For example: HN2O-+CS2 → HS-+N2+COS.
3
Smith, D. M., W. F. Welch, S. M. Graham, A. R. Chughtai, Brian G. Wicke, and Karen A. Grady. "Reaction of Nitrogen Oxides with Black Carbon: An FT-IR Study." Applied Spectroscopy 42, no. 4 (May 1988): 674–80. http://dx.doi.org/10.1366/0003702884429247.
Full textAbstract:
Qualitative and quantitative studies of the reaction of black carbon with the oxides of nitrogen, including NO, NO2/N2O4, N2O, and N2O3, have been carried out with the use of Fourier transform infrared spectroscopy (FT-IR). The active reactant is shown to be NO2, whether it acts as a disproportionation product or as an impurity in the gas under study. FT-IR spectra of the surface species identify them as resulting from reaction of carbon with NO2. For paraffin candle soot which was exposed simultaneously to oxygen atoms, and nitric oxide at 298 K, the surface species also are due to NO2, formed by oxidative adsorption of NO on the soot surface.
4
Li, Songfeng, Chunhua Zhang, Ao Zhou, Yangyang Li, Peng Yin, Chunfang Mu, and Jinyuan Xu. "Experimental and kinetic modeling study for N2O formation of NH3-SCR over commercial Cu-zeolite catalyst." Advances in Mechanical Engineering 13, no. 4 (April 2021): 168781402110106. http://dx.doi.org/10.1177/16878140211010648.
Full textAbstract:
In this paper, a systematic experimental and kinetic model investigation was conducted over Cu-SSZ-13 catalyst to study the DeNOx efficiency and N2O formation for selective catalytic reduction of NOx with NH3 (NH3-SCR). The kinetic model was developed for various reactions to take place in the NH3-SCR system, including NH3 adsorption/desorption, NH3 oxidation, NO oxidation, standard SCR, fast SCR, slow SCR and N2O formation reactions. In addition, the reaction of N2O formation from NH3 non-selective oxidation was taken into account. All the experiments were performed in a flow reactor with a feed stream near to the real application of diesel engine vehicles exhaust. The current model can satisfactorily predict the steady state conversion rate of various species at the reactor outlet and the effect of gas hourly space velocities and ammonia nitrogen ratio on N2O formation. The results show that the kinetic model can simulate the reaction process of the Cu-SSZ-13 catalyst well. This is significant for the optimization of NH3-SCR system for achieving the higher DeNOx efficiency and the lower N2O emission.
5
Yamazaki, T., T. Hozuki, K. Arai, S. Toyoda, K. Koba, T. Fujiwara, and N. Yoshida. "Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria." Biogeosciences 11, no. 10 (May 21, 2014): 2679–89. http://dx.doi.org/10.5194/bg-11-2679-2014.
Full textAbstract:
Abstract. Nitrous oxide (N2O) is a potent greenhouse gas and produced in denitrification and nitrification by various microorganisms. Site preference (SP) of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathways. To determine representative SP values for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO) purified from two species of ammonia oxidizing bacteria (AOB), Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR) from Paracoccus denitrificans. The SP value for NOR reaction (−5.9 ± 2.1‰) showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰) was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2–) reduction (which is followed by NO reduction) to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for the NH2OH oxidation pathway possibly due to a small contribution of NO2– reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.
6
Yamaguchi, Naoya, Eichi Nagatomi, Takahiro Kato, Koichiro Ohishi, Yasuhiro Tamayama, and Kanji Yasui. "Effects of N2O addition on the properties of ZnO thin films grown using high-temperature H2O generated by catalytic reaction." MRS Proceedings 1633 (2014): 61–67. http://dx.doi.org/10.1557/opl.2014.20.
Full textAbstract:
ABSTRACTThe effects of N2O gas addition on the properties of zinc oxide films grown on a-plane (11-20) sapphire (a-Al2O3) substrates were investigated, using a chemical vapor deposition method based on the reaction between dimethylzinc and high-energy H2O produced by a Pt-catalyzed H2-O2 reaction. By employing an optimal N2O gas pressure, both the film crystallinity and crystal orientation were improved. Subsequent to treatment with N2O, the electron mobility of films at room temperature increased from 207 to 234 cm2/Vs while the electron concentration decreased at low temperatures. In addition, the photoluminescence peak intensity of the nearband-edge emission was increased.
7
Yamazaki, T., T. Hozuki, K. Arai, S. Toyoda, K. Koba, T. Fujiwara, and N. Yoshida. "Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria." Biogeosciences Discussions 10, no. 10 (October 25, 2013): 16615–43. http://dx.doi.org/10.5194/bgd-10-16615-2013.
Full textAbstract:
Abstract. Nitrous oxide (N2O) is a potent greenhouse gas and produced in denitrification and nitrification in environmental nitrogen cycle by various microorganism. Site preference (SP) of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathway. To determine representative SP value for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO) purified from two species of ammonia oxidizing bacteria (AOB), Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR) from Paracoccus denitrificans, respectively. The SP value for NOR reaction (−5.9 ± 2.1‰) showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰) was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2–) reduction (which is followed by NO reduction) to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for NH2OH oxidation pathway possibly due to a small contribution of NO2– reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.
8
Bennett, Sophie P., Maria J. Torres, Manuel J. Soriano-Laguna, David J. Richardson, Andrew J. Gates, and Nick E. Le Brun. "nosX is essential for whole-cell N2O reduction in Paracoccus denitrificans but not for assembly of copper centres of nitrous oxide reductase." Microbiology 166, no. 10 (October 1, 2020): 909–17. http://dx.doi.org/10.1099/mic.0.000955.
Full textAbstract:
Nitrous oxide (N2O) is a potent greenhouse gas that is produced naturally as an intermediate during the process of denitrification carried out by some soil bacteria. It is consumed by nitrous oxide reductase (N2OR), the terminal enzyme of the denitrification pathway, which catalyses a reduction reaction to generate dinitrogen. N2OR contains two important copper cofactors (CuA and CuZ centres) that are essential for activity, and in copper-limited environments, N2OR fails to function, contributing to rising levels of atmospheric N2O and a major environmental challenge. Here we report studies of nosX, one of eight genes in the nos cluster of the soil dwelling α-proteobaterium Paraccocus denitrificans. A P. denitrificans ΔnosX deletion mutant failed to reduce N2O under both copper-sufficient and copper-limited conditions, demonstrating that NosX plays an essential role in N2OR activity. N2OR isolated from nosX-deficient cells was found to be unaffected in terms of the assembly of its copper cofactors, and to be active in in vitro assays, indicating that NosX is not required for the maturation of the enzyme; in particular, it plays no part in the assembly of either of the CuA and CuZ centres. Furthermore, quantitative Reverse Transcription PCR (qRT-PCR) studies showed that NosX does not significantly affect the expression of the N2OR-encoding nosZ gene. NosX is a homologue of the FAD-binding protein ApbE from Pseudomonas stutzeri , which functions in the flavinylation of another N2OR accessory protein, NosR. Thus, it is likely that NosX is a system-specific maturation factor of NosR, and so is indirectly involved in maintaining the reaction cycle of N2OR and cellular N2O reduction.
9
Cao, Xuesong, Chenxi Zhang, Zehua Wang, and Xiaomin Sun. "Catalytic Reaction Mechanism of NO–CO on the ZrO2 (110) and (111) Surfaces." International Journal of Molecular Sciences 20, no. 24 (December 5, 2019): 6129. http://dx.doi.org/10.3390/ijms20246129.
