Tesi sul tema "Detailed chemical kinetic mechanism"
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1
Davidson, Jeffrey E. "Combustion Modeling of RDX, HMX and GAP with Detailed Kinetics". BYU ScholarsArchive, 1996. https://scholarsarchive.byu.edu/etd/6531.
Abstract (sommario):
A one-dimensional, steady-state numerical model of the combustion of homogeneous solid propellant has been developed. The combustion processes is modeled in three regions: solid, two-phase (liquid and gas) and gas. Conservation of energy and mass equations are solved in the two-phase and gas regions and the eigenvalue of the system (the mass burning rate) is converged by matching the heat flux at the interface of these two regions. The chemical reactions of the system are modeled using a global kinetic mechanism in the two-phase region and an elementary kinetic mechanism in the gas region. The model has been applied to RDX, HMX and GAP. There is very reasonable agreement between experimental data and model predictions for burning rate, temperature sensitivity, surface temperature, adiabatic flame temperature, species concentration profiles and melt-layer thickness. Many of the similarities and differences in the combustion of RDX and HMX are explained from sensitivity analysis results. The combustion characteristics of RDX and HMX are similar because of their similar chemistry. Differences in combustion characteristics arise due to differences in melting temperature, vapor pressure and initial decomposition steps. A reduced mechanism consisting of 18 species and 39 reactions was developed from the Melius-Yetter RDX mechanism (45 species, 232 reactions). This reduced mechanism reproduces most of the predictions of the full mechanism but is 7.5 times faster. Because of lack of concrete thermophysical property data for GAP, the modeling results are preliminary but indicate what type of experimental data is necessary before GAP can be modeled with more certainty.
2
Shaheen, Zeiwar Hussein [Verfasser], Bernd [Akademischer Betreuer] Rogg e Viktor [Akademischer Betreuer] Scherer. "Development of detailed and reduced bio-diesel kinetic chemical mechanisms / Zeiwar Hussein Shaheen. Gutachter: Bernd Rogg ; Viktor Scherer". Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1082425818/34.
3
Dmitriev, Artëm. "Kinetic study of ester biofuels in flames". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0238.
Abstract (sommario):
Le progrès partout dans le monde nécessite une variété de sources d'énergie propre. Les biocarburants liquides de type ester semblent être très efficaces dans ce contexte, car ils sont faciles à utiliser dans les véhicules modernes, ils peuvent être produits à partir de diverses ressources renouvelables et ils offrent des caractéristiques de combustion respectueuses de l'environnement. À cet égard, les esters éthyliques d'acides gras (EEAG) sont considérés comme une classe prometteuse de biocarburants. L'objectif principal de cette thèse était de développer un mécanisme cinétique chimique actualisé de la combustion des EEAG légers jusqu'au pentanoate d'éthyle et de le valider par rapport aux nouvelles données expérimentales sur la structure de flammes laminaires prémélangées à basse pression et pression atmosphérique. Les flammes alimentées par trois EEAG, l'acétate d'éthyle, le butanoate d'éthyle et le pentanoate d'éthyle, ont été étudiées au moyen de la spectrométrie de masse avec faisceau moléculaire et de la chromatographie en phase gazeuse. Plus de 40 espèces stables et intermédiaires comprenant des radicaux ont été détectées et quantifiées dans les flammes. Une analyse complète du mécanisme développé a été réalisée. La thèse se compose de 3 chapitres. Le premier chapitre présente une revue bibliographique. Les études expérimentales et théoriques les plus importantes sur la combustion des EEAG sont discutées. Le deuxième chapitre présente un aperçu des méthodes expérimentales et de simulation utilisées dans la thèse. Des détails sur le développement du mécanisme sont également fournis dans cette partie. Le dernier chapitre présente des résultats expérimentaux et de modélisation sur les esters étudiés en comparaison avec les mécanismes cinétiques de la littératureGlobal progress all over the world requires a variety of clean energy sources. Liquid ester-based biofuels seem to be very effective in this context since they are easy to use in modern vehicles, they can be produced from a variety of renewable resources, and they provide environmentally friendly combustion characteristics. In this regard, fatty acid ethyl esters (FAEEs) are considered as a promising class of biofuels. The main goal of this thesis was to develop an updated chemical kinetic mechanism of combustion of light FAEEs up to ethyl pentanoate and validate it against the new experimental data on chemical speciation in low and atmospheric pressure premixed laminar flames. The flames fueled by three FAEEs, ethyl acetate, ethyl butanoate and ethyl pentanoate, were investigated by means of molecular-beam mass-spectrometry and gas-chromatography. More than 40 stable and intermediate species including radicals were detected and quantified in the flames. A comprehensive analysis of the developed mechanism was performed. The thesis consists of 3 chapters. In the first chapter a review of literature is presented. The most important experimental and theoretic studies on FAEEs are discussed. The second chapter presents an overview of experimental and simulation methods used in the work. Details on the mechanism development are also provided in this part. The last chapter present experimental and modeling results on the esters studied in comparison with the literature kinetic mechanisms
4
Maurice, Lourdes Quintana. "Detailed chemical kinetic models for aviation fuels". Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/8153.
5
Potter, Mark Lee. "Detailed chemical kinetic modelling of propulsion fuels". Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/7995.
6
Rizos, Konstantinos-Athanassios. "Detailed chemical kinetic modelling of homogeneous systems". Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407143.
7
Park, Sung-Woo. "Detailed chemical kinetic model for oxygenated fuels". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9599.
Abstract (sommario):
A detailed chemical kinetic model is developed and tested for the combustion of C2 and C3 oxygenated fuels such as ethanol, DME (dimethyl ether), acetone and n-propanol. It is validated by comparing predictions with experimental data on the structure of low pressure burner stabilised premixed flames and laminar burning velocities over a wide range of equivalence ratios. Data from shock tube and stirred reactor studies has also been considered. The elementary reactions of ethanol and DME oxidation have been studied extensively and were used as a starting point for extension to C3 oxygenated fuels. The chemistry of acetylene which is one of major intermediate species in higher hydrocarbon flames was also updated to improve the reliability of the present mechanism and acetylene laminar burning velocities and low-pressure premixed lean and rich flames were also computed. The detailed mechanism features more than 1500 reaction steps and 269 species. The structure of laminar premixed flames are predicted by using measured temperature profiles and conditions cover fuel-lean and fuel-rich mixtures at low pressure. The profiles of reactants, products and major intermediate species are compared to experimental data from mass spectrometry and the overall agreement between the kinetic model and experimental data is satisfactory. An analytic study of fuel consumption pathways is carried out to understand the detailed consumption pathways. The present mechanism is also tested against laminar flame speeds by calculating freely propagating premixed flames to extend the understanding of the combustion characteristics of oxygenated fuels. A sensitivity analysis is also performed.
8
Pacheco, Augusto Finger. "Analysis and reduction of detailed chemical kinetics mechanisms for combustion of ethanol and air". reponame:Repositório Institucional da UFSC, 2016. https://repositorio.ufsc.br/xmlui/handle/123456789/172793.
Abstract (sommario):
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2016.Made available in DSpace on 2017-01-31T03:11:16Z (GMT). No. of bitstreams: 1 343953.pdf: 3011153 bytes, checksum: 751769c238df128576bd611ed9f3178b (MD5) Previous issue date: 2016
Neste trabalho, três mecanismos detalhados de cinética química para o etanol, disponíveis na literatura, foram submetidos a diferentes métodos de redução, utilizando condições encontradas na operação normal de motores de combustão interna como parâmetros de redução. O primeiro mecanismo selecionado foi desenvolvido por Leplat e colaboradores (2011), no ICARE, em Orleans, França, contendo 252 reações químicas reversíveis, compreendendo 38 espécies, obtido principalmente para reproduzir medidas de concentrações de espécies em reatores perfeitamente misturados. O segundo por Mittal e colaboradores (2014), no C3-NUI, na Irlanda, envolvendo 710 reações químicas reversíveis, englobando 111 espécies, desenvolvido para prever os atrasos de ignição medidos em máquinas de compressão rápida. O terceiro mecanismo selecionado foi produzido por Cancino e colaboradores (2010), do IVG, Alemanha, e da UFSC, Brasil, contendo 1349 reações químicas reversíveis, compreendendo 35 espécies, feito principalmente para prever atrasos de ignição à alta pressão em tubos de choque. Os métodos de redução selecionados foram: Sensitivity Analysis (SA), Rate of Production (ROP), Direct Relation Graph (DRG), Direct Relation Graph with Error Propagation (DRGEP) e Path Flux Analysis (PFA). Sendo o mecanismo do Leplat o mais compacto, este foi utilizado para avaliar a redução final e a razão de convergência de cada método estudado. Ambos, atrasos de ignição (Ignition Delay Times, IDT) e velocidade de chama laminar, compreendidos em um grande intervalo de condições de temperatura, pressão e razão de equivalência foram selecionados como parâmetros de redução. Da análise inicial, os métodos DRG e DRGEP apresentaram as maiores eficiências, tanto em termos de tamanho final do mecanismo reduzido como nos termos de taxa de remoção de espécies. Assim, ambos os métodos foram sistematicamente aplicados nos outros mecanismos e as diferenças entre as espécies removidas foram avaliadas. O mecanismo final obtido via DRGEP para o mecanismo do Leplat apresentou, respectivamente, 84% e 72% das espécies e reações do mecanismo detalhado. Para o mecanismo do Cancino, o DRGEP apresentou uma maior redução, com 58% e 61% respectivamente das espécies e reações sem remover o mecanismo de oxidação do nitrogênio e ainda representando o IDT à altas pressões com uma diferença menor de 5% do mecanismo detalhado. Finalmente, para o mecanismo do Mittal, o método DRG apresentou a maior redução, atingindo 37% das espécies e 34% das reações do mecanismo detalhado. A análise de sensibilidade dos mecanismos reduzidos revelaram o mesmo grupo de reações como as mais sensíveis para a chama laminar e IDT dos apresentados pelos mecanismos detalhados, indicando que a redução não modifica a razão de importância das reações dentro de um caminho de reação para um dado mecanismo. Entretanto, ao comparar os mecanismos reduzidos entre si, muitas diferenças se tornam visíveis, como a modelagem dos fenômenos inicias ou finais da combustão. Estas observações podem auxiliar e dirigir o desenvolvimento de mecanismos cinéticos mais abrangentes para a modelagem da combustão de etanol.
