Gotowe bibliografie tematyczne / CO oxidation reaction

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Gotowa bibliografia na temat „CO oxidation reaction”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "CO oxidation reaction"

Zhou, Xue-Fei, i Jing Liu. "Co(salen) catalysed oxidation of synthetic lignin-like polymer: Co(salen) effects". Chemical Industry 66, nr 5 (2012): 685–92. http://dx.doi.org/10.2298/hemind120124031z.

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In this paper, Co(salen) [salen = N, N?-bis(salicylidene)ethylenediamine] complex was studied as oxygen activators for the catalytic oxidation of a lignin model polymer using water as the solvent, with molecular oxygen and hydrogen peroxide as the oxidants. The effect of Co(salen) on oxidation was tested by spectroscopic methods (FTIR, 13C-NMR and GC-MS). The reactions catalysed by Co(salen) included C?-alcohol oxidation, C?-C? side chain cleavage, demethoxylation, aromatic ring cleavage, and ?-O-4 cleavage. In addition to the mechanistic information obtained, the effect of Co(salen) suggests that Co(salen) can be important for the catalytic oxidation, as they affect the oxidation of lignin model polymer. The reaction performed in the presence of Co(salen) was more efficient than without it. The formation of aldehyde in the catalytic oxidation, as shown by GC-MS, could be identified as the mechanism of oxidative cleavage of the ?-O-4 bonds.

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Ma, Guoyan, Le Wang, Xiaorong Wang, Lu Li i Hongfei Ma. "CO Oxidation over Alumina-Supported Copper Catalysts". Catalysts 12, nr 9 (10.09.2022): 1030. http://dx.doi.org/10.3390/catal12091030.

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CO oxidation, one of the most important chemical reactions, has been commonly studied in both academia and the industry. It is one good probe reaction in the fields of surface science and heterogeneous catalysis, by which we can gain a better understanding and knowledge of the reaction mechanism. Herein, we studied the oxidation state of the Cu species to seek insight into the role of the copper species in the reaction activity. The catalysts were characterized by XRD, N2 adsorption-desorption, X-ray absorption spectroscopy, and temperature-programmed reduction. The obtained results suggested that adding of Fe into the Cu/Al2O3 catalyst can greatly shift the light-off curve of the CO conversion to a much lower temperature, which means the activity was significantly improved by the Fe promoter. From the transient and temperature-programmed reduction experiments, we conclude that oxygen vacancy plays an important role in influencing CO oxidation activity. Adding Fe into the Cu/Al2O3 catalyst can remove part of the oxygen from the Cu species and form more oxygen vacancy. These oxygen vacancy sites are the main active sites for CO oxidation reaction and follow a Mars-van Krevelen-type reaction mechanism.

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Eid, Kamel, Yahia Ahmad, Assem Mohamed, Anas Elsafy i Siham Al-Qaradawi. "Versatile Synthesis of Pd and Cu Co-Doped Porous Carbon Nitride Nanowires for Catalytic CO Oxidation Reaction". Catalysts 8, nr 10 (22.09.2018): 411. http://dx.doi.org/10.3390/catal8100411.

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Developing efficient catalyst for CO oxidation at low-temperature is crucial in various industrial and environmental remediation applications. Herein, we present a versatile approach for controlled synthesis of carbon nitride nanowires (CN NWs) doped with palladium and copper (Pd/Cu/CN NWs) for CO oxidation reactions. This is based on the polymerization of melamine by nitric acid in the presence of metal-precursors followed by annealing under nitrogen. This intriguingly drove the formation of well-defined, one-dimensional nanowires architecture with a high surface area (120 m2 g−1) and doped atomically with Pd and Cu. The newly-designed Pd/Cu/CN NWs fully converted CO to CO2 at 149 °C, that was substantially more active than that of Pd/CN NWs (283 °C) and Cu/CN NWs (329 °C). Moreover, Pd/Cu/CN NWs fully reserved their initial CO oxidation activity after 20 h. This is mainly attributed to the combination between the unique catalytic properties of Pd/Cu and outstanding physicochemical properties of CN NWs, which tune the adsorption energies of CO reactant and reaction product during the CO oxidation reaction. The as-developed method may open new frontiers on using CN NWs supported various noble metals for CO oxidation reaction.

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Feitelberg, Alan S., i Sanjay M. Correa. "The Role of Carbon Monoxide in NO2 Plume Formation". Journal of Engineering for Gas Turbines and Power 122, nr 2 (3.01.2000): 287–92. http://dx.doi.org/10.1115/1.483215.

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Through a series of computational studies, carbon monoxide has been identified as an important promoter of NO oxidation to NO2 in combustion turbine exhaust gas at intermediate temperatures (450 to 750°C). NO2 formation is accompanied by enhanced CO burnout at these temperatures. Perfectly stirred reactor and plug flow reactor calculations indicate that concentrations of CO as low as 50 ppmv in exhaust gas containing 25 ppmv NO can result in the conversion of 50 percent of the NO to NO2 in less than 1 s. NO2 concentrations as low as 15 ppmv can result in visible, yellow-brown plumes from large diameter exhaust stacks. If NO2 plumes are to be prevented, then designers of gas turbines and heat recovery steam generators need to be aware of the relationships between time, temperature, and composition which cause NO2 to form in exhaust gas. Reaction path analysis indicates that the mutually promoted oxidation of CO and NO occurs through a self-propagating, three-step chain reaction mechanism. CO is oxidized by OH CO+OH→CO2+H, while NO is oxidized by HO2:NO+HO2→NO2+OH. In a narrow temperature range, the H-atom produced by the first reaction can react with O2 in a three body reaction to yield the hydroperoxy radical needed in the second reaction: H+O2+M→HO2+M, where M is any third body. The observed net reaction is CO+O2+NO→CO2+NO2, which occurs stoichiometrically at temperatures below about 550°C. As the temperature increases, additional reaction pathways become available for H, HO2, and OH which remove these radicals from the chain and eventually completely decouple the oxidation of CO from NO. An abbreviated set of elementary chemical reactions, including 15 species and 33 reactions, has been developed to model CO-enhanced oxidation of NO to NO2. This reaction set was derived from a larger reaction set with more than 50 species and 230 elementary chemical reactions, and was validated by comparison of PSR and PFR calculations using the two sets. [S0742-4795(00)01402-2]

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Dosa, Melodj, Miguel Jose Marin-Figueredo, Enrico Sartoretti, Chiara Novara, Fabrizio Giorgis, Samir Bensaid, Debora Fino, Nunzio Russo i Marco Piumetti. "Cerium-Copper Oxides Synthesized in a Multi-Inlet Vortex Reactor as Effective Nanocatalysts for CO and Ethene Oxidation Reactions". Catalysts 12, nr 4 (23.03.2022): 364. http://dx.doi.org/10.3390/catal12040364.