Full textAbstract:
Due to the large population of vehicles, significant amounts of carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC) are emitted into the atmosphere, causing serious pollution to the environment. The use of catalysis prevents the exhaust from entering the atmosphere. To better understand the catalytic mechanism, it is necessary to establish a detailed chemical reaction mechanism. In this study, the adsorption behaviors of CO and NO, the reaction of NO reduction with CO on the ZrO2 (110) and (111) surfaces was performed through periodic density functional theory (DFT) calculations. The detailed mechanism for CO2 and N2 formation mainly involved two intermediates N2O complexes and NCO species. Moreover, the existence of oxygen vacancies was crucial for NO reduction reactions. From the calculated energy, it was found that the pathway involving NCO intermediate interaction occurring on the ZrO2 (110) surface was most favorable. Gas phase N2O formation and dissociation were also considered in this study. The results indicated the role of reaction intermediates NCO and N2O in catalytic reactions, which could solve the key scientific problems and disputes existing in the current experiments.
10
Takatsu, Yuta, Sharon Y. L. Lau, Li Li, and Yasuyuki Hashidoko. "Effects of Some Hill Reaction-Inhibiting Herbicides on Nitrous Oxide Emission from Nitrogen-Input Farming Soil." Applied Sciences 9, no. 9 (May 9, 2019): 1903. http://dx.doi.org/10.3390/app9091903.
Full textAbstract:
Nitrous oxide (N2O) emission-suppressing activity of some electron-transport inhibitors of the Hill reaction system was investigated. The Hill reaction inhibitors—paraquat, isouron, bromacil, diquat, and simazine—all of which have been or are currently being used as herbicides in farming activity are expected to inhibit the electron-transporting pathways of nitrate respiration in denitrifying bacteria. Using N2O-emitting soil bed (5.0 g of fresh weight) from a continuously manured Andisol corn farmland in Hokkaido, Japan, which was autoclaved and further supplemented with an active N2O-emitter, Pseudomonas sp. 5CFM15-6D, and 1 mL of 100 mM NH4NO3 or (NH4)2SO4 solution as the sole nitrogen source (final concentration, 0.2 mM) in a 30 mL gas-chromatography vial, the effects of the five herbicides on N2O emission were examined. Paraquat and isouron (each at 50 µM) showed a statistically significant suppression of N2O emission in both the nitrification and the denitrification processes after a 7-day-incubation, whereas diquat at the same concentration accelerated N2O emission in the presence of NO3−. These results suggest that paraquat and isouron inhibited both the nitrification and the denitrification processes for N2O generation, or its upstream stages, whereas diquat specifically inhibited N2O reductase, an enzyme that catalyzes the reduction of N2O to N2 gas. Incomplete denitrifiers are the key players in the potent emission of N2O from Andisol corn farmland soil because of the missing nosZ gene. The electron relay system-inhibiting herbicides—paraquat and isouron—possibly contribute to the prevention of denitrification-induced nitrogen loss from the farming soil.
Dissertations / Theses on the topic "N2O reaction gas"
1
Hunderup, James W. "An experimental investigation of the conversion of NO to NO2 in a simulated gas turbine environment." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06162009-063102/.
Full text
2
Coletta, Vitor Carlos. "Síntese e caracterização dos compostos SrTi1-xCuxO3, CuO/SrTiO3 e NiO/SrTiO3 aplicados à catálise da reação de deslocamento gás-água." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14092017-095459/.
Full textAbstract:
O titanato de estrôncio (SrTiO3) é um óxido de estrutura perovskita e tem sido intensamente estudado para uso em diversas aplicações, entre elas, como suporte catalítico. Entretanto, sua utilização especificamente na reação de deslocamento gás-água ainda é pouco explorada. Esta reação é de interesse para a produção de hidrogênio livre de CO, necessário para aplicações como o abastecimento de células de combustível. Este trabalho de tese teve como objetivo o estudo dos compostos SrTi1-xCuxO3, CuO/SrTiO3 e NiO/SrTiO3 como catalisadores para a reação de deslocamento gás-água, uma vez que, dentre os metais de baixo custo, Cu e Ni são altamente ativos para esta reação. As amostras SrTi1-xCuxO3 foram sintetizadas pelo método dos precursores poliméricos com calcinação em N2 e O2, possibilitando a obtenção de partículas de maior área superficial em comparação com a calcinação convencional em atmosfera ambiente. Para as amostras CuO/SrTiO3 e NiO/SrTiO3, o suporte SrTiO3, foi sintetizado pelo método de sol-precipitação e a impregnação com cobre e níquel foi realizada por via úmida. As técnicas de absorção e difração de raios-X in situ em condições de reação mostraram a estabilidade da estrutura e do estado de oxidação após o tratamento de redução. Imagens de microscopia eletrônica de varredura (MEV) e de transmissão (TEM) em conjunto com a espectroscopia de raios-X de energia dispersiva (EDX) foram utilizadas a fim de estabelecer uma relação entre a atividade catalítica e o teor a dispersão de fase ativa sobre o suporte. Todas as composições estudadas se mostraram ativas entre 250 e 350°C, entretanto, a composição NiO/SrTiO3 com 10% de Ni apresentou o melhor resultado, com uma conversão de CO a 350°C, próxima ao equilíbrio e estável por um período mínimo de10 h.Strontium titanate (SrTiO3) is an oxide of perovskite structure and has been extensively studied for use in several applications, including as catalytic support. However, its use specifically in the water-gas shift reaction is still little explored. This reaction is of interest for the production of CO-free hydrogen, required for applications such as in fuel cell. This work aimed to study SrTi1-xCuxO3, CuO/SrTiO3 and NiO/SrTiO3 compounds to be applied as catalysts for the water-gas shift reaction, since, among the low-cost metals, Cu and Ni are highly active for this reaction. The SrTi1-xCuxO3 samples were synthesized by the polymeric precursor method with the samples submitted to a N2 and O2 calcination, making possible to obtain particles with a larger surface area compared to conventional calcination in ambient atmosphere. For the CuO/SrTiO3 and NiO/SrTiO3 samples, the SrTiO3 support was synthesized by the sol-precipitation method and the impregnation with copper and nickel on the support was performed by a wet method. The in situ X-ray absorption and diffraction techniques under reaction conditions showed the stability of the structure and the oxidation state after the reduction treatment. Scanning electron microscopy (SEM) and transmission (TEM) images in conjunction with energy dispersive X-ray spectroscopy (EDX) were used in order to establish a relationship between the catalytic activity and the content and dispersion of the active phase on the support. All the compositions studied were active at 250 to 350 °C, however, the NiO/SrTiO3 sample with 10% of Ni presented the best result, with a CO conversion at 350 °C, close to equilibrium and stable for a minimum of 10 h.
3
Fabre, Bruno. "Synthèse et étude de films de polymères conducteurs électroniques dopés par des hétéropolyanions : application à la réduction électrocatalytique de NO2- et à la détection du NO in vivo." Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10158.