Abstract : In this work, three detailed kinetic mechanisms available in the literature were subjected to different methods of reduction, using the conditions found on internal combustion engines normal operation as reduction targets. The mechanisms selected were those of Leplat and co-workers (2011), from ICARE, Orleans, France, containing 252 reversible chemical reactions among 38 chemical species, developed mainly to reproduce measurements of species concentration in perfectly-stirred reactors; of Mittal and co-workers (2014), from C3-NUI, Ireland, involving 710 reversible chemical reactions among 111 chemical species, developed mainly to predict ignition delay time measured in rapid compression machine; and that of Cancino and co-workers (2010), from IVG, Germany, and UFSC, Brazil, involving 1349 reversible chemical reactions among 135 chemical species, mainly developed to predict high-pressure ignition delay time measured in shock tubes. The reduction methods selected were the Sensitivity Analysis (SA), Rate of Production (ROP), Directed Relation Graph (DRG) and Directed Relation Graph with Error Propagation (DRGEP) and Path Flux Analysis (PFA). Since Leplat's mechanism is the most compact, it was selected for the assessment of the final reduction and convergence ratio involved in each reduction method studied. Both ignition delay time and laminar flame speed, evaluated over a large range of temperature, pressure and equivalence ratios, were selected as reduction targets. The maximum difference allowed between the predictions of the full detailed and the reduced mechanisms was 5 % over the entire target range. From the initial analysis, the DRG and DRGEP methods appeared as the most effective, both in terms of the size of the final reduced mechanism, as well as in terms of the rate of removal of species. The DRG and DRGEP methods were then systematically applied to the other mechanisms and the differences observed in the reduced species were noted and analyzed. The final reduced mechanism obtained via DRGEP from Leplat´s mechanism presented, respectively, 84 % and 72 % of the species and reactions of the detailed mechanism. For the Cancino mechanism, the DRGEP produced a larger reduction with 58 % and 61 % of species and reactions respectively of the detailed mechanism, without removing the nitrogen oxidation mechanism and still representing the high-pressure IDT with a 5% difference from the detailed mechanism. Finally, for the Mittal mechanism, the DRG method presented the largest reduction, reaching 37% of species and 34% of reactions of the detailed mechanism. The sensitivity analysis of the reduced mechanisms revealed the same group of most sensitive reactions in respect to the laminar flame and ignition delay time as the detailed mechanism, indicating that the reduction does not change the relative importance of the reactions within a reaction path for a given mechanism. However, when the reduced mechanisms are compared among them, several basic differences arise, mainly in the level of detail, expressed as the number of intermediates and reactions, placed in modeling early or late kinetics phenomena. These observations may lead to the development of more comprehensive mechanisms for the modeling of ethanol combustion.
9
Porter, Richard Thomas James. "Kinetic mechanism reduction for chemical process hazard application". Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441227.
10
Cho, Yong Kweon. "Kinetic and Chemical Mechanism of Pyrophosphate-Dependent Phosphofructokinase". Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc332128/.
Abstract (sommario):
Data obtained from isotope exchange at equilibrium, exchange of inorganic phosphate against forward reaction flux, and positional isotope exchange of 18O from the (βγ-bridge position of pyrophosphate to a (β-nonbridge position all indicate that the pyrophosphate-dependent phosphofructokinase from Propionibacterium freudenreichii has a rapid equilibrium random kinetic mechanism. All exchange reactions are strongly inhibited at high concentrations of the fructose 6-phosphate/Pi and MgPPi/Pi substrate-product pairs and weakly inhibited at high concentrations of the MgPPi/fructose 1,6-bisphosphate pair suggesting three dead-end complexes, E:F6P:Pi, E:MgPPi:Pi, and E:FBP:MgPPi. Neither back-exchange by [32p] nor positional isotope exchange of 18O-bridge-labeled pyrophosphate was observed under any conditions, suggesting that either the chemical interconversion step or a step prior to it limits the overall rate of the reaction. Reduction of the pyridoxal 5'-phosphate-inactivated enzyme with NaB[3H]4 indicates that about 7 lysines are modified in free enzyme and fructose 1,6-bisphosphate protects 2 of these from modification. The pH dependence of the enzyme-reactant dissociation constants suggests that the phosphates of fructose 6-phosphate, fructose 1,6-bisphosphate, inorganic phosphate, and Mg-pyrophosphate must be completely ionized and that lysines are present in the vicinity of the 1- and 6-phosphates of the sugar phosphate and bisphosphates probably directly coordinated to these phosphates. The pH dependence of kinetic parameters suggests that the enzyme catalyzes its reaction via general acid-base catalysis with the use of a proton shuttle. The base is required unprotonated in both reaction directions. In the direction of fructose 6-phosphate phosphorylation the base accepts a proton from the hydroxyl at C-l of F6P and then donates it to protonate the leaving phosphate. The maximum velocity of the reaction is pH independent in both reaction directions while V/K profiles exhibit pKs for binding groups (including enzyme and reactant functional groups) as well as pKs for enzyme catalytic groups. These data suggest that reactants bind only when correctly protonated and only to the correctly protonated form of the enzyme.
11
Tripathi, Rupali [Verfasser]. "Detailed Chemical Kinetic Modeling of Biofuels and their Blends with Conventional Fuel Components / Rupali Tripathi". Düren : Shaker, 2020. http://d-nb.info/1213471850/34.
12
Berdis, Anthony J. (Anthony Joseph). "Kinetic and Chemical Mechanism of 6-phosphogluconate Dehydrogenase from Candida Utilis". Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc278323/.
Abstract (sommario):
A complete initial velocity study of the 6-phosphogluconate dehydrogenase from Candida utilis in both reaction directions suggests a rapid equilibrium random kinetic mechanism with dead-end E:NADP:(ribulose 5-phosphate) and E:NADPH:(6- phosphogluconate) complexes. Initial velocity studies obtained as a function of pH and using NAD as the dinucleotide substrate for the reaction suggest that the 2'-phosphate is critical for productive binding of the dinucleotide substrate. Primary deuterium isotope effects using 3-
13
Bakhtina, Marina M. "Application of chemical probes to study the kinetic mechanism of DNA polymerases". Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1148915981.
14
Jiang, Mofen. "The Chemical and kinetic mechanism for leaching of chrysocolla by sulfuric acid". Thesis, The University of Arizona, 1992. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1992_610_sip1_w.pdf&type=application/pdf.
15
Tai, Chia-Hui. "Kinetic and Chemical Mechanism of O-Acetylserine Sulfhydrylase-B from Salmonella Typhimurium". Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc279064/.
Abstract (sommario):
Initial velocity studies of O-acetylserine sulfhydrylase-B (OASS-B) from Salmonella typhimurium using both natural and alternative substrates suggest a Bi Bi ping pong kinetic mechanism with double substrate competitive inhibition. The ping pong mechanism is corroborated by a qualitative and quantitative analysis of product and dead-end inhibition. Product inhibition by acetate is S-parabolic noncompetitive, indication of a combination of acetate with E followed by OAS. These data suggest some randomness to the OASS-B kinetic mechanism. The pH dependence of kinetic parameters was determined in order to obtain information on the acid-base chemical mechanism for the OASS-B reaction. A mechanism is proposed in which an enzyme general base accepts a proton from α-amine of O-acetylserine, while a second enzyme general base acts by polarizing the acetyl carbonyl assisting in the β-elimination of the acetyl group of O-acetylserine. The ε-amine of the active site lysine acts as a general base to abstract the α-proton in the β-elimination of acetate. At the end of the first half reaction the ε-amine of the active site lysine that formed the internal Schiff base and the general base are protonated. The resulting α-aminoacrylate intermediate undergoes a Michael addition with HS‾ and the active site lysine donates its proton to the α-carbon to give cysteine and regenerate enzyme to start the second half reaction. In addition, substrate specificity, stereochemistry of the internal Schiff base at C4', and sequence around active site lysine of O-acetylserine sulfhydrylase-A have been determined. The [4'-^3H]pyridoxamine generated by reduction of the internal Schiff base with sodium [^3H]borohydride retained most of its tritium after incubation with apoaspartate aminotransferase. These results agree with the hypothesis put forth by Dunathan (Dunathan, 1971; Dunathan and Voet, 1974) that a single surface (Re face) of the active site PLP is accessible to solvent. The sequence around the active site lysine is AsnProSerPheSerValLysCysArg.