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In this study, a set of CuCeOx catalysts was prepared via the coprecipitation method using a Multi-Inlet Vortex Reactor: the Cu wt.% content is 5, 10, 20, 30 and 60. Moreover, pure CeO2 and CuO were synthesized for comparison purposes. The physico-chemical properties of this set of samples were investigated by complementary techniques, e.g., XRD, N2 physisorption at −196 °C, Scanning Electron Microscopy, XPS, FT-IR, Raman spectroscopy and H2-TPR. Then, the CuCeOx catalysts were tested for the CO and ethene oxidation reactions. As a whole, all the prepared samples presented good catalytic performances towards the CO oxidation reaction (1000 ppm CO, 10 vol.% O2/N2): the most promising catalyst was the 20%CuCeOx (complete CO conversion at 125 °C), which exhibited a long-term thermal stability. Similarly, the oxidative activity of the catalysts were evaluated using a gaseous mixture containing 500 ppm C2H4, 10 vol.% O2/N2. Accordingly, for the ethene oxidation reaction, the 20%CuCeOx catalyst evidenced the best catalytic properties. The elevated catalytic activity towards CO and ethene oxidation was mainly ascribed to synergistic interactions between CeO2 and CuO phases, as well as to the high amount of surface-chemisorbed oxygen species and structural defects.

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Lin, Ken-Huang, Shin-Pon Ju, Jia-Yun Li i Hsin-Tsung Chen. "The CO oxidation mechanism on the W(111) surface and the W helical nanowire investigated by the density functional theory calculation". Physical Chemistry Chemical Physics 18, nr 4 (2016): 3322–30. http://dx.doi.org/10.1039/c5cp05681k.

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Mishchenko, Denis D., Zakhar S. Vinokurov, Tatyana N. Afonasenko, Andrey A. Saraev, Mikhail N. Simonov, Evgeny Yu Gerasimov i Olga A. Bulavchenko. "Insights into the Contribution of Oxidation-Reduction Pretreatment for Mn0.2Zr0.8O2−δ Catalyst of CO Oxidation Reaction". Materials 16, nr 9 (2.05.2023): 3508. http://dx.doi.org/10.3390/ma16093508.

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A Mn0.2Zr0.8O2−δ mixed oxide catalyst was synthesized via the co-precipitation method and studied in a CO oxidation reaction after different redox pretreatments. The surface and structural properties of the catalyst were studied before and after the pretreatment using XRD, XANES, XPS, and TEM techniques. Operando XRD was used to monitor the changes in the crystal structure under pretreatment and reaction conditions. The catalytic properties were found to depend on the activation procedure: reducing the CO atmosphere at 400–600 °C and the reaction mixture (O2 excess) or oxidative O2 atmosphere at 250–400 °C. A maximum catalytic effect characterized by decreasing T50 from 193 to 171 °C was observed after a reduction at 400 °C and further oxidation in the CO/O2 reaction mixture was observed at 250 °C. Operando XRD showed a reversible reduction-oxidation of Mn cations in the volume of Mn0.2Zr0.8O2−δ solid solution. XPS and TEM detected the segregation of manganese cations on the surface of the mixed oxide. TEM showed that Mn-rich regions have a structure of MnO2. The pretreatment caused the partial decomposition of the Mn0.2Zr0.8O2−δ solid solution and the formation of surface Mn-rich areas that are active in catalytic CO oxidation. In this work it was shown that the introduction of oxidation-reduction pretreatment cycles leads to an increase in catalytic activity due to changes in the origin of active states.

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Bzovska i Mryglod. "Chemical oscillations in catalytic CO oxidation reaction". Condensed Matter Physics 13, nr 3 (2010): 34801. http://dx.doi.org/10.5488/cmp.13.34801.

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Arán-Ais, Rosa M., Francisco J. Vidal-Iglesias, Manuel J. S. Farias, José Solla-Gullón, Vicente Montiel, Enrique Herrero i Juan M. Feliu. "Understanding CO oxidation reaction on platinum nanoparticles". Journal of Electroanalytical Chemistry 793 (maj 2017): 126–36. http://dx.doi.org/10.1016/j.jelechem.2016.09.031.

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Oleksenko, Lyudmila, George Fedorenko, Igor Matushko, Nelly Maksymovych i Inna Vasylenko. "Perspectives for usage of adsorption semiconductor sensors based on Pd/SnO2 in environmental monitoring of carbon monoxide and methane emission". E3S Web of Conferences 280 (2021): 06003. http://dx.doi.org/10.1051/e3sconf/202128006003.

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Nanosized semiconductor sensor materials based on SnO2 with different palladium contents were obtained via zol-gel technology with the use of ethylene glycol and hydrate of tin (VI) chloride as precursors. Morphology and phase composition of nanosized sensor materials were studied by X-ray diffraction and TEM methods. Catalytic activities of the Pd/SnO2 nanomaterials in the reaction of H2 and CO oxidation were investigated. Adsorption semiconductor sensors based on Pd/SnO2 nanomaterials were made by their calcination up to 620 0C in air and the sensors were found to be highly sensitive to presence of CO and CH4 in air ambient. Higher responses to CO of Pd-containing sensors in comparison with their responses to CH4 were confirmed by higher reaction activity of CO in catalytic oxidation reaction. Differences in sensitive properties of the sensors to methane and carbon monoxide were explained by features of the catalytic reactions of methane and carbon monoxide oxidation occurring on surfaces of the gas sensitive layers of the sensors.

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Rozprawy doktorskie na temat "CO oxidation reaction"

Dhanasekaran, Venkatesan. "Oxide supported Au-Pd nanoparticles for CO oxidation reaction". Thesis, Sorbonne Paris Cité, 2017. https://theses.md.univ-paris-diderot.fr/DHANASEKARAN_Venkatesan_1_va_20170629.pdf.

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Les nanoparticules (NPs) bimétalliques Au-Pd ont été étudiées pour leur activité catalytique dans la réaction d'oxydation du CO. La technique de préparation, la taille et la composition des nanoparticules ont un grand impact sur le comportement catalytique du système. Ici, des nanoparticules de 3 et 5nm de diamètre Au1-xPdx (x = 0, 0.25, 0.5, 0.75, 1) ont été utilisées pour étudier l'effet de la taille et de la composition. Les échantillons ont été synthétisés par nano-lithographie à base de micelles, technique bien adaptée pour obtenir des particules ayant une distribution en taille étroite. Afin d’obtenir une répartition homogène des micelles chargées en ions métalliques sur des substrats de SiO2/Si(001), nous avons eu recours à la méthode de « spin-coating » et obtenu une organisation quasi-hexagonales des micelles observable en SEM. Un plasma d'oxygène ou d'hydrogène a été utilisé pour éliminer le polymère, réduire les ions métalliques et permettre la formation de nanoparticules. Nous avons entrepris une approche systématique pour étudier l'effet du plasma sur la structure et la morphologie des NPs à l'aide des techniques de diffusion des rayons X. L'oxydation et l'activité catalytique des NPs Au1-xPdx pour l'oxydation du CO ont été étudiées à 300 °C et 0.5 bar dans le réacteur à flux XCAT disponible sur la ligne de lumière SixS du Synchrotron SOLEIL, France. Les mesures de l'activité d'oxydation du CO ont montré que les NPs préparées en utilisant le plasma d'oxygène présentent un taux de conversion en CO2 plus élevé que les NPs préparées à l'aide de plasma d'hydrogène pour une composition donnée. Les nanoparticules de Pd préparées avec du plasma d'O2 se sont révélées être le catalyseur le plus actif : aucun effet synergique n'a été observé pour les nanoparticules bimétalliques pour la réaction d'oxydation du CO
Au-Pd bimetallic nanoparticles (NPs) have been studied for their catalytic activity in CO oxidation reaction. The preparation technique, size and composition of the nanoparticles have great impact on the catalytic behaviour of the system. Here, 3 and 5nm diameter Au1-xPdx (x = 0, 0.25, 0.5, 0.75, 1) nanoparticles were employed to study the effect of size and composition. The samples were synthesized by micelle nanolithography, a technique well adapted to yield narrow size distribution of nanoparticles. To achieve monodisperse metal-loaded micelles on SiO2/Si(001) substrates we employed spin-coating and observe quasi-hexagonal ordered micelles in SEM. Oxygen or hydrogen plasma were used to remove the polymer, reduce the metal ions and enable nanoparticle formation. We made a systematic approach to study the effect of plasma on the structure and morphology of the NPs by means of surface x-ray scattering techniques. The oxidation behavior and CO oxidation activity of the Au1-xPdx NPs were studied at 300°C and 0.5 bar in the flow reactor XCAT available at the SixS Beamline, Synchrotron SOLEIL, France. The CO oxidation activity measurements showed that the NPs prepared using the oxygen plasma present higher CO2 conversion rate than the NPs prepared using hydrogen plasma for a given composition. The Pd nanoparticles prepared using O2 plasma were found to be the most active catalyst: no synergetic effects were observed for bimetallic nanoparticles for the CO oxidation reaction