Full textAbstract:
Ce travail est consacre a la synthese, la caracterisation physico-chimique et l'application de films de polymeres conducteurs electroniques (pce) incluant des heteropolyanions (hpa). Ces entites minerales, connues pour leurs remarquables proprietes redox, sont immobilisees en tant qu'anion dopant lors de la synthese electrochimique des pce. Dans un premier temps, nous montrons qu'une electrode modifiee par un film de poly(3-methyl thiophene) dope par un hpa de structure de keggin xm#1#2o#4#0#n#- (x = p, si ; m = w, mo et n = 3, 4) presente l'electroactivite des deux partenaires. La reponse electrochimique associee a l'hpa n'est pas modifiee apres son immobilisation, pour peu que les conditions de l'electrosynthese du film soient optimisees (rapport monomere/hpa et valeur du potentiel impose). La geometrie particuliere de l'hpa n'induit pas une structure organisee dans le poly(3-methyl thiophene). Afin de remonter a une explication structurale du materiau, nous entreprenons, dans un second temps, l'etude d'un compose modele base sur un oligomere du thiophene (6t)#4#p#+/(pmo#1#2o#4#0)#p#- (6t represente l'hexamere du thiophene et 3 < p < 4). Malheureusement, la tres faible solubilite de ce sel ne permet pas des cristallisations adequates pour des etudes cristallographiques. Les films de pce/hpa peuvent realiser des electrocatalyses, a condition de choisir la bonne association. Dans ce sens, nous mettons en evidence qu'une electrode modifiee par un film de poly(n-methyl pyrrole) incluant un hpa mixte fepw#1#1o#3#9(h#2o)#4#- presente une remarquable stabilite electrochimique et activite electrocatalytique vis-a-vis de la reduction de no#2#-. Le mecanisme de reduction en phase immobilisee passe par un complexe fer-nitrosyl fepw#1#1o#3#9(no)#5#- qui assure la selectivite de cette catalyse chimique electroassistee. Cette electrode modifiee permet de la meme maniere la reduction catalytique du no dissous dans l'eau. Cette molecule, actuellement reconnue comme mediateur intercellulaire essentiel, peut etre detectee in vivo a partir d'une fibre de carbone modifiee par le depot catalytique precedent. Cette etude, realisee en collaboration avec r. Cespuglio (inserm, lyon) constitue un des rares exemples de detection fonctionnelle et en temps reel de cette molecule
4
Eliades, John Alexander. "A Radio Frequency Quadrupole Instrument for use with Accelerator Mass Spectrometry: Application to Low Kinetic Energy Reactive Isobar Suppression and Gas–phase Anion Reaction Studies." Thesis, 2012. http://hdl.handle.net/1807/32706.
Full textAbstract:
A radio frequency (rf) quadrupole instrument, currently known as an Isobar Separator for Anions (ISA), has been integrated into an Accelerator Mass Spectrometry (AMS) system to facilitate anion–gas reactions before the tandem accelerator. An AMS Cs+ sputter source provided > 15 keV ions that were decelerated in the prototype ISA to < 20 eV for reaction in a single collision cell and re-accelerated for AMS analysis. Reaction based isobar suppression capabilities were assessed for smaller AMS systems and a new technique for gas–phase reaction studies was developed.
Isobar suppression of 36S– and 12C3– for 36Cl analysis, and YF3– and ZrF3– for 90Sr analysis were studied in NO2 with deceleration to < 12 eV. Observed attenuation cross sections, σ [x 10^–15 cm^2], were σ(S– + NO2) = 6.6, σ(C3– + NO2) = 4.2, σ(YF3– + NO2) = 7.6, σ(ZrF3– + NO2) = 19. With 8 mTorr NO2, relative attenuations of S–/Cl– ~ 10^–6, C3–/Cl– ~ 10^–7, YF3–/SrF3– ~ 5 x 10^–5 and ZrF3–/SrF3– ~ 4 x 10^–6 were observed with Cl– ~ 30% and SrF3– > 90% transmission. Current isobar attenuation limits with < 1.75 MV accelerator terminal voltage and ppm impurity levels were calculated to be 36S–/Cl– ~ 4 x 10^–16, 12C3–/Cl– ~ 1.2 x 10^–16, 90YF3–/SrF3– ~ 10^–15 and 90ZrF3–/SrF3– ~ 10^–16.
Using 1.75 MV, four 36Cl reference standards in the range 4 x 10^–13 < 36Cl/Cl < 4 x 10^–11 were analyzed with 8 mTorr NO2. The measured 36Cl/Cl ratios plotted very well against the accepted values. A sample impurity content S/Cl < 6 x 10^–5 was measured and a background level of 36S–/Cl < 9 x 10^–15 was determined.
Useful currents of a wide variety of anions are produced in AMS sputter sources and molecules can be identified relatively unambiguously by stripping fragments from tandem accelerators. Reactions involving YF3–, ZrF3–, S– and SO– + NO2 in the ISA analyzed by AMS are described, and some interesting reactants are identified.
5
Ting, Yu Bin, and 余璧婷. "Theoretical Study of SO2 Formation in the Reaction of CH3S Radical with NO2，O3，O2 and HO2 in the Gas Phase." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/22119672535401874226.
Full textAbstract:
碩士國立臺灣師範大學
化學系
93
This thesis deals with the calculation of tropospheric reaction of methylthiyl radical(CH3S) with NO2，O3，O2 and HO2 to check the formation of SO2 by ab initio theory at MP2/6-311G(d) level. There are four major sections to describe the reaction mechanisms. Section 1: We study the reaction between methylthiyl radical and nitrogen dioxide(NO2) in the gas phase . The reaction proceeds with the participation of NO2 by twice or three times to produced sulfur dioxide. The formation energy is relatively large and the product is stable. Therefore, we think the reaction of methylthiyl radical with nitrogen dioxide to produce sulfur dioxide is very possible. Section 2: We studied the reaction of CH3S with O3.We found out that with the participation of O3 two times it is possible to form CH3SO2 and than dissociated to SO2.We detect the reaction of methylthiyl radical with ozone twice to produce CH3SO2.After that, we through the thermal decomposition of CH3SO2 and we can get SO2. Section 3: We studied the reaction of CH3S+O2. We found out that the cleavage energy of O-O bond of intermediate is quite high. As a consequence, it is not possible for the formation of SO2 via this process. Section 4: We studied the reaction of CH3S+HO2.We found out that the intermediates D2 and D5 are very stable, and it seems not possible to proceed further to produce SO2 in this reaction.
Books on the topic "N2O reaction gas"
1
Reychler, Luc. Peacemaking, Peacekeeping, and Peacebuilding. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190846626.013.274.
Full textAbstract:
Peacemaking, peacekeeping, and peacebuilding have generated considerable interest in the areas of education, research, and politics. This can be attributed in part to the growing recognition that there are limits to violence and that proactive violence prevention is more cost-effective than reactive conflict prevention. Peacebuilding became part of the official discourse when the United Nations Secretary-General Boutros Boutros-Ghali introduced the concept of post-conflict peacebuilding in the Agenda for Peace. The agenda specified four areas of action relating to preventive diplomacy, peacemaking, peacekeeping, and peacebuilding. Two important documents have helped bring peacebuilding to the mainstream: the 2000 Brahimi Report, a response to the failures of complex UN peacekeeping in the 1990s, and In Larger Freedom: Towards Development, Security and Human Rights, which led to the establishment of the Peacebuilding Commission. Conflict prevention and peacebuilding have also been mainstreamed in the European Union and in most of the foreign offices of the member states. A central focus of studies on peacebuilding is the interrelationships between peacemaking, political change, development, peacekeeping, and reconciliation. Despite the progress made in terms of research, there are a number of gaps and challenges that still need to be addressed. Many analysts, for example, leave the end state vague and implicit and make no systematic differentiation between different types of peace. With respect to context, two salient issues require more attention: the qualities of a peacebuilder and the role of integrative power. The widest research gap is found in the planning of the peacebuilding process.