16
KONOPKA, THIAGO FABRICIUS. "COMPARATIVE STUDY OF DETAILED CHEMICAL KINETIC MODELS OF SOOT PRECURSORS FOR ETHYLENE/AIR AND METHANE/AIR COMBUSTION". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=23399@1.
Abstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROEssa dissertação apresenta um estudo comparativo de quatro diferentes modelos de cinética química detalhada que envolvem as principais espécies químicas responsáveis pelo processo de formação e oxidação da fuligem, i.e., o oxigênio molecular, o radical hidroxila, o acetileno, o propargil, benzeno, fenil e pireno. Para este fim, considera-se a combustão de misturas de etileno/ar e metao/ar. Para analisar os modelos cinéticos são utilizados um reator perfeitamente misturado (PSR) e um reator parcialmente misturado (PaSR). No caso do reator perfeitamente misturado, um estudo sistemático da influência do tempo de residência e a riqueza da mistura sobre estas espécies químicas é apresentado. São discutidas as importantes discrepâncias obtidas, para o acetileno, o propargil, o benzeno, o fenil e o pireno, entre os modelos cinéticos analisados. As espécies oxidantes exibem menores discrepâncias dentre todas as espécies analisadas. No caso do reator parcialmente misturado, a razão entre o tempo de residência e o tempo de mistura é o parâmetro de análise. De modo geral, os resultados obtidos permitem avaliar o comportamento dos mecanismos cinéticos em uma situação representativa de combustão em escoamentos turbulentos.
In this dissertation a comparative study is presented of four different detailed kinetics models involving the main chemical species responsible for the soot formation and oxidation, i.e., the molecular oxygen, the hydroxyl, the acetylene, the propargyl, the benzene and the pyrene. To this purpose is considered the combustion of ethylene/air and metane/air. To analyze the kinetic models are used a perfect stirred reactor (PSR) and a partial stirred reactor (PaSR). In the case of a perfect stirred reactor a systematic study of the influence of the residence time and of the equivalence ratio on these chemical species is presented. Are discussed the important discrepancies obtained for acetylene, propargyl, benzene, phenyl and pyrene, between the kinetic models analyzed. The oxidizing species exhibit minor discrepancies only. In the case of the partially mixed reactor, the ratio between the residence time and the mixing time is the analysis parameter. Overall, the results obtained allow to evaluate the behavior of the kinetic mechanisms in situations representative of combustion in turbulent flows.
17
Cai, Liming [Verfasser]. "Chemical Kinetic Mechanism Development and Optimization for Conventional and Alternative Fuels / Liming Cai". Aachen : Shaker, 2016. http://d-nb.info/1118259327/34.
18
Frantom, Patrick Allen. "Studies of the chemical and regulatory mechanisms of tyrosine hydroxylase". Texas A&M University, 2006. http://hdl.handle.net/1969.1/3817.
Abstract (sommario):
Tyrosine hydroxylase (TyrH) catalyzes the pterin-dependent hydroxylation of
tyrosine to form dihydroxyphenylalanine. The enzyme requires one atom of ferrous iron
for activity. Using deuterated 4-methylphenylalanine substrates, intrinsic primary and
secondary isotope effects of 9.6 ± 0.9 and 1.21 ± 0.08 have been determined for benzylic
hydroxylation catalyzed by TyrH. The large, normal secondary isotope effect is
consistent with a mechanism involving hydrogen atom abstraction to generate a radical
intermediate. The similarity of the isotope effects to those measured for benzylic
hydroxylation catalyzed by cytochrome P-450 suggests that a high-valent, ferryl-oxo
species is the hydroxylating species in TyrH. Uncoupled mutant forms of TyrH have
been utilized to unmask isotope effects on steps in the aromatic hydroxylation pathway
which also implicate a ferryl-oxo intermediate. Inverse secondary isotope effects were
seen when 3,5-2H2-tyrosine was used as a substrate for several mutant enzyme forms.
This result is consistent with a direct attack by a ferryl-oxo species on the aromatic ring
of tyrosine forming a cationic intermediate. Rapid-freeze quench Mössbauer studies have provided preliminary spectroscopic evidence for an Fe(IV) intermediate in the reaction
catalyzed by TyrH.
The role of the iron atom in the regulatory mechanism has also been investigated.
The iron atom in TyrH, as isolated, is in the ferric form and must be reduced for activity.
The iron can be reduced by a number of one-electron reductants including
tetrahydrobiopterin, ascorbate, and glutathione; however, it appears that BH4 (kred = 2.8 ±
0.1 mM-1 s-1) is the most likely candidate for reducing the enzyme in vivo. A one-electron
transfer would require a pterin radical. Rapid-freeze quench EPR experiments aimed at
detecting the intermediate were unsuccessful, suggesting that it decays very rapidly by
reducing another equivalent of enzyme. The active Fe(II) form can also become oxidized
by oxygen (210 ± 30 M-1 s-1); this increases the affinity of catecholamine inhibitors.
Serine 40 can be phosphorylated to relieve the inhibition; however, results with S40E
TyrH show phosphorylation does not have an effect on the rate constant for reduction of
the enzyme but causes a 40% decrease in the rate constant of oxidation.
19
Matheu, David M. (David Michael) 1974. "Integrated pressure-dependence in automated mechanism generation : a new tool for building gas-phase kinetic models". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29294.
Abstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2003.Includes bibliographical references.
A host of vital, current, and developing technologies, such as pyrolysis, thermal cracking, partial oxidation, and high-efficiency combustion engines, involve complex, gas-phase chemical mechanisms with hundreds of species and thousands of reactions. Building complete, explicit chemical models by-hand for these systems is exceedingly difficult. The bias and intuition of the developers figure strongly in the resultant mechanism, causing important but unanticipated pathways to be ignored, and useless pathways to be included. Thus many chemists and engineers have tried artificial intelligence software tools, or "automated mechanism generators", to build large chemical mechanisms systematically. These tools employ graph-theory algebra, and "rate rules" - estimates of rate constants for classes of reactions - to construct automatically all the possibly important reactions and species for a given set of conditions. All of these tools have been severely hampered by their inability to capture the effects of pressure-dependence and falloff - even though these effects are important in almost every gas-phase system of interest to engineers and designers. Pressure-dependent reactions cannot be included using simple rate rules. Until now they presented an unresolved quandary for automated mechanism generators. This work presents the first automated method for including pressure-dependent reactions generally and systematically, on-the-fly, in computerized mechanism generation.
(cont.) The approach includes in the mechanism only those pressure-dependent pathways important for the conditions of interest, but can find any potentially important pressure-dependent reaction. It works by building partial pressure-dependent reaction networks, step-by-step, in harmony with a rate-based termination criteria which rationally controls overall mechanism size. It uses a fast, approximate method, the Quantum-Rice-Ramsperger-Kassel/Modified-Strong-Collision (QRRK/MSC), to predict rate constants k(T,P) employing only high-pressure-limit rate rules, pressure-dependent network structure, and heat capacity estimates. The error incurred by screening the pressure- dependent networks to include only important sections is small and bounded. Successful applications to various systems, including reactions through cycloalkyl intermediates, are presented. Application of this tool to methane pyrolysis revealed a new, unexpected mechanism. It explained the decades-old mystery of methane autocatalysis at low conversion, a phenomenon which had defied all "by-hand" attempts at mechanism development. Such work hints at the predictive power inherent in the next generation of automated mechanism builders.
by David M. Matheu.
Ph.D.
20
Crump, Brian R. "Kinetic study of the mechanism and side reactions in the hydrogen peroxide based production of chlorine dioxide". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/11322.
21
Pope, Christopher James. "A chemical mechanism for fullerenes C₆₀ and C₇₀ formation with kinetic modeling of their synthesis in flames". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12663.
22
Tripathi, Rupali [Verfasser], Heinz Günter [Akademischer Betreuer] Pitsch e S. Mani [Akademischer Betreuer] Sarathy. "Detailed chemical kinetic modeling of biofuels and their blends with conventional fuel components / Rupali Tripathi ; Heinz Pitsch, S. Mani Sarathy". Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://nbn-resolving.de/urn:nbn:de:101:1-2020080423315879685573.
23
Tripathi, Rupali Verfasser], Heinz Günter [Akademischer Betreuer] [Pitsch e S. Mani [Akademischer Betreuer] Sarathy. "Detailed chemical kinetic modeling of biofuels and their blends with conventional fuel components / Rupali Tripathi ; Heinz Pitsch, S. Mani Sarathy". Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1215171676/34.