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Balakrishnan, Nianthrini. "Theoretical Studies of Co Based Catalysts on CO Hydrogenation and Oxidation". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4434.

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CO hydrogenation and CO oxidation are two important processes addressing the energy and environmental issues of great interest. Both processes are carried out using metallic catalysts. The objective of this dissertation is to study the catalytic processes that govern these two reactions from a molecular perspective using quantum mechanical calculations. Density Functional Theory (DFT) has proven to be a valuable tool to study adsorption, dissociation, chain growth, reaction pathways etc., on well-defined surfaces. DFT was used to study the CO reduction reactions on promoted cobalt catalyst surfaces and CO oxidation mechanisms on cobalt surfaces. CO hydrogenation via Fischer-Tropsch Synthesis (FTS) is a process used to produce liquid fuels from synthesis gas. The economics of the Fischer-Tropsch process strongly depends on the performance of the catalyst used. The desired properties of a catalyst include selectivity towards middle distillate products such as diesel and jet fuel, higher activity and longer catalyst life. Catalysts are often modified by adding promoters to obtain these desirable properties. Promoters can influence the reaction pathways, reducibility, dispersion, activity and selectivity. In FTS, understanding the effect of promoters in the molecular scale would help in tailoring catalysts with higher activity and desired selectivity. Preventing deactivation of catalyst is important in FTS to increase the catalyst life. Deactivation of Co catalyst can occur by reoxidation, C deposition, sintering, formation of cobalt-support compounds etc. Designing catalyst with resistance to deactivation by the use of promoters is explored in this dissertation. The influence of promoters on the initiation pathways of CO hydrogenation is also explored as a first step towards determining the selectivity of promoted catalyst. The influence of Pt promoter on O removal from the surface of Co catalyst showed that Pt promoter reduced the activation barrier for the removal of O on both flat and stepped Co surfaces. An approximate kinetic model was developed and a volcano plot was established. The turn-over frequency (TOF) calculated based on the activation barriers showed that Pt promoted Co surface had a higher rate than unpromoted Co surface. The effect of Pt and Ru promoters on various pathways of C deposition on Co catalyst was studied to gain a mechanistic understanding. The promoters did not affect the subsurface C formation but they increased the barriers for C-C and C-C-C formation and also decreased the barriers for C-H formation. The promoters also influence the stabilities of C compounds on the Co surface suggesting that Pt and Ru promoters would decrease C deposition on Co catalysts. The effect of Pt promoter on unassisted and H-assisted CO activation pathways on Co catalyst was studied. Pt promoted Co surface followed H-assisted CO activation. Pt promoter decreased the activation barriers for CO activation pathways on Co catalyst thereby increasing the activity of Co catalyst. CO oxidation is a process used to prevent poisoning of fuel cell catalysts and reduce pollution of the atmosphere through exhaust gases containing CO. Expensive catalysts like Pt are widely used for CO oxidation which significantly increases the cost of the process and hence it is necessary to search for alternative lower cost catalysts. Understanding the mechanism of a reaction is the first step towards designing better and efficient catalyst. DFT is helpful in determining the basic mechanism and intermediates of reactions. The mechanism of CO oxidation on CoO catalyst was explored. Four possible mechanisms for CO oxidation on CoO catalyst were studied to determine the most likely mechanism. The mechanism was found to be a two-step process with activation barrier for formation of CO2 larger than the barrier for formation of the intermediate species.

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Davó-Quiñonero, Arantxa. "Copper-based catalysts for the Preferential Oxidation of CO in H2-rich streams (CO-PROX reaction)". Doctoral thesis, Universidad de Alicante, 2019. http://hdl.handle.net/10045/98737.

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The Preferential CO Oxidation (CO-PROX) is a promising catalytic strategy to remove CO residual content from H2-rich streams. Mixed copper and cerium oxide catalysts are materials that display an excellent performance towards COPROX reaction by means of synergistic interaction the copper and cerium-rich phases. Alternatively, mixed manganese oxides are proposed as active supports with very positive catalytic features when these are loaded with copper species. This Project Thesis comprises a detailed study on the implementation of copper oxide – manganese oxide catalysts in CO-PROX reaction and the establishment of a critical comparison with regards to the consolidated cerium-based catalysts.

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Kim, Sang Hoon. "Study of reaction mechanisms on single crystal surfaces with scanning tunneling microscopy". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2003. http://dx.doi.org/10.18452/14884.