2
Crease, Robert P., and Peter D. Bond. The Leak. The MIT Press, 2022. http://dx.doi.org/10.7551/mitpress/14577.001.0001.
Full textAbstract:
How the discovery of a harmless leak of radiation sparked a media firestorm, political grandstanding, and fearmongering that closed a vital scientific facility. In 1997, scientists at Brookhaven National Laboratory found a small leak of radioactive water near their research reactor. Brookhaven was—and is—a world-class, Nobel Prize–winning lab, and its reactor was the cornerstone of US materials science and one of the world's finest research facilities. The leak, harmless to health, came from a storage pool rather than the reactor. But its discovery triggered a media and political firestorm that resulted in the reactor's shutdown, and even attempts to close the entire laboratory. A quarter century later, the episode reveals the dynamics of today's controversies in which fears and the dismissal of science disrupt serious discussion and research of vital issues such as vaccines, climate change, and toxic chemicals. This story has all the elements of a thriller, with vivid characters and dramatic twists and turns. Key players include congressmen and scientists; journalists and university presidents; actors, supermodels, and anti-nuclear activists, all interacting and teaming up in surprising ways. The authors, each with insider knowledge of and access to confidential documents and the key players, reveal how a fact of no health significance could be portrayed as a Chernobyl-like disaster. This compelling exposé reveals the gaps between scientists, politicians, media, and the public that have only gotten more dangerous since 1997.
3
Esteva, Gustavo. What is Development? Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190846626.013.360.
Full textAbstract:
Development was born as aid, an expression of the modern obsession with “caring” used by disabling professions and the service industry. However, by 1980, it was already clear that there was no correlation between aid and economic growth, and that aid was an obstacle for social transformation. Development was also born in the context of the Cold War. For President Truman, the American way of life was a democratic and egalitarian ideal to overcome the communist “threat” by closing the gap between industrial and “underdeveloped” countries. In addition, development was a reaction to the initiatives of the colonized world, increasingly challenging Western domination. Since Truman, development has connoted at least one thing: to escape from the vague, indefinable, and undignified condition known as underdevelopment. However, the Age of Development—the historical period formally inaugurated in 1949—is now coming to an end. The future of development studies lies in archaeology, to explore the ruins it left behind by looking at development’s pre-history and conceptual history, as well as the development enterprise. Since the 1970s, new campaigns were launched to focus the effort in getting for the underdeveloped, at least, the fulfillment of their “basic needs.” Meanwhile, the “law of scarcity” was construed by the economists to denote the technical assumption that man’s wants are huge and infinite, whereas his means are limited though improvable. Poverty and development thus go hand in hand. Indeed, historical experience reveals that development generates poverty. By 1985, the idea of post-development has already emerged.
Book chapters on the topic "N2O reaction gas"
1
Miller, J. A., and P. Glarborg. "Modelling the Formation of N2O and NO2 in the Thermal De-NOx Process." In Gas Phase Chemical Reaction Systems, 318–33. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-80299-7_25.
Full text
2
ter Horst, M., K. S. Bradley, and G. C. Schatz. "Mode-Specific Chemistry in the H + HCN and H + N2O Reactions." In Gas Phase Chemical Reaction Systems, 144–54. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-80299-7_10.
Full text
3
Torchin, L., P. Prigent, and H. Brunet. "The C + N2O → CN(A,X) + NO Reaction: a Possible Candidate for a Near Infrared Electronic Transition Chemical Laser?" In Gas Flow and Chemical Lasers, 535–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-71859-5_75.
Full text
4
Zaman, M., K. Kleineidam, L. Bakken, J. Berendt, C. Bracken, K. Butterbach-Bahl, Z. Cai, et al. "Automated Laboratory and Field Techniques to Determine Greenhouse Gas Emissions." In Measuring Emission of Agricultural Greenhouse Gases and Developing Mitigation Options using Nuclear and Related Techniques, 109–39. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-55396-8_3.
Full textAbstract:
AbstractMethods and techniques are described for automated measurements of greenhouse gases (GHGs) in both the laboratory and the field. Robotic systems are currently available to measure the entire range of gases evolved from soils including dinitrogen (N2). These systems usually work on an exchange of the atmospheric N2with helium (He) so that N2 fluxes can be determined. Laboratory systems are often used in microbiology to determine kinetic response reactions via the dynamics of all gaseous N species such as nitric oxide (NO), nitrous oxide (N2O), and N2. Latest He incubation techniques also take plants into account, in order to study the effect of plant–soil interactions on GHGsand N2 production. The advantage of automated in-field techniques is that GHG emission rates can be determined at a high temporal resolution. This allows, for instance, to determine diurnal response reactions (e.g. with temperature) and GHG dynamics over longer time periods.
5
Kiesse Zeleme, Ana, and António André Chivanga Barros. "Biodiesel Production Using Reactive Distillation Column Based on Intensification Processes." In Soybean - Recent Advances in Research and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101928.
Full textAbstract:
Environment concerns related to the use of fossil fuels are reflected in proposals for new conversion technologies to produce biofuels from biomass. The biofuels produced in this context have the same characteristics as petroleum derivatives, however, with reduced greenhouse gas emissions and with no sulfur in their molecular structures. In this context, a reactive distillation (RD) column was designed, constructed, installed, and operated using process intensification principles. It was applied in the production of biodiesel, using residual frying oil as the raw material, by the transesterification reaction, in a continuous regime. The process started with alcohol in excess in the reboiler, located in the bottom of the RD, which was heated through the combustion gas of liquefied petroleum gas (LPG) to produce ethanol vapor, which was recirculated in the column until stabilization. In this stage, the reagents were inserted into the feed tanks. Thus, the tank valves were opened for each reactant. The reaction products were recovered during the experiment from the bottom of the column and they were distilled to obtain two phases, biodiesel and glycerol. The results obtained from this study show that the use of an RD column can produce biodiesel in a continuou regime.
6
Atkins, Peter. "Irritating Atmospheres: Atmospheric Photochemistry." In Reactions. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199695126.003.0030.
Full textAbstract:
The problem of photochemically generated smog begins inside internal combustion engines, where at the high temperatures within the combustion cylinders and the hot exhaust manifold nitrogen molecules and oxygen molecule combine to form nitric oxide, NO. Almost as soon as it is formed, and when the exhaust gases mingle with the atmosphere, some NO is oxidized to the pungent and chemically pugnacious brown gas nitrogen dioxide, NO2, 1. We need to watch what happens when one of these NO2 molecules is exposed to the energetic ultraviolet photons in sunlight. We see a photon strike the molecule and cause a convulsive tremor of its electron cloud. In the brief instant that the electron cloud has swarmed away from one of the bonding regions, an O atom makes its escape, leaving behind an NO molecule. We now continue to watch the liberated O atom. We see it collide with an oxygen molecule, O2, and stick to it to form ozone, O3, 2. This ozone is formed near ground level and is an irritant; ozone at stratospheric levels is a benign ultraviolet shield. Now keep your eye on the ozone molecule. In one instance we see it collide with an NO molecule, which plucks off one of ozone’s O atoms, forming NO2 and letting O3 revert to O2. Another fate awaiting NO2 is for it to react with oxygen and any unburned hydrocarbon fuel and its fragments that have escaped into the atmosphere. We can watch that happening too where the air includes surviving fragments of hydrocarbon fuel molecules. A lot of little steps are involved, and they occur at a wide range of rates. Let’s suppose that some unburned fuel escapes as ethane molecules, CH3CH3, 3. Although ethane is not present in gasoline, a CH3CH2· radical (Reaction 12) would have been formed in its combustion and then combined with an H atom in the tumult of reactions going on there. You already know that vicious little O atoms are lurking in the sunlit NO2-ridden air. We catch sight of one of their venomous acts: in a collision with an H2O molecule they extract an H atom, so forming two ·OH radicals.