24
Savage, Nicholas. "The use of a modified IQT™ apparatus and detailed chemical kinetic model to investigate the atmospheric autoignition characteristics of model fuels". Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/5474.
25
Mallick, Sushanta. "Kinetic mechanism of NAD-malic enzyme from Ascaris suum in the direction of reductive carboxylation of pyruvate". Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc332658/.
Abstract (sommario):
For this pseudoquadreactant enzymatic reaction (Mn2+ is a psuedoreactant), initial velocity patterns were obtained under conditions in which two substrates were maintained saturating while one reactant was varied at several fixed concentrations of the other.
26
Elias, Robert M. "The chemical reactivity of thermo mechanical pulp (TMP) fibres : a detailed kinetic study of the reaction between fibre and isolated fractions of hollcellulose and cellulose with succinic anhydride". Thesis, Bangor University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239884.
27
Poon, Hiew Mun. "Development of integrated chemical kinetic mechanism reduction scheme for diesel and biodiesel fuel surrogates for multi-dimensional CFD applications". Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33980/.
Abstract (sommario):
This thesis describes the research undertaken to formulate a systematic chemical kinetic mechanism reduction scheme to generate compact yet comprehensive chemical kinetic models for diesel and biodiesel fuels, for multi-dimensional Computational Fluid Dynamics (CFD) applications. The integrated mechanism reduction scheme was formulated based on the appraisal of various existing mechanism reduction techniques. It consists of five stages including Directed Relation Graph (DRG) with Error Propagation method using Dijkstra’s algorithm, isomer lumping, reaction path analysis, DRG method and adjustment of reaction rate constants. Consequently, a single-component diesel surrogate fuel model with only 79 species (i.e. n-hexadecane (HXNv2)) and a multi-component biodiesel surrogate fuel model (i.e. methyl decanoate/methyl-9-decenoate/n-heptane (MCBSv2)) with only 80 species were successfully derived from their respective detailed mechanisms, which contain thousands of species and elementary reactions. Here, both auto-ignition and jet-stirred reactor (JSR) conditions were applied as the data source for mechanism reduction. An overall 97 % reduction in mechanism size in terms of total number of species as well as an average 97 % reduction in computational runtime in zero-dimensional (0-D) chemical kinetic simulations was achieved. Both HXNv2 and MCBSv2 were also comprehensively validated in 0-D simulations in terms of ignition delay (ID) timings and species concentration profiles. Good agreement between the predictions and measurements was obtained throughout the test conditions. Subsequently, HXNv2 and MCBSv2 were integrated into the OpenFOAM-2.0.x solver to simulate spray combustion in a constant volume combustion chamber. The simulation results were validated against the experimental data of no.2 Diesel Fuel (D2) for diesel combustion and Soy Methyl Ester for biodiesel combustion. It was found that MCBSv2 was able to capture the combustion and soot formation events reasonably well. However, further refinement on HXNv2 was essential to improve the complex soot formation predictions. Fuel blending was then suggested to match the diesel fuel kinetics and compositions. As a result, two different versions of multi-component diesel surrogate fuel models were produced in the form of MCDS1 (HXNv2 + 2,2,4,4,6,8,8-heptamethylnonane (HMN)) and MCDS2 (HXNv2 + HMN + toluene + cyclohexane). All the fuel constituent reduced mechanisms and the integrated mechanisms were extensively validated in 0-D simulations under a wide range of shock tube and JSR conditions. Successively, the fidelity of the multi-component diesel surrogate fuel models was evaluated in two-dimensional spray combustion simulations. The computations were compared with the experimental data of D2 fuel. MCDS1 was found to be useful for simulations with less aromatic chemistry effects. In contrast, MCDS2 was a more appropriate surrogate model for fuels with aromatics and cyclo-paraffinic contents. Following that, fidelity of MCDS2 and MCBSv2 was further assessed in three-dimensional internal combustion engine simulations. The performance of the surrogate models was compared under the same operating conditions in a light-duty, direct injection diesel engine. The computed peak pressure and heat-release rate for biodiesel combustion were lower than diesel owing to the advanced ignition timing. The soot formation of biodiesel was also found to be 1.4 times lower than diesel due to oxygenated effects. Overall, the integrated reduction scheme proves to be an attractive approach for large-scale mechanism reduction to reduce the computational time-cost as well as to expedite multi-dimensional CFD computations.
28
Liu, Zhouyang. "Heterogeneous Catalytic Elemental Mercury Oxidation in Coal Combustion Flue Gas". University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1512045805884364.
29
Boz, Nezahat. "Kinetic Studies For The Production Of Tertiary Ethers Used As Gasoline Additives". Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605039/index.pdf.
Abstract (sommario):
ABSTRACT
KINETIC STUDIES FOR THE PRODUCTION OF TERTIARY ETHERS USED AS GASOLINE ADDITIVES
Boz, Nezahat
Ph. D., Department of Chemical Engineering
Supervisor: Prof. Dr. Timur Dogu
Co-supervisor: Prof. Dr. GülSen Dogu June 2004, 174 pages In the present study, the kinetics studies for etherification reactions were investigated in detail. In the first phase of present study, different acidic resin catalysts were prepared by the heat treatment of Amberlyst-15 catalysts at 220°
C at different durations of time and also by the synthesis of sulfonated styrene divinylbenzene cross-linked resins at different conditions. A linear dependence of reaction rate on hydrogen ion-exchange capacity was in 2M2B+ethanol reaction. However, in the case of 2M1B+ethanol reaction hydrogen ion-exchange capacities over 2.8 meq.H+/g did not cause further increase in reaction rate, which was concluded to be majorly due to significance of diffusional resistances. DRIFTS experiments carried out with alcohols, isobutylene, isoamylenes and TAME (tert-amyl-methyl-ether) in a temperature range of 333-353 K supported a Langmuir-Hinshelwood type reaction mechanism involving adsorbed isoolefins molecules forming a bridged structure between &ndash
SO3H sites of the catalyst and adsorbed alcohol molecules. A rate expression derived basing on the mechanism proposed from the DRIFTS results gave good agreement with the published data. Reaction rate was found to give a sharp maximum at ethanol activity of around 0.1. The third phase of this work included evaluation of effective diffusivities and adsorption equilibrium constants of methanol, ethanol and 2M2B, in Amberlyst-15 from moment analysis of batch adsorber dynamic results. Models proposed for monodisperse and bidisperse pore structures were used for the evaluation of effective diffusivities. It was shown that surface diffusion contribution was quite significant. In the last phase of the work, a batch Reflux-Recycle-Reactor (RRR) was proposed, modeled and constructed to achieve high yields and selectivities in equilibrium limited reactions. The batch reflux recycle reactor was modeled by assuming plug flow in the reactor section, perfect mixing in the reboiler and vapor-liquid equilibria between the liquid in the reboiler and reactor inlet stream. In this system conversion values of isoamylenes reaching to 0.91 were achieved at 82°
C with almost 100% selectivity. Such conversion values were shown to be much higher than the corresponding equilibrium values that could be obtained in vapor phase fixed bed reactors. The activation energies evaluated in this system were found to be much less than the activation energies evaluated in the fixed bed reactor studies. This was concluded to be majorly due to the significance of transport resistant in the batch Reflux-Recycle-Reactor in which catalyst particles are partially wet. As a result of catalyst development, characterization, kinetic and reactor development studies carried out in this study, it was concluded that tert-amyl-ethyl-ether (TAEE) could be effectively produced and used as a gasoline blending oxygenate.
30
Fox, Clayton D. L. "Modeling Simplified Reaction Mechanisms using Continuous Thermodynamics for Hydrocarbon Fuels". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37554.
Abstract (sommario):
Commercial fuels are mixtures with large numbers of components. Continuous thermodynamics is a technique for modelling fuel mixtures using a probability density function rather than dealing with each discreet component. The mean and standard deviation of the distribution are then used to model the chemical reactions of the mixture. This thesis develops the necessary theory to apply the technique of continuous thermodynamics to the oxidation reactions of hydrocarbon fuels. The theory is applied to three simplified models of hydrocarbon oxidation: a global one-step reaction, a two-step reaction with CO as the intermediate product, and the four-step reaction of Müller et al. (1992), which contains a high- and a low-temperature branch. These are all greatly simplified models of the complex reaction kinetics of hydrocarbons, and in this thesis they are applied specifically to n-paraffin hydrocarbons in the range from n-heptane to n-hexadecane. The model is tested numerically using a simple constant pressure homogeneous ignition problem using Cantera and compared to simplified and detailed mechanisms for n-heptane. The continuous thermodynamics models are able not only to predict ignition delay times and the development of temperature and species concentrations with time, but also changes in the mixture composition as reaction proceeds as represented by the mean and standard deviation of the distribution function. Continuous thermodynamics is therefore shown to be a useful tool for reactions of multicomponent mixtures, and an alternative to the "surrogate fuel" approach often used at present.