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Ziel dieser Arbeit war, die Rastertunnelmikroskopie, die bereits zur Aufklärung von einfachen Reaktionsmechanismen eingesetzt wurde, für em kompliziertere Reaktionen anzuwenden. Die Oxidation von CO auf Pd(111) und auf einem RuO2-Film auf Ru(0001) wurde untersucht. Strukturelle Analysen ergeben mikroskopische Verteilungen der Adsorbate in den Überstrukturen von O und CO auf Pd(111) und RuO2. Dynamische und quantitative Analysen der Reaktionen liefern die Kinetik und die Mechanismen der Reaktionen direkt auf der mikroskopischen Ebene. O-Atome auf Pd(111) sind bei mittleren Bedeckungsgraden (0.10< theta mathrm O 135 K beweglich. Die Aktivierungsenergie der Diffusion (E * mathrm diff ) beträgt 0.54 pm 0.08 eV, der präexponentielle Faktor der Sprünge Gamma mathrm o beträgt 10 16 pm 3 s -1. Bei niedrigen Bedeckungen (theta mathrm CO sim 0) sind die CO-Moleküle auf Pd(111) schon bei T mathrm sample = 60 K sehr beweglich. Wenn man einen präexponentiellen Faktor von Gamma mathrm o = 10 13 s -1 annimmt, ergibt sich für E * mathrm diff von CO ein Wert von 0.15 eV. Adsorbiert CO auf der (2 times2) -O-Überstruktur bei T mathrm sample > 130 K, kommt es mit steigendem Bedeckungsgrad von CO zu Phasenübergängen, zunächst in eine ( sqrt 3 times Sqrt 3 ) R30 circ -O-Struktur, dann in eine (2 times1)-Struktur. Während der Phasenübergänge nimmt die Mobilität der O-Atome zu, was sich in einer Abnahme der E* mathrm diff um 10 bis 20 % (unter der Annahme von Gamma mathrm o = 10 16 s -1) im Vergleich zu einer CO-freien Oberfläche niederschlägt. Am Ende der Phasenübergänge entstehen aus einer fast völlig ungeordneten (O+CO)-Phase viele kleine (2 times1)-Inseln, die sich zu grösseren Inseln zusammenlegen. Die (2 times1)-Inseln sind bereits bei T mathrm sample = 136 K sehr reaktiv. Die quantitative Analyse der Abreaktion der (2 times1)-Inseln ergibt, dass die Reaktionsrate proportional zur Inselfläche und nicht zur Randlänge ist. Die Reaktionsordnung bezüglich theta mathrm(2 times1) ist sim 1. Unter der Annahme eines Vorfaktors k mathrm o von 10 13 s -1 wurde für diese Reaktion ein E* mathrm reac von 0.41 eV abgeschätzt. Für eine CO-Adsorption auf der (2 times2)-O-Überstruktur bei T mathrm sample < 130 K kommt es nicht zu einem Phasenübergang, sondern CO adsorbiert auf der (2 times2)-O-Struktur. Der RuO2-Film wurde bei Temperaturen zwischen 650 und 900 K auf der Ru(0001)-Probe aufgewachsen. Die Morphologie des Oxidfilms hängt stark von der Temperatur der Probe während des Wachstums Tprep ab. Bei Tprep sim 650 K ist die Morphologie überwiegend kinetisch bestimmt. Mit steigendener Temperatur bis Tprep = 900 K werden thermodynamische Effekte immer wichtiger. Die Dicke der Oxidschicht hängt nicht von Tprep ab und beträgt 7 AA bis 15 AA, was 2 bis 5 (Ru-O)-Monolagen entspricht. Die thermodynamische Stabilität der Morphologie ergibt sich aus Experimenten, in denen die Oxidschicht durch Heizen auf verschiedene Temperaturen partiell verdampft wurde. Der Film dampft nicht lageweise ab, sondern es entstehen Löcher in der ansonsten unverdampften Oxidschicht. Die Löcher haben eine charakteristische Form. Sie bilden Parallelogramme oder Rechtecke mit einer langen Achse in [001]-Richtung. Die Oberflächenenergie gamma 001 der einen Flanke der Löcher ist 2 bis 5 mal grösser als gamma bar110 der anderen Flanke. Beim Verdampfen des Films verbleiben die freigesetzten Ru-Atome des Oxids auf dem Substrat. Sie bilden dort eine komplizierte Morphologie von hexagonalen und runden Inseln. Die mikroskopischen Beobachtungen der chemischen Prozesse auf dem Film bestätigen die auf den makroskopischen Untersuchungen basierenden Modelle. Ein neuer Befund ist, dass die CO-Moleküle bei Raumtemperatur auf den Rulf -Reihen stabil adsorbieren, sobald die Ruzf -Reihen vollständig mit CO bedeckt sind. Der maximale Bedeckungsgrad theta mathrm CO1f ist 0.5, die COlf-Moleküle bilden lokal geordnete (2times1)-, c(2times2)- und (1times1)-Überstrukturen. Allerdings kommt es bei theta mathrm CO1f sim 0.5 zu einer langsamen Desorption. Wenn man ein k mathrm o von 10 16 s -1 annimmt, lässt sich ein E * mathrm des von 1.00 eV abschätzen. Unter der Annahme von Gamma mathrm o und k mathrm o von 10 13 s -1 lassen sich E* mathrm diff -Werte für O und CO zwischen 0.89 und 0.93 eV abschätzen, und für die Reaktion zwischen COlf und Olf ein Wert von E* mathrm reac sim 0.87 eV. Die Reaktionen zwischen Ozf und COlf, zwischen Olf und COzf sowie zwischen Olf und COlf verlaufen überwiegend statistisch. Manchmal wird eine leicht bevorzugte Reaktion quer zu den Rulf - und Ruzf -Reihen beobachtet. Unter steady-state-Bedingungen kann CO bei genügend grossem Partialdruck auf der Oberfläche adsorbieren. Unter steady-state-Bedingungen werden die gleichen COlf-Überstrukturen beobachtet wie in einer CO-Atmosphäre oder bei der Titration mit CO. Bei massiver Dosierung der Oxidoberfläche mit Oz und CO (sim 100 L) werden weisse Flecken beobachtet, die COlf ähnlich sind. Allerdings reagieren diese weder mit Oz noch mit CO, was auf einen anderen chemischen Zustand der RuO2-Oberfläche als den sauberen Zustand hinweist.
Scanning Tunneling Microscopy has already been established as a tool for the investigation of simple reaction mechanisms. The aim of this thesis was to apply this technique to study emmore complicated reactions. The oxidation of CO on Pd(111) and on a RuO2 film grown on Ru(0001) was investigated. Structural analyses of the O, CO and (CO+O) adlayers on Pd(111) and on RuO2 reveal the microscopic distributions of the adsorbates on the surfaces. Dynamic and quantitative analyses of the reactions yield the reaction kinetics and the reaction mechanisms in a direct way at the microscopic level. O atoms on Pd(111) at intermediate coverages (0.10

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Siriwardane, Upali. "Systematic syntheses of iron-triad (Fe,Ru,Os) tetranuclear clusters by redox condensation reactions of [Ru(3);CO(11)) and [Os(3);CO(11)] trinuclear carbonylates; co-crystallization of ruthenium-osmium clusters /". The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487264603216477.

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Gottfried, Jörg Michael. "CO oxidation over gold adsorption and reaction of oxygen, carbon monoxide, and carbon dioxide on an Au(110)-(1x2) surface /". [S.l. : s.n.], 2003. http://www.diss.fu-berlin.de/2003/133/index.html.

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Freitas, Kênia da Silva. "Eletrocatalisadores de ligas de platina dispersos em substratos de óxidos para a reação de oxidação de hidrogênio puro e na presença de CO". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-25082009-164210/.

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Neste trabalho são apresentados resultados dos estudos da reação de oxidação de hidrogênio puro realizados em eletrodos rotatório em camada ultrafina porosa e na presença de CO em células a combustível utilizando catalisadores formados por Pt dispersas em substratos de óxidos, tais como, Pt/RuO 2 -C, Pt/RhO 2 -C, Pt/WO 3 -C e em Pt/WC-C. As reações foram também estudadas em suporte puro, como, RhO 2 /C e WC/C em diferentes proporções atômicas. Este estudo teve como finalidade estudar as propriedades catalíticas destes materiais visando elucidar os mecanismos da reação de oxidação de hidrogênio (ROH) sobre estes catalisadores dispersos, possibilitando a obtenção de parâmetros cinéticos das reações. Em conjunto com as medidas eletroquímicas, foram realizados estudos sobre as propriedades eletrônicas e estruturais destes catalisadores, o que possibilita relacionar suas propriedades eletrônicas e estruturais com a cinética da HOR. Observou-se que a presença dos óxidos de Ru, Rh e WO 3 favorecem a diminuição do grau de recobrimento da Pt por CO, deixando mais sítios disponíveis a ROH, em consequência do esvaziamento da banda 5d da Pt, o que diminui a retro-doação de elétrons da Pt ao CO, diminuindo a força da ligação Pt-CO. Como observado, essas modificação eletrônicas observadas nos espectros de XANES não induziram a nenhuma mudança perceptível na cinética ou no mecanismo reacional. Para quase todos os catalisadores, a tolerância ao CO pode ser explicada tanto em termos do mecanismo eletrônico como do bifuncional evidenciado pela formação de CO 2 nas medidas de EMS.
This work shows results of studies of the hydrogen oxidation reaction (HOR) pure in rotation in ultra porous layer and in the presence of CO in the fuel cell to the electrocatalysts of Pt alloy dispersed on oxide substrates such Pt/RuO 2 -C, Pt/RhO 2 -C, Pt/WO 3 -C, Pt/WC-C and pure materials, as RhO 2 /C and WC. The study of the catalytic properties of these materials to elucidate the mechanisms of hydrogen oxidation reaction on these dispersed catalysts, allowing the collection of kinetic parameters of reactions. Together with the electrochemical measurements were carried out studies on the structural and electronic properties of these catalysts, which allow relating their structural and electronic properties with the kinetics of the HOR. It was observed that the presence of oxides of Ru, Rh and WO 3 encourage the reduction of the degree of coating of Pt by CO, leaving more sites available to ROH, as a consequence of emptying of the Pt 5d band, which reduces the backdonation of electrons from Pt to CO by reducing the strength of Pt-CO binding. As noted, these changes observed in electronic spectra of XANES not led to any perceptible change in the kinetics or the reaction mechanism. For almost all catalysts, the CO tolerance can be explained in terms of the electronic effect and the bifunctional mechanism evidenced by the formation of CO 2 in the EMS.