7
Martinho Simões, José A., and Manuel Minas da Piedade. "Gas-Phase Ion Energetics." In Molecular Energetics. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195133196.003.0007.
Full textAbstract:
The experimental methods designed to investigate the energetics of gas-phase ions have been another important source of thermochemical data, particularly throughout the past two or three decades. In this chapter, we discuss the main quantities that are measured experimentally and lead to reaction enthalpy values. The adiabatic ionization energy of any molecule AB (mono-, di-, or polyatomic), represented by Ei (AB), is the minimum energy required to remove an electron from the isolated molecule at 0 K: AB(g) → AB+(g) + e−(g) (4.1) The proviso T = 0 signifies that AB is in its electronic, vibrational, and rotational ground states and has no translational energy. The word isolated indicates the perfect gas model. The “minimum energy” condition ensures that AB+ is also in its electronic, vibrational, and rotational ground states and the translational energies of AB+ and e− are both zero; it also indicates that the products in reaction 4.1 do not interact, that is, they also conform with the perfect gas model.
8
Calvert, Jack G., John J. Orlando, William R. Stockwell, and Timothy J. Wallington. "The Oxides of Nitrogen: Their Relation to Tropospheric Ozone." In The Mechanisms of Reactions Influencing Atmospheric Ozone. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190233020.003.0006.
Full textAbstract:
Reactive (or “odd”) nitrogen is emitted into the atmosphere in a variety of forms, with the most important being NOx (NO and NO2), ammonia (NH3), and nitrous oxide (N2O). Emissions of these species into the atmosphere have been summarized, for example, by the IPCC Fourth Assessment Report (the AR4; IPCC, 2007). Some discussion of NOx emissions and trends has also been presented in Chapter I. Emissions of NOx are mainly the result of anthropogenic activity associated with fossil fuel combustion and industrial activity. For the 1990s, the AR4 estimates total anthropogenic NOx emissions of 33.4 TgN yr−1, with natural emissions (mostly from soil and lightning) accounting for an additional 8.4–13.7 TgN yr−1. Ammonia emissions are comparable in magnitude to those for NOx, with anthropogenic emissions (45.5 TgN yr−1) again exceeding natural emissions (10.6 TgN yr−1). Although the majority of the ammonia produces aerosols or is scavenged by aerosol and is subsequently lost from the atmosphere, some gas phase oxidation does occur, which can in part lead to NOx production. The N2O source strength is about 17.7 TgN yr−1, with natural sources outweighing anthropogenic ones (IPCC, 2007). However, N2O is essentially inert in the troposphere, and thus the vast majority of its photooxidation and concomitant NOx release occurs in the stratosphere. The major NOx − related reactions occurring in the Earth’s troposphere are summarized in Figure III-A-1. As just alluded to, the species NO and NO2 are jointly referred to as NOx and are often treated collectively. This is because, under daytime conditions, these two species are rapidly interconverted, with the interconversion occurring on a much shorter timescale than the loss of either species.
9
Keefer, Robert F. "Fertilizers." In Handbook of Soils for Landscape Architects. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195121025.003.0017.
Full textAbstract:
Fertilizers for soil on which plants grow come in a variety of forms, such as organic, inorganic, single nutrient, double nutrient, complete fertilizer (contains N, P, and K in that order), speciality fertilizers, composts, and manures. Information about each of these forms follows. Most of the N used in fertilizers is derived from a synthetic process developed by Europeans called the “Claude-Haber process.” This process uses nitrogen gas (N2) from the atmosphere along with hydrogen gas (H2) from natural gas in a device where pressure can be increased and temperature can be raised. The reaction is accelerated using an iron catalyst and removing the product (NH3) as it is formed. The Fe catalyst is subject to poisoning from impurities, such as As, Co, P, or S. Anhydrous ammonia has the highest percentage of N and the cheapest per unit of N since no processing is involved. Anhydrous (without water) ammonia is a gas but when compressed changes to a liquid. For application to soils a pressurized tank is required with a device to inject the liquid ammonia into the soil. Upon release of pressure, the liquid changes back to a gas; however, the ammonia gas reacts with the moisture in the soil to form NH4+ that is available for plants. One problem with ammonia is that NH3 gas is toxic to seedlings and growing plants, so must be applied prior to planting. This limits its use for landscape projects. Salt solutions of aqua ammonia are obtained by dissolving ammonia gas, ammonium nitrate, or urea in water. The amount dissolved will vary the concentration of N in the final product. This can be used in landscape projects, but care must be used as this material can salt out and plug up orifices when sprayed onto a soil. There is no real difference between liquid or solid fertilizers, provided the percentage of N is the same. Ammonia Nitrate [NH4NO3] (33.5% N) Ammonium nitrate is formed by ammonia gas reacting with nitric acid: . . . NH3 + HNO3 → NH4NO3 . . . This material is hygroscopic (absorbs water from the air) and requires moisture-proof bags for storage.
10
Sposito, Garrison. "Oxidation– Reduction Reactions." In The Chemistry of Soils. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780190630881.003.0010.
Full textAbstract:
Soils become flooded occasionally by intense rainfall or by runoff, and a significant portion of soils globally underlies highly productive wetlands ecosystems that are inundated intermittently or permanently. Peat-producing wetlands (bogs and fens) account for about half the inundated soils, with swamps and rice fields each accounting for about one-sixth. Wetlands soils hold about one-third of the total nonfossil fuel organic C stored below the land surface, which is about the same amount of C as found in the atmosphere or in the terrestrial biosphere. This C storage is all the more impressive given that wetlands cover less than 6% of the global land area. On the other hand, wetlands ecosystems are also significant locales for greenhouse gas production. They constitute the largest single source of CH4 entering the atmosphere, emitting about one-third the global total, with half this amount plus more than half the global N2O emissions coming from just three rice-producing countries. A soil inundated by water cannot exchange O2 readily with the atmosphere. Therefore, consumption of O2 and the accumulation of CO2 ensue as a result of soil respiration. If sufficient humus metabolized readily by the soil microbiome (“labile humus”) is available, O2 disappearance after inundation is followed by a characteristic sequence of additional chemical transformations. This sequence is illustrated in Fig. 6.1 for two agricultural soils: a German Inceptisol under cereal cultivation and a Philippines Vertisol under paddy rice cultivation. In the German soil, which was always well aerated prior to its sudden inundation, NO3- is observed to disappear from the soil solution, after which soluble Mn(II) and Fe(II) begin to appear, whereas soluble SO42- is depleted (left side of Fig. 6.1). The appearance of the two soluble metals results from the dissolution of oxyhydroxide minerals (Section 2.4). Despite no previous history of inundation, CH4 accumulation in the soil occurs and increases rapidly after SO42- becomes undetectable and soluble Mn(II) and Fe(II) levels have become stabilized. During the incubation time of about 40 days, the pH value in the soil solution increased from 6.3 to 7.5, whereas acetic acid (Section 3.1) as well as H2 gas were produced.