31
Sirjean, Baptiste. "Étude cinétique de réactions de pyrolyse et de combustion d'hydrocarbures cycliques par les approches de chimie quantique". Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL093N/document.
Abstract (sommario):
Les carburants dérivés du pétrole constituent la première source mondiale énergétique et leur approvisionnement constitue un défi actuel majeur impliquant des enjeux économiques et environnementaux cruciaux. Une des voies les plus efficaces pour peser simultanément sur ces deux enjeux passe par la diminution de la consommation en carburant. La simulation numérique constitue dès lors un outil précieux pour améliorer et optimiser les moteurs et les carburants. Les modèles chimiques détaillés sont nécessaires pour comprendre les phénomènes d’auto-inflammation et caractériser la nature et les quantités de polluants émis. Ces modèles mettent en jeu un nombre très important d’espèces et de réactions élémentaires, pour une espèce donnée et pour lesquelles la détermination des données thermodynamiques et cinétiques est un problème crucial. La chimie quantique constitue un outil précieux permettant d’une part de déterminer de façon précise les données thermocinétiques pour bon nombre de systèmes chimiques et d’autre part de mieux comprendre la réactivité de ces systèmes. Dans ce travail, les réactions unimoléculaires de décomposition d’hydrocarbures monocycliques et polycycliques (amorçages, réactions moléculaires, ß-scissions, formations d’éthers cycliques) ont été étudiées à l’aide des méthodes de la chimie quantique. Un mécanisme détaillé de pyrolyse d’un alcane polycyclique a été développé à partir des données thermodynamiques et cinétiques et des corrélations entre structure et réactivité déterminées pour les cyclanes à partir des calculs quantiques. Les simulations effectuées à partir de ce modèle sont en très bon accord avec les résultats expérimentaux de la littératurePetroleum fuels are the world’s most important primary energy source and the need to maintain their supply is a major actual challenge involving both economical and environmental features. Decreasing fuels consumption is one of the more efficient ways to reconcile the goals of energy price and environmental protection. Numerical simulations become therefore a very important tool to optimize fuels and motors. Detailed chemical kinetic models are required to reproduce the reactivity of fuels and to characterize the amount of emitted pollutants. Such models imply a very large number of chemical species and elementary reactions, for a given species, and the determination of thermodynamic and kinetic data is a critical problem. Nowadays, quantum chemistry methods are able to calculate accurately thermodynamic data for a large number of chemical systems and to elucidate the reactivity of these systems. In this work we have used quantum chemistry to study the unimolecular reactions (initiation, molecular reactions, ß-scissions, cyclic ethers formations) involved in the decomposition of monocyclic and polycyclic hydrocarbons. From the results of quantum chemical calculations, a detailed chemical kinetic mechanism of the pyrolysis of a polycyclic alkane has been developed and validated against experimental data
32
Kim, Youngseob. "Air quality modeling : evaluation of chemical and meteorological parameterizations". Phd thesis, Université Paris-Est, 2011. http://pastel.archives-ouvertes.fr/pastel-00667777.
Abstract (sommario):
The influence of chemical mechanisms and meteorological parameterizations on pollutant concentrations calculated with an air quality model is studied. The influence of the differences between two gas-phase chemical mechanisms on the formation of ozone and aerosols in Europe is low on average. For ozone, the large local differences are mainly due to the uncertainty associated with the kinetics of nitrogen monoxide (NO) oxidation reactions on the one hand and the representation of different pathways for the oxidation of aromatic compounds on the other hand. The aerosol concentrations are mainly influenced by the selection of all major precursors of secondary aerosols and the explicit treatment of chemical regimes corresponding to the nitrogen oxides (NOx) levels. The influence of the meteorological parameterizations on the concentrations of aerosols and their vertical distribution is evaluated over the Paris region in France by comparison to lidar data. The influence of the parameterization of the dynamics in the atmospheric boundary layer is important ; however, it is the use of an urban canopy model that improves significantly the modeling of the pollutant vertical distribution
33
Chatelain, Karl. "Etude de la stabilité à l'oxydation des carburants en phase liquide". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLY020/document.
Abstract (sommario):
La stabilité des carburants en phase liquide est de premier ordre dans le domaine du transport. Par exemple, les carburants, les lubrifiants ou les additifs doivent être stables de leur production jusqu'à leur utilisation. Cette thèse a pour but de développer et de valider une méthodologie alliant l’acquisition de données expérimentales et le développement de modèles cinétiques pour l'autoxydation en phase liquide.Expérimentalement, une approche complémentaire a été mise en place pour obtenir à la fois des données de réactivité globales via un appareil PetroOxy et des profils d’espèces via un autoclave instrumenté.Numériquement, une méthodologie basée sur un générateur de mécanismes est proposée pour obtenir une chimie détaillée en phase liquide. Les paraffines linéaires et branchées sont étudiées comme des carburants modèles représentatifs de l'autoxidation de carburants réels afin de valider l’approche proposée. Ces familles chimiques sont représentatives de la composition des carburants réels et alternatifs.La réactivité des n-paraffines de C8 à C16 ainsi que d’isomères de l’octane a été étudiée en PetroOxy sur la gamme de température 373-433 K. Puis, des profils d’espèces détaillés de la phase gaz et de la phase liquide ont été obtenus durant l’étude de l’oxydation du n-C8 et du 2-methylheptane dans un autoclave à 383 K et 10 bars. Des mécanismes cinétiques détaillés ont été développé pour toutes les molécules jusqu’à C14. Les mécanismes reproduisent qualitativement la formation des espèces majoritaires lors de l’autoxidation des alcanes ainsi que les tendances observées liées à la longueur de chaîne et la ramification. L’analyse des mécanismes cinétiques a mis en avant le rôle prédominant des radicaux peroxy (ROO) et peroxy-hydroperoxyde (HOOQOO) dans la consommation de carburants modèles.Cette étude a permis d’améliorer la compréhension des processus d’autoxidation des alcanes linéaires et branchés. L’étude de nouveaux systèmes permettra d’améliorer la compréhension globale des processus d’autoxidation et, de réduire l’écart de compréhension existant entre l’autoxidation des carburants réels et des carburants modèlesLiquid phase stability is a major concern in the transportation and the energy fields. Relevant examples are fuels, lubricants and additives which have to be stable from their production to their application (engine, combustors). This thesis aims to develop and validate a complete methodology combining both experimental data acquisition and the development of kinetic models for liquid phase autoxidation.The experimental methodology is based on a complementary approach to obtain (i) a global reactivity descriptor (Induction Periods) and (ii) detailed species profiles respectively using a PetroOxy device and an instrumented autoclave. Numerically, the presented methodology includes detailed liquid phase mechanisms generation with an automatic mechanism generator (RMG). Normal and iso-paraffins were selected as fuel surrogates for autoxidation to validate the developed methodology. They were selected regarding their large contribution in fuel composition and their growing interest as drop-in fuels.The reactivity of both n-paraffins from C8 to C16 and several C8 iso-paraffins was investigated over a wide temperature range (373-433 K) in the PetroOxy with liquid phase analyses. Then, detailed species profiles from the autoxidation of both n-octane and 2-methylheptane in autoclave were obtained at 383 K and 10 bars. Detailed liquid phase mechanisms were developed for all molecules tested up to C14. Mechanisms qualitatively reproduce the overall phenomenology of the chain length, the branching and the major species profiles observed experimentally. Mechanisms analysis allow to identify the main consumption pathways of alkanes through peroxy (ROO) and peroxy-hydroperoxide radicals (HOOQOO) over the temperature range investigated (373-473 K).This study permitted to increase the comprehension of autoxidation processes involved in normal and branched alkanes. The study of new chemical systems will increase the global comprehension of autoxidation processes and in fine it will reduce the gap between the current autoxidation knowledge and the real fuel autoxidation
34
Diaz, Aldana Luis A. "Mathematical Modeling of Ammonia Electro-Oxidation on Polycrystalline Pt DepositedElectrodes". Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1395077873.
35
Chatelain, Karl. "Etude de la stabilité à l'oxydation des carburants en phase liquide". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLY020.