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Herrera, Delgado Karla [Verfasser], i O. [Akademischer Betreuer] Deutschmann. "Surface Reaction Kinetics for Oxidation and Reforming of H2, CO, and CH4 over Nickel-based Catalysts / Karla Herrera Delgado. Betreuer: O. Deutschmann". Karlsruhe : KIT-Bibliothek, 2014. http://d-nb.info/1056955864/34.

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Schilling, Christian Michael [Verfasser], Christian [Akademischer Betreuer] Hess, Rolf [Akademischer Betreuer] Schäfer i Rolf Jürgen [Akademischer Betreuer] Behm. "Operando Spectroscopy and DFT Modeling of Gold/Ceria Catalysts for CO Oxidation and Water-Gas Shift Reaction / Christian Michael Schilling ; Christian Hess, Rolf Schäfer, Rolf Jürgen Behm". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1163013528/34.

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Wang, Tongyu [Verfasser], Karsten [Akademischer Betreuer] Reuter i Sebastian [Akademischer Betreuer] Günther. "Shape and Catalytic Mechanism of RuO2 Particles at CO Oxidation Reaction Conditions: First-Principles Based Multi-Scale Modeling / Tongyu Wang. Betreuer: Karsten Reuter. Gutachter: Karsten Reuter ; Sebastian Günther". München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1079001883/34.

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Książki na temat "CO oxidation reaction"

Field Applications of in Situ Remediation Technologies: Permeable Reactive Barriers Prb, and Chemical Oxidation Co. Diane Pub Co, 1999.

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Części książek na temat "CO oxidation reaction"

Piccolo, L., C. Becker i C. R. Henry. "Kinetic modeling of the CO oxidation reaction on supported metal clusters". W The European Physical Journal D, 415–19. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-88188-6_82.

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Levec, Janez. "Opportunities in Catalytic Reaction Engineering. Examples of Heterogeneous Catalysis in Water Remediation and Preferential CO Oxidation". W Chemical Engineering, 103–24. Chichester, UK: John Wiley & Sons, Ltd, 2005. http://dx.doi.org/10.1002/0470025018.ch5.

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Stanković, Miroslav, i Aleksandra Milutinović-Nikolić. "Nickel Catalysts on Porous Ceramic Supports for the Reaction of Partial Oxidation of Propane to CO and H2". W Proceedings of the IV Advanced Ceramics and Applications Conference, 401–16. Paris: Atlantis Press, 2017. http://dx.doi.org/10.2991/978-94-6239-213-7_28.

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Coulstont, George W., i Gary L. Haller. "Is There a Distribution of Transition State Energies in the Reaction Coordinate of CO Oxidation on Pt Foil?" W Fundamental Aspects of Heterogeneous Catalysis Studied by Particle Beams, 145–50. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-5964-7_13.

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Eid, Kamel, Sarah Mohammed Hailan, Yasseen S. Ibrahim, Belal Salah i Aboubakr M. Abdullah. "CHAPTER 1. Recent Advances in the Controlled Design of One-dimensional Carbon Nitrides for Thermal CO Oxidation Reaction". W Nanoscience & Nanotechnology Series, 1–37. Cambridge: Royal Society of Chemistry, 2021. http://dx.doi.org/10.1039/9781839164606-00001.

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Šmíd, Bretislav, Toshiyuki Mori, M. Takahashi, Ding Rong Ou, V. Matolín i Iva Matolínova. "Fabrication and Microanalysis of Nano-Structured CuO_X-CeO₂ Catalysts for CO Oxidation Reaction". W THERMEC 2006 Supplement, 261–66. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-429-4.261.

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Eisenberg, R., i C. Kubiak. "Oxidation and Reduction of CO". W Inorganic Reactions and Methods, 381–82. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch159.

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Destro, Priscila. "AuCu Nanoparticles Applied on Heterogeneous Catalysis: Studies About the Stability of Nanoparticles Under Redox Pre-treatments and Application in CO Oxidation Reaction". W Colloidal Nanoparticles for Heterogeneous Catalysis, 41–71. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-03550-1_3.

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Chabal, Y. J., S. B. Christman, V. A. Burrows, N. A. Collins i S. Sundaresan. "Self-sustained Kinetic Oscillations in the Catalytic CO Oxidation on Platinum". W Kinetics of Interface Reactions, 285–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-72675-0_24.

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"Oxidation". W Biocatalysis in Organic Synthesis: The Retrosynthesis Approach, 113–78. The Royal Society of Chemistry, 2018. http://dx.doi.org/10.1039/bk9781782625308-00113.

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This chapter complements the previous chapter and covers enzyme classes that catalyse oxidation reactions, including ketoreductases, enoate reductases, oxidases, haloperoxidases, P450 monooxygenases, Baeyer–Villiger monooxygenases, dioxygenases, lipooxygenases, and halogenases. The chapter is divided into separate sections, each detailing the oxidation of a specific functional group, including alkanes, alkenes, alcohols, aldehydes, ketones, amines, imines, sulfides, sulfoxides and the oxidative dealkylation of ethers. Each section begins with a review of chemical methods of carrying out each transformation, followed by a description of the enzyme classes that are capable of catalysing the transformation. The substrate scope of each enzyme class, including its chemo-, regio- and stereoselectivity, is discussed and a general mechanism for the enzyme-catalysed reaction is presented. Where appropriate, strategies for co-factor recycling are also included. This should give the reader a good understanding of when and how to carry out oxidations using enzymes.

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Streszczenia konferencji na temat "CO oxidation reaction"

Feitelberg, Alan S., i Sanjay M. Correa. "The Role of Carbon Monoxide in NO2 Plume Formation". W ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-053.