Conference papers on the topic "N2O reaction gas"
1
Smith, Michael A., Christopher D. Depcik, Stefan Klinkert, John W. Hoard, Stanislav V. Bohac, and Dionissios N. Assanis. "NO2 Reaction Pathways With NH3 on an Fe-Zeolite SCR Catalyst." In ASME 2011 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/icef2011-60114.
Full textAbstract:
One approach for nitrogen oxides (NOx) emission control of medium duty diesel engines is through the use of a combination Lean NOx Trap and Selective Catalytic Reduction (LNT-SCR) catalyst system. In this system, part of the NOx conversion occurs via an NH3 SCR catalyst that is dependent on the NO2 to NOx ratio of the feed gas with NO2 being a more advantageous oxidizer. One benefit of using this system is the conversion of NO to NO2 over the LNT which increases the NO2:NOx ratio of the feed gas to the SCR catalyst. An experimental study has been performed to investigate the NO2-NH3 reaction for an Fe-based zeolite SCR catalyst using a bench top flow reactor. The increase in NO2 concentration at the inlet of the SCR results in the formation of large quantities of N2O from 200°C to 400°C. Further experiments determined that N2O and NH3 react above 350°C. This has led to a hypothesis that one primary SCR reaction (Slow SCR) can be replaced with two reaction steps featuring NH3, NO2, and N2O. As a result, this paper proposes five NOx reduction reactions as part of a global mechanism, which would account for the observed experimental behavior.
2
NAHMAD, ALI ZADEH, NAGIEV TOFIK, and NAGIEVA INARA. "Green oxidants H2O2 and N2O in reaction of coherent-synchronized gas phase oxidation of pyridine." In Fifth International Conference on Advances in Bio-Informatics, Bio-Technology and Environmental Engineering - ABBE 2017. Institute of Research Engineers and Doctors, 2017. http://dx.doi.org/10.15224/978-1-63248-130-6-07.
Full text
3
Okumura, Yukihiko, Hirotatsu Watanabe, and Ken Okazaki. "Effects of Heterogeneous Reaction and Slow/Rapid Volatilization Process on N2O Formation During the Combustion of Pulverized Biomass." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44436.
Full textAbstract:
The purpose of this study is to clarify the fundamental and general features of N2O formation during the combustion of pulverized biomass under low temperature. First, the effect of various important factors, i.e., volatilization process (i.e., either slow or rapid dispersion), oxygen concentration, and solid-gas reaction on N2O formation were investigated by theoretical analysis. The analysis of the effect of the slow/rapid volatilization process on the formation of nitrous oxide showed that the conversion ratio of biomass-N to N2O increases with the decrease in the dispersion of volatile matter per unit time; it means that biomass-N is effectively converted to N2O during slow volatilization. The analysis of the effect of initial oxygen concentration on the formation of nitrous oxide showed that at low temperature (T = 1100K), the level of N2O emission increases, while that of NO emission decreases, with the decrease in initial oxygen concentration. In other words, there is a trade-off relationship between the formation of NO and that of N2O. With respect to the effect of solid-gas reaction, the gasification reactions between CO2, O2, and C(s) occur simultaneously on the surface of biomass particles during combustion. Further, the N2O emission level increases with the increase in N-content of the biomass, while the NO emission level remains constant during low-temperature combustion.
4
Steele, Robert C., Jon H. Tonouchi, David G. Nicol, David C. Horning, Philip C. Malte, and David T. Pratt. "Characterization of NOx, N2O, and CO for Lean-Premixed Combustion in a High-Pressure Jet-Stirred Reactor." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-128.
Full textAbstract:
A high-pressure jet-stirred reactor (HP-JSR) has been built and applied to the study of NOx and N2O formation and CO oxidation in lean-premixed (LPM) combustion. The measurements obtained with the HP-JSR provide information on how NOx forms in lean-premixed, high-intensity combustion, and provide comparison to NOx data published recently for practical LPM combustors. The HP-JSR results indicate that the NOx yield is significantly influenced by the rate of relaxation of super-equilibrium concentrations of the O-atom. Also indicated by the HP-JSR results are characteristic NOx formation rates. Two computational models are used to simulate the HP-JSR, and to provide comparison to the measurements. The first is a chemical reactor model (CRM) consisting of two perfectly-stirred reactors (PSRs) placed in series. The second is a stirred reactor model with finite rate macromixing (i.e., recirculation) and micromixing. The micromixing is treated by either coalescence-dispersion (CD) or interaction-by-exchange-with-the-mean (IEM) theory. Additionally, a model based on one-dimensional gas dynamics with chemical reaction is used to assess chemical conversions within the gas sample probe.
5
Yang, Huateng, S. R. Krishnan, K. K. Srinivasan, and K. Clark Midkiff. "Sensitivity Analyses of NOx Formation in Micro-Pilot Ignited Natural Gas Engines." In ASME 2004 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/icef2004-0851.
Full textAbstract:
A sensitivity analysis of NOx formation in micro-pilot ignited natural gas dual fuel engines is performed based on a phenomenological combustion model. The model’s NOx formation mechanism incorporates a super-extended Zel’dovich mechanism (up to 43 reactions). The sensitivity analysis compares the contribution of each major reaction to NOx formation, and identifies the rate controlling NOx formation reactions. The formation rates for reactions involving NOx are also investigated to reveal the primary NOx formation paths. Results show that there are two main NOx formation paths both in the packets zone and the burned zone. The rate limiting reactions for the packets zone are identified as: O+N2=NO+NN2+HO2=NO+HNO Rate limiting reactions for the burned zone are: N2O+M=N2+O+MN2+HO2=NO+HNO Since the aforementioned reaction significantly influence the net NOx prediction, it is important that the corresponding reaction rates be determined fairly accurately. Finally, because the quasi-steady-state assumption is commonly used for certain species in NOx modeling, a transient relative error is estimated to evaluate its use. The relative error in NOx prediction with and without this assumption is of the order of 2 percent. Clearly, sensitivity analysis can provide valuable insight into understanding the possible NOx formation pathways in engines and improve the status of current prediction tools to obtain better estimates.
6
Colorado, Andrés, and Vincent McDonell. "Reactor Network Analysis to Assess Fuel Composition Effects on NOx Emissions From a Recuperated Gas Turbine." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26361.
Full textAbstract:
This paper addresses the numerical prediction of NOx emissions from a micro turbine generator (MTG) using a chemical reactor network (CRN). In particular, the effect of fuel composition on NOx formation is analyzed. The numerical predictions are compared with available experimental results. The results obtained with the reactor network analysis (RNA) for the mixtures with heavier alkanes are in good agreement with the experimental results; however the methodology indicates that the prediction is sensitive to the selection of the reaction mechanism. Also, it was possible to predict measured trends for the effect of the dilution with CO2, but the slope of the trend differs from the experiments. The analysis of the results indicates that most of the NOx measured at the turbine exit for the conditions of this study is formed through the N2O route. This is the dominant pathway for this system, regardless of the fuel composition or the reaction mechanism used.
7
Eggels, R. L. G. M. "Modelling of NOx Formation of a Premixed DLE Gas Turbine Combustor." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0069.