Abstract (sommario):
La stabilité des carburants en phase liquide est de premier ordre dans le domaine du transport. Par exemple, les carburants, les lubrifiants ou les additifs doivent être stables de leur production jusqu'à leur utilisation. Cette thèse a pour but de développer et de valider une méthodologie alliant l’acquisition de données expérimentales et le développement de modèles cinétiques pour l'autoxydation en phase liquide.Expérimentalement, une approche complémentaire a été mise en place pour obtenir à la fois des données de réactivité globales via un appareil PetroOxy et des profils d’espèces via un autoclave instrumenté.Numériquement, une méthodologie basée sur un générateur de mécanismes est proposée pour obtenir une chimie détaillée en phase liquide. Les paraffines linéaires et branchées sont étudiées comme des carburants modèles représentatifs de l'autoxidation de carburants réels afin de valider l’approche proposée. Ces familles chimiques sont représentatives de la composition des carburants réels et alternatifs.La réactivité des n-paraffines de C8 à C16 ainsi que d’isomères de l’octane a été étudiée en PetroOxy sur la gamme de température 373-433 K. Puis, des profils d’espèces détaillés de la phase gaz et de la phase liquide ont été obtenus durant l’étude de l’oxydation du n-C8 et du 2-methylheptane dans un autoclave à 383 K et 10 bars. Des mécanismes cinétiques détaillés ont été développé pour toutes les molécules jusqu’à C14. Les mécanismes reproduisent qualitativement la formation des espèces majoritaires lors de l’autoxidation des alcanes ainsi que les tendances observées liées à la longueur de chaîne et la ramification. L’analyse des mécanismes cinétiques a mis en avant le rôle prédominant des radicaux peroxy (ROO) et peroxy-hydroperoxyde (HOOQOO) dans la consommation de carburants modèles.Cette étude a permis d’améliorer la compréhension des processus d’autoxidation des alcanes linéaires et branchés. L’étude de nouveaux systèmes permettra d’améliorer la compréhension globale des processus d’autoxidation et, de réduire l’écart de compréhension existant entre l’autoxidation des carburants réels et des carburants modèlesLiquid phase stability is a major concern in the transportation and the energy fields. Relevant examples are fuels, lubricants and additives which have to be stable from their production to their application (engine, combustors). This thesis aims to develop and validate a complete methodology combining both experimental data acquisition and the development of kinetic models for liquid phase autoxidation.The experimental methodology is based on a complementary approach to obtain (i) a global reactivity descriptor (Induction Periods) and (ii) detailed species profiles respectively using a PetroOxy device and an instrumented autoclave. Numerically, the presented methodology includes detailed liquid phase mechanisms generation with an automatic mechanism generator (RMG). Normal and iso-paraffins were selected as fuel surrogates for autoxidation to validate the developed methodology. They were selected regarding their large contribution in fuel composition and their growing interest as drop-in fuels.The reactivity of both n-paraffins from C8 to C16 and several C8 iso-paraffins was investigated over a wide temperature range (373-433 K) in the PetroOxy with liquid phase analyses. Then, detailed species profiles from the autoxidation of both n-octane and 2-methylheptane in autoclave were obtained at 383 K and 10 bars. Detailed liquid phase mechanisms were developed for all molecules tested up to C14. Mechanisms qualitatively reproduce the overall phenomenology of the chain length, the branching and the major species profiles observed experimentally. Mechanisms analysis allow to identify the main consumption pathways of alkanes through peroxy (ROO) and peroxy-hydroperoxide radicals (HOOQOO) over the temperature range investigated (373-473 K).This study permitted to increase the comprehension of autoxidation processes involved in normal and branched alkanes. The study of new chemical systems will increase the global comprehension of autoxidation processes and in fine it will reduce the gap between the current autoxidation knowledge and the real fuel autoxidation
36
Critchfield, Brian L. "Statistical Methods For Kinetic Modeling Of Fischer Tropsch Synthesis On A Supported Iron Catalyst". Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1670.pdf.
37
Husson, Benoît. "Étude en réacteur auto-agité par jets gazeux de l'oxydation d'hydrocarbures naphténiques et aromatiques présents dans les gazoles". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0041/document.
Abstract (sommario):
L'étude de l'oxydation d'hydrocarbures naphténiques (éthyl-cyclohexane, n-butyl-cyclohexane) et aromatiques (éthyl-benzène, n-butyl-benzène, n-hexyl-benzène) a été réalisée en réacteur auto-agité par jets-gazeux (pression de 1 à10 bar, température de500 à1100 K, richesse : 0,25, 1 et 2, temps de passage:2s). Les produits de réaction ont été quantifiés par chromatographie en phase gazeuse et identifiés par couplage avec la spectrométrie de masse. L'influence sur la réactivité et sur la sélectivité de la richesse, de la pression et de la taille de la chaîne alkyle greffée sur le cycle aromatique ou naphténique a été déterminée. La réactivité de l'éthyl-cyclohexane a également été comparée à celle obtenue pour deux autres composés contenant 8 atomes de carbone (le n-octane et le 1-octène). Les résultats expérimentaux pour l'éthyl-cyclohexane et le n-butyl-benzène sont en bon accord avec des prédictions réalisées à l'aide de modèles de la littérature, sauf pour le composé naphténique pour des températures inférieures à 800 K. Un mécanisme cinétique détaillé d'oxydation de l'éthyl-benzène a été développé (1411 réactions ; 205 espèces) et validé à partir des résultats obtenus lors de cette thèse mais également à partir de résultats disponibles dans la littérature. Ce mécanisme constitue la « base aromatique » implémentée dans le nouveau logiciel EXGAS Alkyl-aromatiques développé parallèlement à cette thèse et qui permet la génération automatique de mécanismes cinétiques d'oxydation des composés Alkyl-aromatiques. Une étude des règles génériques de décomposition des espèces primaires dans le mécanisme secondaire de ce logiciel a été réalisée lors de cette thèseThe study of the oxidation of naphthenic (ethyl-cyclohexane,n-butyl-cyclohexane) and aromatic (ethyl-benzene,n-butyl-benzene, n-hexyl-benzene) hydrocarbons was performed in a jet-stirred reactor (pressure from 1 to10 bar, temperature from 500 to 1100 K, equivalenceratio: 0.25, 1 and2, residence time: 2s). Reaction products were quantified by gas chromatography and identified using mass spectrometry. The influence on the reactivity and the product selectivity of the equivalence ratio, the pressure and the size of the side alkyl chain attached tothe aromatic or naphthenic ringwas determined. The reactivity of ethyl-cyclohexane was also compared to that obtained for two other compounds containing 8 carbon atoms (n-octane and1-octene). The experimental results for ethyl-cyclohexane and n-butyl-benzene have been satisfactorily compared with prediction made using detailed kinetic mechanisms from the literature, except for the naphthenic at temperature below 800 K. A detailed kinetic mechanismfor the oxidation of ethyl-benzene has been developed (1411 reactions, 205 species) and validated from experimental results obtained in this studybut also from results available in literature. This mechanism has now becomethe "aromatic base" implemented in the software EXGAS Alkyl-aromaticswhich has been developed together with this PhD work and which allows theautomatic generation of alkyl-aromatics oxidation kinetic mechanisms. A study of the generic rules of decomposition of primary species in the secondary mechanism of this softwarewas conducted in this thesis
38
Tilland, Airy. "Étude de l’évolution de la réactivité des matériaux porteurs d’oxygène dans un procédé de combustion en boucle chimique". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0218/document.
Abstract (sommario):
Le procédé de captage du dioxyde de carbone (CO2) par combustion fonctionnant en boucle chimique (Chemical Looping Combustion (CLC)) permet de produire de l’énergie à partir du méthane tout en captant le CO2 produit par la combustion. Ce procédé met en oeuvre un matériau porteur d’oxygène (NiO/NiAl2O4) qui est utilisé pour fournir de l’oxygène lors de la combustion du méthane et qui est ensuite régénéré sous air. Le matériau utilisé se dégrade au cours du temps ce qui accroît les coûts du procédé et diminue ses performances. L’étude présentée ici a pour objectif de déterminer quel est l’impact des phénomènes thermiques et chimiques sur la dégradation du matériau porteur d’oxygène. Les mécanismes réactionnels représentant la réduction et l’oxydation du porteur d’oxygène ont été déterminés et validés grâce à des études expérimentales et à la modélisation d’un réacteur parfaitement auto-agité (RPAA) et d’un réacteur à écoulement piston. L’importance du contrôle du dépôt de carbone dans le procédé a été démontrée. Ensuite, les paramètres cinétiques des réactions représentant la réduction de l’oxyde de nickel ont pu être déterminés grâce à un modèle original du RPAA, puis validés dans le réacteur piston. L’intérêt du RPAA pour la détermination de paramètres cinétiques dans le cas du procédé CLC a été présenté. Les paramètres obtenus permettent de prédire de manière correcte toutes les réactions même si un travail complémentaire est nécessaire pour obtenir une meilleure précision des résultats. Finalement, un mécanisme de dégradation du matériau porteur d’oxygène déduit des résultats expérimentaux a été proposé. Ce mécanisme décrit la production importante de fines particules se dissociant des grains et leur rôle dans les phénomènes d’agglomération observés. Le matériau support, supposé inerte, jouerait un rôle dans l’apport d’oxygène. La méthodologie développée dans ce travail pourrait être adaptée à l’analyse et la caractérisation d’autres matériaux porteurs d’oxygèneThe Chemical Looping Combustion (CLC) process produces energy by combustion of methane while capturing the carbon dioxide (CO2). An oxygen carrier (NiO/NiAl2O4) is used to deliver oxygen during the combustion of methane. It is then regenerated by air. The oxygen carrier material degrades over time, which increases the costs of the process and reduces its performance. The present study aims at determining the impacts of thermal and chemical phenomena on the oxygen carrier degradations. The reaction mechanisms corresponding to the reduction and oxidation of the oxygen carrier are determined and validated through experimental studies and the modeling of a continuously auto-stirred tank reactor (CASTR) and a plug flow reactor. The importance of controlling the quantity of deposited carbon in the process is illustrated. Then, the kinetic parameters of the reactions representing the reduction of nickel oxide are determined with an original model of the CASTR and validated in the plug flow reactor. The interest of using the CASTR for the determination of kinetic constants of the reactions involved in CLC process is presented. The obtained parameters give a good description of all reactions even if additional work is required to obtain a better precision of the results. Finally, a degradation mechanism of the oxygen carrier has been proposed. This mechanism describes the large production of fine particles separated from the grains and their role in the observed agglomeration phenomena. The support material, supposed to be inert, provides some of its oxygen. The methodology developed in this work could be adapted for the analysis and the characterization of other oxygen-carriers
39
Lannuzel, Frédéric. "Influence des aromatiques sur la stabilité thermique des pétroles dans les gisements". Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2007. http://tel.archives-ouvertes.fr/tel-00473215.