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Through a series of computational studies, carbon monoxide has been identified as an important promoter of NO oxidation to NO2 in combustion turbine exhaust gas at intermediate temperatures (450 to 750°C). NO2 formation is accompanied by enhanced CO burnout at these temperatures. Perfectly stirred reactor and plug flow reactor calculations indicate that concentrations of CO as low as 50 ppmv in exhaust gas containing 25 ppmv NO can result in the conversion of 50% of the NO to NO2 in less than 1 second. NO2 concentrations as low as 15 ppmv can result in visible, yellow-brown plumes from large diameter exhaust stacks. If NO2 plumes are to be prevented, then designers of gas turbines and heat recovery steam generators need to be aware of the relationships between time, temperature, and composition which cause NO2 to form in exhaust gas. Reaction path analysis indicates that the mutually promoted oxidation of CO and NO occurs through a self-propagating, three-step chain reaction mechanism. CO is oxidized by OH, (R2)CO+OH→CO2+Hwhile NO is oxidized by HO2:(R23)NO+HO2→NO2+OHIn a narrow temperature range, the H-atom produced by R2 can react with O2 in a three body reaction to yield the hydroperoxy radical needed in R23:(R9)H+O2+M→HO2+Mwhere M is any third body. The observed net reaction isCO+O2+NO→CO2+NO2which occurs stoichiometrically at temperatures below about 550°C. As the temperature increases, additional reaction pathways become available for H, HO2, and OH which remove these radicals from the chain and eventually completely decouple the oxidation of CO from NO. An abbreviated set of elementary chemical reactions, including 15 species and 33 reactions, has been developed to model CO-enhanced oxidation of NO to NO2. This reaction set was derived from a larger reaction set with more than 50 species and 230 elementary chemical reactions, and was validated by comparison of PSR and PFR calculations using the two sets.

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Le Cong, Tanh, i Philippe Dagaut. "Kinetics of Natural Gas, Natural Gas/Syngas Mixtures Oxidation and Effect of Burnt Gas Recirculation: Experimental and Detailed Modeling". W ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27146.

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The oxidation of methane-based fuels was studied experimentally in a fused silica jet-stirred reactor (JSR) operating at 1–10 atm, over the temperature range 900-1400 K, from fuel-lean to fuel-rich conditions. Similar experiments were performed in presence of carbon dioxide or syngas (CO/H2). A previously proposed kinetic reaction mechanism updated for modeling the oxidation of hydrogen, CO, methane, methanol, formaldehyde, and natural gas over a wide range of conditions including JSR, flame, shock tube, and plug flow reactor was used. A detailed chemical kinetic modeling of the present experiments was performed yielding a good agreement between the data and the modeling. Literature burning velocities and ignition delays were also modeled. Reaction paths analyses were used to delineate the important reactions influencing the kinetic of oxidation of the fuels in presence of variable amounts of CO2. The kinetic reaction scheme proposed helps determining the effect of the additives on the oxidation of methane.

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Burra, K. G., i A. K. Gupta. "Co-Processing of Municipal Solid Waste With Gypsum Waste for Enhanced Product Recovery". W ASME 2022 Power Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/power2022-85550.

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Abstract With growing generation of municipal solid wastes, development of sustainable disposal techniques is essential for effective utilization of these resources. While waste-to-energy (WtE) facilities provide energy recovery from these wastes, the low relative value of energy makes it unattractive. Simultaneously, high oxidation environment in these facilities also means losing significantly valuable resources such as metals/mineral in the form of their oxides and forming pollutant flue gases and fly-ash. Alternative pathways in waste-to-energy involve designing variable oxygen staging to effectively limit oxidation to only carbonaceous materials while minimizing high oxidation state products of metals. In such operating conditions, formation of char from the MSW components is thermodynamically favored and effective utilization of this resource in-situ can be valuable to improve the reactor operability. In this study, we investigated the feasibility of utilizing waste gypsum from construction/demolition sector to co-process in WtE process. Thermogravimetric analysis (TGA) with FTIR analysis of evolved gas was utilized to understand the operation conditions for such a co-processing and the formation of evolved gas products such as CO2, CO and SO2. Char formed from pyrolysis of waste tires was investigated to examine its reactions with gypsum. Char was found to be reduced by reacting with the anhydrous gypsum at temperatures beyond 850 °C. These studies also include the effect of oxidation potential of the purge gas on this reaction which was carried out by introducing 4.8% O2 into the TGA purge gas to understand its effect on the reaction of gypsum with the char in comparison to char oxidation.

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Utaka, Toshimasa, Koichi Eguchi, Koshi Sekizawa i Kazunari Sasaki. "Removal of CO from Reformed Fuel by Shift Reaction and Selective Oxidation". W CEC/SAE Spring Fuels & Lubricants Meeting & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-2008.

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TOLSTOV, G. I., I. A. MEDVEDKOV, D. P. PORFLRIEV, M. V. ZAGIDULLIN, A. M. MEBEL i V. N. AZYAZOV. "MODELING OF THE COMPLETE MECHANISM OF OXIDATION OF PHENYL RADICAL UNDER COMBUSTION CONDITIONS". W 9th International Symposium on Nonequilibrium Processes, Plasma, Combustion, and Atmospheric Phenomena. TORUS PRESS, 2020. http://dx.doi.org/10.30826/nepcap9b-08.

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Quantum chemical calculations, computational fluid dynamics (CFD) simulations, and isothermal approximation were applied for the interpretation of experimental measurements of the reaction of C6H5+O2 in the high-temperature microreactor and of the pressure drop in the flow tube of the reactor. Applying isothermal approximation allows the derivation of analytical relationships between the kinetic, gas flow, and geometrical parameters of the microreactor which, along with CFD simulations, accurately predict the experimental observations. The analysis showed that at the first stage, mainly C6H5O is formed in reaction C6H5+O2→C6H5O+O and C5H5 in reaction C6H5+O2→C5H5+CO2. С6Н5О decomposes either with the formation of C5H5 in reaction C6H5O→C5H5+CO or into other components. The decrease in С5Н5 in secondary reactions is insignificant. It has been demonstrated that CFD modeling is a powerful tool for understanding the complex physical and chemical processes inside a microreactor.

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Shi, Yixiang, Won Yong Lee i Ahmed F. Ghoniem. "Elementary Reaction Models for CO Electrochemical Oxidation on an Ni/YSZ Patterned Anode". W ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33205.

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Analysis of recent experimental impedance spectra and polarization curves of nickel/yttria-stabilized zirconia (Ni/YSZ) patterned anode of a solid oxide fuel cell (SOFC) are used to determine the limiting steps in CO electrochemical oxidation kinetics. A comprehensive 1D model is proposed for the prediction of the steady-state polarization curve of a patterned anode SOFC. The model incorporates gas species adsorption/desorption with surface diffusion and one of two possible charge transfer reaction steps: O charge transfer reaction [O2−(YSZ)+(Ni)+↔(YSZ)+O(Ni)+2e−], or CO charge transfer reaction [O2−(YSZ)+CO(Ni)↔(YSZ)+CO2(Ni)+2e−]. We show that the mechanism incorporating charge transfer between adsorbed CO and oxygen vacancy is able to better predict the experimental data. We estimate some of the model parameters, such as the exchange current density and charge transfer coefficient by fitting the simulation of the polarization curves to the experimental data.

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Okazaki, Hirofumi, Masayuki Taniguchi, Kenji Yamamoto i Kenichi Ochi. "Modeling of NOx and CO Reactions for Commercial Scale Pulverized Coal Firing Boilers". W ASME 2005 Power Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pwr2005-50352.