Full textAbstract:
To comply with the stringent emission regulations industrial gas turbines operate under lean premixed conditions. To be able to predict emissions in an early design phase, advanced premixed combustion models are required. The rate of NOx formation is sensitive to temperature and some radical concentrations, therefore the flame predictions have to be accurate and detailed. It is well known that there are several routes (thermal, prompt, N2O mechanism) by which NOx can be formed. As lean premixed gas turbines operate at relative low flame temperatures, the contribution of the prompt NO and N2O mechanisms has to be accounted for. The modelling of NOx formation is done in a post-processor, as the influence of nitrogen species on the main combustion characteristics is negligible. This post-processor is based on flame calculations using a Flame Generated Manifold method. This is a reduced reaction mechanism, so that only a limited number of variables have to be solved during the CFD computations. A post-processor method has been developed to compute NO formation. Differential equations are solved for NO and N2O, other species including nitrogen are solved using a steady-state equation. The flame and post-processor models are applied to 2-D and 3-D models of an industrial series staged gas turbine. Parameter studies for the fuel split between the two stages and inlet fuel/air ratio variations have been carried out and the data has been compared with generic engine data.
8
Pundle, Anamol, David G. Nicol, Philip C. Malte, and Joel D. Hiltner. "Modeling the Formation of Pollutant Emissions in Large-Bore, Lean-Burn Gas Engines." In ASME 2017 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icef2017-3577.
Full textAbstract:
This paper discusses chemical kinetic modeling used to analyze the formation of pollutant emissions in large-bore, lean-burn gas reciprocating engines. Pollutants considered are NOx, CO, HCHO, and UHC. A quasi-dimensional model, built as a chemical reactor network (CRN), is described. In this model, the flame front is treated as a perfectly stirred reactor (PSR) followed by a plug flow reactor (PFR), and reaction in the burnt gas is modeled assuming a batch reactor of constant-pressure and fixed-mass for each crank angle increment. The model treats full chemical kinetics. Engine heat loss is treated by incorporating the Woschni model into the CRN. The mass burn rate is selected so that the modeled cylinder pressure matches the experiment pressure trace. Originally, the model was developed for large, low speed, two-stoke, lean-burn engines. However, recently, the model has been formatted for the four-stroke, open-chamber, lean-burn engine. The focus of this paper is the application of the model to a four-stroke engine. This is a single-cylinder non-production variant of a heavy duty lean-burn engine of about 5 liters cylinder displacement Engine speed is 1500 RPM. Key findings of this work are the following. 1) Modeled NOx and CO are found to agree closely with emission measurements for this engine over a range of relative air-fuel ratios tested. 2) This modeling shows the importance of including N2O chemistry in the NOx calculation. For λ = 1.7, the model indicates that about 30% of the NOx emitted is formed by the N2O mechanism, with the balance from the Zeldovich mechanism. 3) The modeling shows that the CO and HCHO emissions arise from partial oxidation late in the expansion stroke as unburned charge remaining mixes into the burnt gas. 4) Model generated plots of HCHO versus CH4 emission for the four-stroke engine are in agreement with field data for large-bore, lean-burn, gas reciprocating engines. Also, recent engine tests show the correlation of UHC and CO emissions to crevice volume. These tests suggest that HCHO emissions also are affected by crevice flows through partial oxidation of UHC late in the expansion stroke.
9
Tong, Timothy W., Mohsen M. Abou-Ellail, Yuan Li, and Karam R. Beshay. "Numerical Prediction of Nitrogen Oxides in Radiant Porous Burner Flows." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32064.
Full textAbstract:
The present paper is concerned with the numerical computation of flow, heat transfer and chemical reactions in porous burners. The porous solid matrix acts as a host for redistributing the thermal energy transferred to it from the hot reacting gases. Inside the porous matrix, heat is transferred down stream by conduction and radiation. This thermal energy is then transferred to the incoming cold fuel/air mixture to initiate the chemical reaction processes and thus stabilize the flame. One of the important features of porous burners is its presumed low levels of NO concentration. In the present work, the computed NOx is compared with experimental data and open premixed flames. In order to accurately compute the nitric oxide levels in porous burners, both prompt and thermal NOx mechanisms are included. In the present work, the porous burner species mass fraction source terms are computed from an ‘extended’ reaction mechanism, controlled by chemical kinetics of elementary reactions. The porous burner has mingled zones of porous/nonporous reacting flow, i.e., the porosity is not uniform over the entire domain. Finite-volume equations are obtained by formal integration over control volumes surrounding each grid node. Up-wind differencing is used to insure that the influence coefficients are always positive. Finite-difference equations are solved, iteratively, for velocity components, pressure correction, gas enthalpy, species mass fractions and solid matrix temperature. A non-uniform (80×80) computational grid is used. The grid used to solve the solid energy equation is extended inside the solid annular wall of the porous burner, to improve its modeling. A discrete-ordinate model with S4 quadrature is used for the computation of thermal radiation emitted from the solid matrix. The porous burner uses a premixed CH4-air mixture, while its radiating characteristics are required to be studied numerically under equivalence ratios 0.6 and 0.5. Twenty-five species are included, involving 75 elementary chemical reactions. The computed solid wall temperature profiles are compared with experimental data for similar porous burners. The obtained agreement is fairly good. Some reacting species, such as H2O, CO2, H2, NO and N2O increase steadily inside the reaction zone. However, unstable products, such as HO2, H2O2 and CH3, increase in the preheating zone to be depleted afterward.
10
Stiehl, Bernhard, Marcel Otto, Malcolm Newmyer, Max Fortin, Tommy Genova, Kareem Ahmed, Jayanta Kapat, Stefano Orsino, and Carlo Arguinzoni. "Numerical Study of Three Gaseous Fuels on the Reactor Length and Pollutant Formation Under Lean Gas Turbine Conditions." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-83343.
Full textAbstract:
Abstract The present paper numerically studies the impact of three gaseous fuels on the reaction characteristics and pollutant formation in a lean combustion system. The models include an equilibrium calculation with Ansys-Chemkin-Pro, as well as a 3D half-width CFD model using Large Eddy Simulation (LES) and Adaptive Mesh Refinement (AMR) models. The outcomes are targeted to benefit the transition to carbon-free operation of aviation turbines. Three fuels, methane (CH4), hydrogen (H2), and ammonia (NH3) as well as blends thereof were compared at constant equivalence ratios to obtain a firing temperature level of T = 1800°C. The kinetic mechanism in use was suggested and validated by Okafor et al., including 42 species to describe CH4/H2/NH3-air combustion and NOx chemistry. The formation of nitrogen oxide pollutants (NO, NO2 and N2O) were analyzed to determine the sensitivity to the three fuels and their blends. Secondly, a fuel injector scaling study was performed, and a significantly larger jet diameter was selected to compensate for the increased stoichiometric mixture fraction and reduced blend density relative to CH4-fueled architecture. Lastly, the three-dimensional AMR-LES model provided validation of the injector re-sizing, as well as further insight into the expected fuel-air distribution by convective mixing. While the substitution of methane-fueled gas turbines with carbon-free alternatives is generally feasible, blending of H2 and NH3 fuels could be a promising strategy to utilize existing turbine combustors, while retaining reaction timescales close to those of CH4-powered systems.
Reports on the topic "N2O reaction gas"
1
Laine, R. M. Low temperature, sulfur tolerant homogeneous catalysts for the water-gas shift reaction. Task 1, Topical report No. 1. Office of Scientific and Technical Information (OSTI), January 1986. http://dx.doi.org/10.2172/10162285.
Full text
2
Locy, Robert D., Hillel Fromm, Joe H. Cherry, and Narendra K. Singh. Regulation of Arabidopsis Glutamate Decarboxylase in Response to Heat Stress: Modulation of Enzyme Activity and Gene Expression. United States Department of Agriculture, January 2001. http://dx.doi.org/10.32747/2001.7575288.bard.