Abstract (sommario):
Cette étude vise à mieux comprendre les réactions mpliquées dans le craquage thermique des huiles en basins sédimentaires. Des pyrolyses d'octane, de toluène et de mélanges octane/toluène ont été effectuées entre 330°C et 450°C et des pressions allant de 1 bar à 700 bar. Le mécanisme radicalaire développé permet de rendre compte de l'influence de la température et de la pression sur la distribution des produits ainsi que sur la conversion jusqu'aux conditions de gisement (200°C, 150-1000 bar). Les pyrolyses du toluène pur et du mélange octane/toluène ont permis de modéliser le rôle inhibiteur des alkylaromatiques sur le craquage des hydrocarbures. Cette étude démontre l'importance des co-réactions et donc de la composition des huiles sur la stabilité thermique des pétroles en gisements.
40
Tang, Shiao-Shek, e 唐嘯石. "Kinetic and Chemical Mechanism of Octopus Digestive Gland". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/94741434429315370625.
41
Ravi, Kiran Mandapaka. "Development of noble metal catalysts and detailed kinetic models for CO oxidation and water gas shift reactions". Thesis, 2018. https://etd.iisc.ac.in/handle/2005/5488.
Abstract (sommario):
Noble metal (Pt, Pd, Rh) based catalysts have been highly effective for CO abatement applications such as CO oxidation and the water gas shift reaction (WGS). In the venture for development of novel catalysts, noble metal supported catalysts have been developed with support materials ranging from inert metal oxides such as ZrO2, SiO2, carbonaceous graphene oxide and reducible supports such as CeO2, TiO2 and cobalt oxide.
In contrast to the impregnated catalysts, monometallic and bimetallic noble metal substituted ionic catalysts have been developed and were demonstrated to have superior catalytic activity for CO oxidation and WGS. However, despite abundant experimental data and spectroscopic insights, the reaction mechanisms, kinetic models and the rate expressions developed for gas phase reactions over noble metal based catalysts are still points of debate with no consensus. This is particularly evident for bimetallic catalysts and noble metal based reducible catalysts. This lack of comprehensive kinetic models can be attributed to the deficiency of intuitive understanding of reaction mechanisms and
Name
Mandapaka Ravikiran
Sr No
05-04-00-10-12-13-1-10418
Department
Chemical Engineering
Advisor
Prof. Giridhar Madras (Dept. of Chemical Engg)
Title
Development of noble metal catalysts and detailed kinetic models for CO oxidation and water gas shift reactions.
robust modeling procedures accounting for the contribution of the support materials in the reaction mechanisms.
With the advent of robust simulation protocols, and spectroscopy based instrumentation it has now been possible to investigate the energetics of complex reaction mechanisms involving gas-phase reactions through DFT calculations and probe the mechanistic insights using FTIR based experiments. These advancements can be decisive in developing detailed kinetic models or microkinetic models for various gas phase reactions over reducible oxides. In order to address the aforementioned issues, this thesis emphasizes on the comprehensive development and application of novel noble metal based catalysts for CO oxidation and WGS starting from the catalyst synthesis, characterizations, activity testing and detailed kinetic model development.
Chapter 1 of the thesis presents the need for development of efficient catalyst for CO abatement applications. It presents the literature background on the usage of noble metal based catalysts and their application in conjunction with different support materials. The chapter also presents various synthesis procedures, experimental protocols, drawbacks and complications involved in the synthetic procedures. This chapter also illustrates various reaction mechanisms, rate expressions developed in the literature for CO oxidation and WGS reaction catalyzed by noble metals.
Chapter 2 of the thesis presents the synthesis protocols implemented in this thesis to synthesize various noble metal ionic catalysts i.e. palladium doped, platinum co-doped and rhodium co-doped ceria catalysts. The chapter presents the XRD, XPS, TEM characterizations, of the catalysts presenting the crystal structure, surface morphology,
structural parameters and ionic state of the respective consistent elements of the catalysts. The chapter also presents the BET surface area of the catalysts and H2-TPR profiles of the catalysts illustrating the oxygen storage capacity of the catalysts.
Chapter 3 of the thesis discusses the development of kinetic models and rate expressions for different noble metal based catalysts involving single site and dual site mechanisms. This chapter gives a brief overview of the methodology followed to obtain and design rate expressions for microkinetic models for CO oxidation and WGS over various noble metal based catalysts.
Chapters 4, 5 and 6 of the thesis present the experimental protocols, catalytic activity and reaction mechanisms of various noble metal catalysts i.e. palladium doped, platinum co-doped, rhodium co-doped ceria, Fe-Pt/GO and Pd/SiO2 for WGS reaction and CO oxidation, respectively. These chapters illustrate the application of differential reactor proximity approach followed for obtaining the intrinsic rate of reactions, comparison of activity of the catalyst using apparent activation energies for noble metal ionic catalysts and Fe-Pt bi metallic catalysts. Chapter 6 also presents the development and validation of the microkinetic models developed for CO oxidation using isothermal plug flow approach for bi-metallic Fe-Pt/GO catalysts and palladium impregnated silica catalyst.
Chapter 7 of the thesis presents the conclusions of the various applications of the ionic catalysts for CO abatement reactions illustrating the activity of the developed catalysts. The chapter also illustrates the validity and robustness of the kinetic modeling
procedures implemented in the above studies to understand the intrinsic kinetics of the reactions.
Chapter 7 of the thesis also presents the scope and orientation for future work in the field of catalyst development and kinetic modeling for various gas phase reactions such as preferential oxidation and reforming reactions with applications involving various side reactions.
42
Woo, Joseph L. "Gas-Aerosol Model For Mechanism Analysis: Kinetic Prediction Of Gas- And Aqueous-Phase Chemistry Of Atmospheric Aerosols". Thesis, 2014. https://doi.org/10.7916/D81N7Z3G.
Abstract (sommario):
Atmospheric aerosols are a major contributor to the total energy balance of the Earth's atmosphere. The exact effect of these aerosols on global climate is not well understood, due to poorly-characterized compositional variation that takes place over a given aerosol's lifetime. Organic aerosol (OA) species are of particular interest, forming through a myriad of gas- and aerosol-phase mechanisms and contributing to aerosol light absorbance, cloud formation properties, and overall particle lifetime. As different organic species will affect physical properties in different ways, proper prediction of these compounds forming in the aerosol phase is necessary to estimate the net physical properties of aerosols, and subsequently their effects on overall global climate. Several previous models exist that attempt to predict organic components of aqueous-phase mass in aerosols, with varying degrees of scope of chemistry and range of applicability. Many of such simulations emphasize OA formation via oxidation of gas-phase organic species that results in low-volatility compounds that subsequently partition into aerosols. Other models focus on aqueous-phase processing of semi-volatile and non-volatile water-soluble organic compounds (WSOC's) under cloud water conditions. However, aqueous reactions that occur in atmospheric, deliquesced salt aerosols have recently also been found to be potentially important additional pathway for the creation of additional aerosol-phase organic mass, contributing different products due to the significantly higher inorganic concentrations present under these conditions. It is desirable to incorporate these reactions into analogous predictive simulations, allowing for the chemistry taking place in small, deliquesced salt atmospheric aerosols to be more accurately represented. In this work, we discuss a new photochemical box model known as GAMMA, the Gas-Aerosol Model for Mechanism Analysis. GAMMA couples gas-phase organic chemistry with highly detailed aqueous-phase chemistry, yielding speciated predictions for dozens of secondary organic aqueous aerosol-phase compounds under various atmospheric and laboratory initial conditions. From these studies, we find that isoprene-derived epoxides (IEPOX) and their substitution products are predicted to dominate aqueous-phase organic aerosol mass in conditions with low NOx in the atmosphere, representative of rural environments. The contribution of these epoxide species is expected to be high under acidic conditions, though our findings still estimate significant contribution to aqueous-phase organic mass under higher pH or under cloudwater conditions, when acidity is expected to be lower. Under high-NOx conditions typical of urban environments, glyoxal is seen to form the majority of evolved aqueous organic species, with organic acids comprising the bulk of the difference. We then implement a series of physical property modules, designed to predict changes in aerosol absorbance and surface tension due to bulk concentrations of evolved OA species. Preliminary results from these modules indicate that bulk solution effects of aqueous-phase carbonyl-containing volatile organic compounds (CVOCs) and organic acids are insufficient to significantly affect net aerosol surface tension under any condition tested, implying that observed deviations from pure inorganic aerosol surface tension will arise from surface-aerosol partitioning rather than bulk compositional effects. Light absorption of aqueous aerosols is seen to be driven by dark glyoxal chemistry in deliquesced salt aerosols and organic acids in cloud droplets, though additional information about the absorbance properties of IEPOX and its derivatives is required to accurately predict the net absorbance of aerosols where these species dominate OA mass. The predictions as described by GAMMA are comparable to field observations, and give further credence to the significance of epoxide formation as a source of aqueous-phase organic aerosol mass. These results also suggest the relative importance of specific organic compounds in the aqueous phase of both deliquesced salt aerosols and cloud droplets in the atmosphere, which gives direction to the study of compounds whose impact on aerosol physical properties will matter the most. In turn, new kinetic and physical information can be directly applied into the groundwork laid here, allowing GAMMA to provide a continuously better understanding of the effect of organic material on aqueous aerosols and their implicit effect on the environment.