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The NOx-CO reaction model was developed for commercial scale pulverized coal firing boilers. The model was used to decide optimize combustion performance and it featured simplified sub models of NOx reduction, pyrolysis and CO oxidation. To improve combustion performance of commercial scale pulverized boilers, it is most important to predict the distribution of NOx and CO concentrations and search for the best conditions in a short time. The NOx reduction sub model was developed for both volatile and char combustion. The pyrolysis sub model was developed from a comparison of Distributed Activation Energy Model results and experimental data. The CO oxidation sub model was characterized by its consideration of the effect of hydroxide radicals. The simulation gave a lower CO oxidation rate for a long reaction time, the same as the actual result. The NOx-CO reaction model successfully analyzed NOx and CO concentration distributions of commercial scale boilers for power plants (260–1000MW).

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Gokulakrishnan, P., S. Kwon, A. J. Hamer, M. S. Klassen i R. J. Roby. "Reduced Kinetic Mechanism for Reactive Flow Simulation of Syngas/Methane Combustion at Gas Turbine Conditions". W ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90573.

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The reduced kinetic mechanism for syngas/methane developed in the present work consists of a global reaction step for fuel decomposition in which the fuel molecule breaks down into CH2O and H2. A detailed CH2O/H2/O2 elementary reaction sub-set is included as the formation of intermediate combustion radicals such as OH, H, O, HO2, and H2O2 is essential for accurate predictions of non-equilibrium phenomena such as ignition and extinction. Since the chemical kinetics of H2 and CH2O are the fundamental building blocks of any hydrocarbon oxidation, the inclusion of detailed kinetic mechanisms for CH2O and H2 oxidation enables the reduced mechanism to predict over a wide range of operating conditions provided the reaction rate parameters of fuel-decomposition reaction is optimized over those conditions. Therefore, the rate coefficients for the fuel-decomposition step are estimated and optimized for the ignition delay time measurements of CH4, H2, CH4/H2, CH4/CO and CO/H2 mixtures available in the literature over a wide range of pressures, temperatures and equivalence ratios that are relevant to gas turbine operating conditions. The optimized reduced mechanism, consisting of 15 species and around 40 reactions, is able to predict the ignition delay time and laminar flame speed measurements of CH4, H2, CH4/H2, CH4/CO and CO/H2 mixtures fairly well over a wide range conditions. The model predictions are also compared with that of GRI3.0 mechanism. The reduced kinetic mechanism predicts the ignition delay time of CH4 and CH4/H2 mixtures far better than GRI mechanism at higher pressures. To demonstrate the predictive capability of the model in reactive flow systems, the reduced mechanism was implemented in Star-CD/KINetics commercial code using a RANS turbulence model to simulate CH4/air premixed combustion in a backward facing step. The CFD model predictions of the stable species in the exhaust gas agree well with the GRI mechanism predictions in a chemical reactor network modeling by approximating the backward facing step with a series of perfectly-stirred reactor and plug-flow reactor.

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Le Cong, Tanh, i Philippe Dagaut. "Effect of Water Vapor on the Kinetics of Combustion of Hydrogen and Natural Gas: Experimental and Detailed Modeling Study". W ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50272.

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The dilution of fuels by exhausts gases (mainly CO, CO2 and H2O) affects the kinetics of combustion. This dilution is used in gas turbines and flameless combustor. It helps reducing pollutant emissions, particularly NOx. Therefore, it is useful to study the effect of such compounds on the kinetics of oxidation of fuels such as natural gas and hydrogen. The oxidation of hydrogen and that of methane were studied experimentally in a fused silica jet-stirred reactor (JSR) over the temperature range 800–1500 K, from fuel-lean to fuel-rich conditions. The experiments were repeated in presence of 10% in mole of water vapor. A detailed chemical kinetic modeling of the present experiments and of literature data (flame speed, ignition delays) was performed using a previously proposed kinetic reaction mechanism, showing good agreement between the data and this modeling. Sensitivity and reaction paths analyses were used to delineate the important reactions influencing the kinetic of oxidation of the fuels in presence of water vapor. The kinetic reaction scheme proposed helps understanding the inhibiting effect of water vapor on the oxidation of hydrogen and methane. The effect of water vapor on NOx formation under gas turbine conditions was also investigated numerically using the proposed kinetic scheme.

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Parajuli, Pradeep, Ayush Jain i Waruna D. Kulatilaka. "CO and OH Imaging in Flames Using a Single Broadband Femtosecond Laser Pulse". W ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15681.

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Abstract Carbon monoxide (CO) and hydroxyl (OH) are the two key intermediate species formed during chemical reactions inside gas turbine combustors. Spatiotemporal information and a detailed understanding of CO formation in the reaction zone are important during the combustion processes as a major part of the heat release is obtained from the oxidation of CO to CO2. Turbulent flame structures and reaction zone in different flame conditions can also be visualized through the spatial distribution profiles of OH. In the current study, both these species are excited simultaneously using a single ultrashort, broad spectral bandwidth of approximately 100-femtosecond (fs) duration laser pulse at λ = 283.8 nm. Subsequent fluorescence signals are separated through spectral filters of appropriate bandwidth and imaged using two cameras. This present study was performed in a McKenna flat-flame burner with ethylene/air as a pilot flame and non-premixed turbulent ethylene jet at the center. The partial spectral overlap of CO–X (4,0) and OH A–X (1,0) transitions are utilized for simultaneous excitation, thereby characterize the overall flame structure (via OH) and regions of oxidation reactions (via CO) in a range of flame conditions. Besides, CO and OH profiles follow the trends obtained from model predictions for a range of equivalence ratios in ethylene/air flames stabilized over the Hencken calibration burner. These results are used for obtaining quantitative calibrations of CO and OH signals. Overall, the present study extends the applicability of a single, broadband fs laser pulse for simultaneous imaging of multiple chemical species in flame.

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Raporty organizacyjne na temat "CO oxidation reaction"

Kanner, Joseph, Mark Richards, Ron Kohen i Reed Jess. Improvement of quality and nutritional value of muscle foods. United States Department of Agriculture, grudzień 2008. http://dx.doi.org/10.32747/2008.7591735.bard.

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Food is an essential to our existence but under certain conditions it could become the origin to the accumulative health damages. Technological processes as heating, chopping, mincing, grounding, promote the lipid oxidation process in muscle tissues and meat foodstuffs. Lipid oxidation occurred rapidly in turkey muscle, intermediate in duck, and slowest in chicken during frozen storage. Depletion of tocopherol during frozen storage was more rapid in turkey and duck compared to chicken. These processes developed from lipid peroxides produce many cytotoxic compounds including malondialdehyde (MDA). The muscle tissue is further oxidized in stomach conditions producing additional cytotoxic compounds. Oxidized lipids that are formed during digestion of a meal possess the potential to promote reactions that incur vascular diseases. A grape seed extract (1% of the meat weight) and butylated hydroxytoluene (0.2% of the lipid weight) were each effective at preventing formation of lipid oxidation products for 3 hours during co-incubation with cooked turkey meat in simulated gastric fluid (SGF). Polyphenols in the human diet, as an integral part of the meal prevent the generation and absorption of cytotoxic compounds and the destruction of essential nutrients, eg. antioxidants vitamins during the meal. Polyphenols act as antioxidants in the gastrointestinal tract; they scavenge free radicals and may interact with reactive carbonyls, enzymes and proteins. These all reactions results in decreasing the absorption of reactive carbonyls and possible other cytotoxic compounds into the plasma. Consumptions of diet high in fat and red meat are contributory risk factors partly due to an increase production of cytotoxic oxidized lipid products eg. MDA. However, the simultaneously consumption of polyphenols rich foods reduce these factors. Locating the biological site of action of polyphenols in the in the gastrointestinal tract may explain the paradox between the protective effect of a highly polyphenols rich diet and the low bioavailability of these molecules in human plasma. It may also explain the "French paradox" and the beneficial effect of Mediterranean and Japanese diets, in which food products with high antioxidants content such as polyphenols are consumed during the meal.