Full textAbstract:
Most plants accumulate the nonprotein amino acid, g-aminobutyric acid (GABA), in response to heat stress. GABA is made from glutamate in a reaction catalyzed by glutamate decarboxylase (GAD), an enzyme that has been shown by the Israeli PI to be a calmodulin (CaM) binding protein whose activity is regulated in vitro by calcium and CaM. In Arabidopsis there are at least 5 GAD genes, two isoforms of GAD, GAD1 and GAD2, are known to be expressed, both of which appear to be calmodulin-binding proteins. The role of GABA accumulation in stress tolerance remains unclear, and thus the objectives of the proposed work are intended to clarify the possible roles of GABA in stress tolerance by studying the factors which regulate the activity of GAD in vivo. Our intent was to demonstrate the factors that mediate the expression of GAD activity by analyzing the promoters of the GAD1 and GAD2 genes, to determine the role of stress induced calcium signaling in the regulation of GAD activity, to investigate the role of phosphorylation of the CaM-binding domain in the regulation of GAD activity, and to investigate whether ABA signaling could be involved in GAD regulation via the following set of original Project Objectives: 1. Construction of chimeric GAD1 and GAD2 promoter/reporter gene fusions and their utilization for determining cell-specific expression of GAD genes in Arabidopsis. 2. Utilizing transgenic plants harboring chimeric GAD1 promoter-luciferase constructs for isolating mutants in genes controlling GAD1 gene activation in response to heat shock. 3. Assess the role of Ca2+/CaM in the regulation of GAD activity in vivo in Arabidopsis. 4. Study the possible phosphorylation of GAD as a means of regulation of GAD activity. 5. Utilize ABA mutants of Arabidopsis to assess the involvement of this phytohormone in GAD activation by stress stimuli. The major conclusions of Objective 1 was that GAD1 was strongly expressed in the elongating region of the root, while GAD2 was mainly expressed along the phloem in both roots and shoots. In addition, GAD activity was found not to be transcriptionally regulated in response to heat stress. Subsequently, The Israeli side obtained a GAD1 knockout mutation, and in light of the objective 1 results it was determined that characterization of this knockout mutation would contribute more to the project than the proposed Objective 2. The major conclusion of Objective 3 is that heat-stress-induced changes in GAD activity can be explained by heat-stress-induced changes in cytosolic calcium levels. No evidence that GAD activity was transcriptionally or translationally regulated or that protein phosphorylation was involved in GAD regulation (objective 4) was obtained. Previously published data by others showing that in wheat roots ABA regulated GABA accumulation proved not to be the case in Arabidopsis (Objective 5). Consequently, we put the remaining effort in the project into the selection of mutants related to temperature adaptation and GABA utilization and attempting to characterize events resulting from GABA accumulation. A set of 3 heat sensitive mutants that appear to have GABA related mutations have been isolated and partially characterized, and a study linking GABA accumulation to growth stimulation and altered nitrate assimilation were conducted. By providing a better understanding of how GAD activity was and was not regulated in vivo, we have ruled out the use of certain genes for genetically engineering thermotolerance, and suggested other areas of endeavor related to the thrust of the project that may be more likely approaches to genetically engineering thermotolerance.
3
Sirkar, K. K., S. Majumdar, and S. Bhaumik. Rapid pressure swing absorption cleanup of post-shift reactor synthesis gas. Technical progress report No. 4, June 1, 1991--September 31, 1991. Office of Scientific and Technical Information (OSTI), October 1991. http://dx.doi.org/10.2172/10109990.
Full text
4
Hochman, Ayala, Thomas Nash III, and Pamela Padgett. Physiological and Biochemical Characterization of the Effects of Oxidant Air Pollutants, Ozone and Gas-phase Nitric Acid, on Plants and Lichens for their Use as Early Warning Biomonitors of these Air Pollutants. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7697115.bard.
Full textAbstract:
Introduction. Ozone and related oxidants are regarded as the most important phytotoxic air pollutant in many parts of the western world. A previously unrecognized component of smog, nitric acid, may have even greater deleterious effects on plants either by itself or by augmenting ozone injury. The effects of ozone on plants are well characterized with respect to structural and physiological changes, but very little is known about the biochemical changes in plants and lichens exposed to ozone and/or HNO3. Objectives.To compare and contrast the responses of crop plants and lichens to dry deposition of HNO3 and O3., separately, and combined in order to assess our working hypothesis that lichens respond to air pollution faster than plants. Lichens are most suitable for use as biomonitors because they offer a live-organism-based system that does not require maintenance and can be attached to any site, without the need for man-made technical support systems. Original Immediate aims To expose the tobacco (Nicotiana tabacum L.) cultivar Bel-W3 that is ozone supersensitive and the ozone sensitive red kidney bean (Phaseolusvulgaris) and the lichen Ramalinamenziesii to controlled HNO3 and O3 fumigations and combined and to follow the resulting structural, physiological and biochemical changes, with special reference to reactive oxygen species related parameters. Revised. Due to technical problems and time limitations we studied the lichen Ramalinamenziesii and two cultivar of tobacco: Bel-W3 that is ozone supersensitive and a resistant cultivar, which were exposed to HNO3 and O3 alone (not combined). Methodology. Plants and lichens were exposed in fumigation experiments to HNO3 and O3, in constantly stirred tank reactors and the resulting structural, physiological and biochemical changes were analyzed. Results. Lichens. Exposure of Ramalinamenziesiito HNO3 resulted in cell membrane damage that was evident by 14 days and continues to worsen by 28 days. Chlorophyll, photosynthesis and respiration all declined significantly in HNO3 treatments, with the toxic effects increasing with dosage. In contrast, O3 fumigations of R. menziesii showed no significant negative effects with no differences in the above response variables between high, moderate and low levels of fumigations. There was a gradual decrease in catalase activity with increased levels of HNO3. The activity of glutathione reductase dropped to 20% in thalli exposed to low HNO3 but increased with its increase. Glucose 6-phosphate dehydrogenase activity increase by 20% with low levels of the pollutants but decreased with its increase. Tobacco. After 3 weeks of exposure of the sensitive tobacco cultivar to ozone there were visible symptoms of toxicity, but no danmage was evident in the tolerant cultivar. Neither cultivar showed any visible symptoms after exposure to HNO3.In tobacco fumigated with O3, there was a significant decrease in maximum photosynthetic CO2 assimilation and stomatal conductance at high levels of the pollutant, while changes in mesophyll conductance were not significant. However, under HNO3 fumigation there was a significant increase in mesophyll conductance at low and high HNO3 levels while changes in maximum photosynthetic CO2 assimilation and stomatal conductance were not significant. We could not detect any activity of the antioxidant enzymes in the fumigated tobacco leaves. This is in spite of the fact that we were able to assay the enzymes in tobacco leaves grown in Israel. Conclusions. This project generated novel data, and potentially applicable to agriculture, on the differential response of lichens and tobacco to HNO3 and O3 pollutants. However, due to experimental problems and time limitation discussed in the body of the report, our data do not justify yet application for a full, 4-year grant. We hope that in the future we shall conduct more experiments related to our objectives, which will serve as a basis for a larger scale project to explore the possibility of using lichens and/or plants for biomonitoring of ozone and nitric acid air pollution.
5
Droby, Samir, Joseph W. Eckert, Shulamit Manulis, and Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
Full textAbstract:
One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.