43
"Computational Analyses of Complex Flows with Chemical Reactions". Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.14749.
Abstract (sommario):
abstract: The heat and mass transfer phenomena in micro-scale for the mass transfer phenomena on drug in cylindrical matrix system, the simulation of oxygen/drug diffusion in a three dimensional capillary network, and a reduced chemical kinetic modeling of gas turbine combustion for Jet propellant-10 have been studied numerically. For the numerical analysis of the mass transfer phenomena on drug in cylindrical matrix system, the governing equations are derived from the cylindrical matrix systems, Krogh cylinder model, which modeling system is comprised of a capillary to a surrounding cylinder tissue along with the arterial distance to veins. ADI (Alternative Direction Implicit) scheme and Thomas algorithm are applied to solve the nonlinear partial differential equations (PDEs). This study shows that the important factors which have an effect on the drug penetration depth to the tissue are the mass diffusivity and the consumption of relevant species during the time allowed for diffusion to the brain tissue. Also, a computational fluid dynamics (CFD) model has been developed to simulate the blood flow and oxygen/drug diffusion in a three dimensional capillary network, which are satisfied in the physiological range of a typical capillary. A three dimensional geometry has been constructed to replicate the one studied by Secomb et al. (2000), and the computational framework features a non-Newtonian viscosity model for blood, the oxygen transport model including in oxygen-hemoglobin dissociation and wall flux due to tissue absorption, as well as an ability to study the diffusion of drugs and other materials in the capillary streams. Finally, a chemical kinetic mechanism of JP-10 has been compiled and validated for a wide range of combustion regimes, covering pressures of 1atm to 40atm with temperature ranges of 1,200 K - 1,700 K, which is being studied as a possible Jet propellant for the Pulse Detonation Engine (PDE) and other high-speed flight applications such as hypersonic missiles. The comprehensive skeletal mechanism consists of 58 species and 315 reactions including in CPD, Benzene formation process by the theory for polycyclic aromatic hydrocarbons (PAH) and soot formation process on the constant volume combustor, premixed flame characteristics.Dissertation/Thesis
Ph.D. Aerospace Engineering 2012
44
Eser, Bekir Engin. "Spectroscopic and Kinetic Investigation of the Catalytic Mechanism of Tyrosine Hydroxylase". 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7355.
Abstract (sommario):
Tyrosine Hydroxylase (TyrH) is a pterin-dependent mononuclear non-heme iron
oxygenase. TyrH catalyzes the hydroxylation reaction of tyrosine to
dihydroxyphenylalanine (DOPA). This reaction is the first and the rate-limiting step in
the biosynthesis of the catecholamine neurotransmitters. The active site iron in TyrH is
coordinated by the common facial triad motif, 2-His-1-Glu. A combination of kinetic
and spectroscopic techniques was applied in order to obtain insight into the catalytic
mechanism of this physiologically important enzyme.
Analysis of the TyrH reaction by rapid freeze-quench Mossbauer spectroscopy
allowed the first direct characterization of an Fe(IV) intermediate in a mononuclear nonheme
enzyme catalyzing aromatic hydroxylation. Further rapid kinetic studies
established the kinetic competency of this intermediate to be the long-postulated
hydroxylating species, Fe(IV)O.
Spectroscopic investigations of wild-type (WT) and mutant TyrH complexes
using magnetic circular dichroism (MCD) and X-ray absorption spectroscopy (XAS)
showed that the active site iron is 6-coordinate in the resting form of the enzyme and that binding of either tyrosine or 6MPH4 alone does not change the coordination. However,
when both tyrosine and 6MPH4 are bound, the active site becomes 5-coordinate, creating
an open site for reaction with O2. Investigation of the kinetics of oxygen reactivity of
TyrH complexes in the absence and presence of tyrosine and/or 6MPH4 indicated that
there is a significant enhancement in reactivity in the 5-coordinate complex in
comparison to the 6-coordinate form. Similar investigations with E332A TyrH showed
that Glu332 residue plays a role in directing the protonation of the bridged complex that
forms prior to the formation of Fe(IV)O.
Rapid chemical quench analyses of DOPA formation showed a burst of product
formation, suggesting a slow product release step. Steady-state viscosity experiments
established a diffusional step as being significantly rate-limiting. Further studies with
stopped-flow spectroscopy indicated that the rate of TyrH reaction is determined by a
combination of a number of physical and chemical steps.
Investigation of the NO complexes of TyrH by means of optical absorption,
electron paramagnetic resonance (EPR) and electron spin echo envelope modulation
(ESEEM) techniques revealed the relative positions of the substrate and cofactor with
respect to NO, an O2 mimic, and provided further insight into how the active site is
tuned for catalytic reactivity upon substrate and cofactor binding.
45
Xia, Guoyun. "Modeling secondary organic aerosol formation using a simple scheme in a 3-dimensional air quality model and performing systematic mechanism reduction for a detailed chemical system /". 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19790.
Abstract (sommario):
Thesis (Ph.D.)--York University, 2006. Graduate Programme in Earth and Space Science.Typescript. Includes bibliographical references (leaves 271-296). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19790
46
Clancy, Kathleen. "Determination of the Kinetic and Chemical Mechanism of a Unique Peptidoglycan Recycling Enzyme with Dual Hydrolase and Kinase Functionality: Anhydromuramic Acid Kinase, AnmK". Diss., 2012. http://hdl.handle.net/10161/5820.
Abstract (sommario):
Antibiotic resistance is a crisis in modern society causing increasing rates of bacterial infections impervious to current therapies. To this end, new targets for antimicrobial treatment must be pursued. Peptidoglycan recycling is an understudied key life process in the bacterial cell where over 60% of cell wall materials are reused during each turnover. Anhydro-N-acetylmuramic acid kinase, AnmK is a novel enzyme in this pathway catalyzing the conversion of anhydro-N-acetylmuramic acid to N-acetylacetylmuramic acid-6-phosphate in the presence of magnesium and ATP. Previously, several crystal structures of AnmK have been solved providing insights into the catalytic mechanism, but until this point, no extensive work has been done. The goal of this work is to determine the chemical and kinetic mechanisms of AnmK. This will be completed using a continuous assay for dual hydrolysis and phosphorylation activity as well as a novel assay for carbohydrate hydrolysis. Substrate interactions will be probed using previous crystal structures as a guide. Finally, pre-steady-state studies will conclude the mechanistic studies giving a full depiction of AnmK catalysis.
The kinetic and chemical mechanisms of AnmK are studied in the steady-state using a continuous assay format where bisubstrate kinetics as well as inhibitor studies were performed as well as substrate specificity studies. pH rate profiles and solvent isotope exchange were used to determine the residues involved in catalysis.
The concerted or stepwise nature of hydrolysis and phosphorylation is a main question of this work. A novel assay using glucose oxidase was executed to trap any chemical intermediates formed in a potential stepwise reaction. This assay was used on wild-type AnmK as well as a variety of mutants. Through these experiments, two key residues in phosphoryl transfer are identified and used to partially decouple hydrolysis and phosphorylation.
Mechanistic studies were continued by investigating the pre-steady-state kinetics of AnmK using a quench flow apparatus. Wild-type AnmK showed no appearance of a chemical intermediate during timepoints as short as 10 ms and also showed a linear formation of product with a catalytic rate analogous to the steady-state rate. These results indicate that AnmK undergoes a concerted, one-step catalytic mechanism with no chemical intermediate. AnmK E330A formed both hydrolysis product, as well as hydrolysis and phosphorylation product in the pre-steady-state agreeing with the previous results that hydrolysis and phosphorylation had been partially decoupled.
These results show the chemical and kinetic mechanism of a novel enzyme with previously undocumented concomitant hydrolysis and phosphorylation. This work provides further understanding of carbohydrate-modifying enzymes as well as the peptidoglycan recycling pathway. A better understanding of peptidoglycan biosynthesis and recycling could lead to novel antimicrobial therapies in the future.
Dissertation