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Harold, M. P., i C. W. Conner. Kinetics and dynamics of oxidation reactions involving an adsorbed CO species. Office of Scientific and Technical Information (OSTI), lipiec 1992. http://dx.doi.org/10.2172/7088157.

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Okada, Shunji, Yoshiaki Takatani, Seijo Terada i Shinichi Ohtani. Development of a selective oxidation CO removal reactor for methanol reformate gas. Office of Scientific and Technical Information (OSTI), grudzień 1996. http://dx.doi.org/10.2172/460229.

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Harold, M. P. Kinetics and dynamics of oxidation reactions involving an adsorbed CO species on bulk and supported platinum and copper-oxide. Office of Scientific and Technical Information (OSTI), lipiec 1991. http://dx.doi.org/10.2172/6015028.

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Harold, M. P., i C. W. Conner. Kinetics and dynamics of oxidation reactions involving an adsorbed CO species. Second year annual report, January 1, 1992--December 31, 1992. Office of Scientific and Technical Information (OSTI), lipiec 1992. http://dx.doi.org/10.2172/10172964.

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Conner, Wm C., i M. Harold. Kinetics and dynamics of oxidation reactions involving adsorbed CO species on bulk supported Pt and copper oxides. Final project report, January 1, 1991--December 31, 1993. Office of Scientific and Technical Information (OSTI), luty 1995. http://dx.doi.org/10.2172/10120775.

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Ohad, Itzhak, i Himadri Pakrasi. Role of Cytochrome B559 in Photoinhibition. United States Department of Agriculture, grudzień 1995. http://dx.doi.org/10.32747/1995.7613031.bard.

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The aim of this research project was to obtain information on the role of the cytochrome b559 in the function of Photosystem-II (PSII) with special emphasis on the light induced photo inactivation of PSII and turnover of the photochemical reaction center II protein subunit RCII-D1. The major goals of this project were: 1) Isolation and sequencing of the Chlamydomonas chloroplast psbE and psbF genes encoding the cytochrome b559 a and b subunits respectively; 2) Generation of site directed mutants and testing the effect of such mutation on the function of PSII under various light conditions; 3) To obtain further information on the mechanism of the light induced degradation and replacement of the PSII core proteins. This information shall serve as a basis for the understanding of the role of the cytochrome b559 in the process of photoinhibition and recovery of photosynthetic activity as well as during low light induced turnover of the D1 protein. Unlike in other organisms in which the psbE and psbF genes encoding the a and b subunits of cytochrome b559, are part of an operon which also includes the psbL and psbJ genes, in Chlamydomonas these genes are transcribed from different regions of the chloroplast chromosome. The charge distribution of the derived amino-acid sequences of psbE and psbF gene products differs from that of the corresponding genes in other organisms as far as the rule of "positive charge in" is concerned relative to the process of the polypeptide insertion in the thylakoid membrane. However, the sum of the charges of both subunits corresponds to the above rule possibly indicating co-insertion of both subunits in the process of cytochrome b559 assembly. A plasmid designed for the introduction of site-specific mutations into the psbF gene of C. reinhardtii. was constructed. The vector consists of a DNA fragment from the chromosome of C. reinhardtii which spans the region of the psbF gene, upstream of which the spectinomycin-resistance-conferring aadA cassette was inserted. This vector was successfully used to transform wild type C. reinhardtii cells. The spectinomycin resistant strain thus obtained can grow autotrophically and does not show significant changes as compared to the wild-type strain in PSII activity. The following mutations have been introduced in the psbF gene: H23M; H23Y; W19L and W19. The replacement of H23 involved in the heme binding to M and Y was meant to permit heme binding but eventually alter some or all of the electron transport properties of the mutated cytochrome. Tryptophane W19, a strictly conserved residue, is proximal to the heme and may interact with the tetrapyrole ring. Therefore its replacement may effect the heme properties. A change to tyrosine may have a lesser affect on the potential or electron transfer rate while a replacement of W19 by leucine is meant to introduce a more prominent disturbance in these parameters. Two of the mutants, FW19L and FH23M have segregated already and are homoplasmic. The rest are still grown under selection conditions until complete segregation will be obtained. All mutants contain assembled and functional PSII exhibiting an increased sensitivity of PSII to the light. Work is still in progress for the detailed characterization of the mutants PSII properties. A tobacco mutant, S6, obtained by Maliga and coworkers harboring the F26S mutation in the b subunit was made available to us and was characterized. Measurements of PSII charge separation and recombination, polypeptide content and electron flow indicates that this mutation indeed results in light sensitivity. Presently further work is in progress in the detailed characterization of the properties of all the above mutants. Information was obtained demonstrating that photoinactivation of PSII in vivo initiates a series of progressive changes in the properties of RCII which result in an irreversible modification of the RCII-D1 protein leading to its degradation and replacement. The cleavage process of the modified RCII-D1 protein is regulated by the occupancy of the QB site of RCII by plastoquinone. Newly synthesized D1 protein is not accumulated in a stable form unless integrated in reassembled RCII. Thus the degradation of the irreversibly modified RCII-D1 protein is essential for the recovery process. The light induced degradation of the RCII-D1 protein is rapid in mutants lacking the pD1 processing protease such as in the LF-1 mutant of the unicellular alga Scenedesmus obliquus. In this case the Mn binding site of PSII is abolished, the water oxidation process is inhibited and harmful cation radicals are formed following light induced electron flow in PSII. In such mutants photo-inactivation of PSII is rapid, it is not protected by ligands binding at the QB site and the degradation of the inactivated RCII-D1 occurs rapidly also in the dark. Furthermore the degraded D1 protein can be replaced in the dark in absence of light driven redox controlled reactions. The replacement of the RCII-D1 protein involves the de novo synthesis of the precursor protein, pD1, and its processing at the C-terminus end by an unknown processing protease. In the frame of this work, a gene previously isolated and sequenced by Dr. Pakrasi's group has been identified as encoding the RCII-pD1 C-terminus processing protease in the cyanobacterium Synechocystis sp. PCC 6803. The deduced sequence of the ctpA protein shows significant similarity to the bovine, human and insect interphotoreceptor retinoid-binding proteins. Results obtained using C. reinhardtii cells exposes to low light or series of single turnover light flashes have been also obtained indicating that the process of RCII-D1 protein turnover under non-photoinactivating conditions (low light) may be related to charge recombination in RCII due to back electron flow from the semiquinone QB- to the oxidised S2,3 states of the Mn cluster involved in the water oxidation process.

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Harold, M. P. Kinetics and dynamics of oxidation reactions involving an adsorbed CO species on bulk and supported platinum and copper-oxide. First year annual report, January 1, 1991--December 31, 1991. Office of Scientific and Technical Information (OSTI), lipiec 1991. http://dx.doi.org/10.2172/10109528.

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