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Auswahl der wissenschaftlichen Literatur zum Thema „Reaction of catalytic CO oxidation“
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Zeitschriftenartikel zum Thema "Reaction of catalytic CO oxidation"
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Zhou, Xue-Fei, und 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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Bzovska und 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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Al Soubaihi, Rola Mohammad, Khaled Mohammad Saoud, Myo Tay Zar Myint, Mats A. Göthelid und Joydeep Dutta. „CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst“. Catalysts 11, Nr. 1 (16.01.2021): 131. http://dx.doi.org/10.3390/catal11010131.
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Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.
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Oleksenko, Lyudmila, George Fedorenko, Igor Matushko, Nelly Maksymovych und 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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Dobrosz-Gómez, Izabela, Miguel-Ángel Gómez-García und Jacek Michał Rynkowski. „The Origin of Au/Ce1-xZrxO2 Catalyst’s Active Sites in Low-Temperature CO Oxidation“. Catalysts 10, Nr. 11 (13.11.2020): 1312. http://dx.doi.org/10.3390/catal10111312.
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Gold catalysts have found applications in many reactions of both industrial and environmental importance. Great interest has been paid to the development of new processes that reduce energy consumption and minimize pollution. Among these reactions, the catalytic oxidation of carbon monoxide (CO) is an important one, considering that a high concentration of CO in the atmosphere creates serious health and environmental problems. This paper examines the most important achievements and conclusions arising from the own authorship contributions concerning (2 wt. % Au)/Ce1−xZrxO2 catalyst’s active sites in low-temperature CO oxidation. The main findings of the present review are: (1) The effect of preparing conditions on Au crystallite size, highlighting some of the fundamental underpinnings of gold catalysis: the Au surface composition and the poisoning effect of residual chloride on the catalytic activity of (2 wt. % Au)/Ce1−xZrxO2 catalysts in CO oxidation; (2) The identification of ion clusters related to gold and their effect on catalyst’ surface composition; (3) The importance of physicochemical properties of oxide support (e.g., its particle size, oxygen mobility at low temperature and redox properties) in the creation of catalytic performance of Au catalysts; (4) The importance of oxygen vacancies, on the support surface, as the centers for oxygen molecule activation in CO reaction; (5) The role of moisture (200–1000 ppm) in the generation of enhanced CO conversion; (6) The Au-assisted Mars-van Krevelen (MvK) adsorption–reaction model was pertinent to describe CO oxidation mechanism. The principal role of Au in CO oxidation over (2 wt. % Au)/Ce1−xZrxO2 catalysts was related to the promotion in the transformation process of reversibly adsorbed or inactive surface oxygen into irreversibly adsorbed active species; (7) Combination of metallic gold (Au0) and Au-OH species was proposed as active sites for CO adsorption. These findings can help in the optimization of Au-containing catalysts.
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Eid, Kamel, Yahia Ahmad, Assem Mohamed, Anas Elsafy und 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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Mahmood, Asif, Shahid M. Ramay, Yousef Al-Zeghayer, Sajjad Haider, Muhammad Ali Shar und Yasir Khalid. „Thermal Treatment Effect on Catalytic Activity of Au/TiO2 for CO Oxidation“. Applied Mechanics and Materials 548-549 (April 2014): 254–58. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.254.
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A novel and well-organized study for the synthesis and enhanced catalytic activity of Au/TiO2catalysts has been developed. A momentous improvement in the catalytic activity of Au/TiO2in CO oxidation and preferential oxidation reaction by thermal treatment has been studied. Au/TiO2catalyst (Au (1 wt.%) supported on TiO2) was prepared by conventional deposition-precipitation method with NaOH followed by washing, drying and calcination in air at 400 °C for 4 h. Thermal treatment of Au/TiO2was performed at 450 °C under 0.05 mTorr. The activity of the catalysts has been examined in the reaction of CO oxidation and preferential oxidation (PROX) at 25-250 °C. The catalytic performance was found to be strongly affected by thermal treatment of the prepared catalyst prior to the reaction. Heat treatment after Au deposition has a positive effect on the CO oxidation performance. This is attributed to the introduction of a stronger interaction between the oxide and Au which improves the catalytic activity.
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Kappis, Konstantinos, Christos Papadopoulos, Joan Papavasiliou, John Vakros, Yiannis Georgiou, Yiannis Deligiannakis und George Avgouropoulos. „Tuning the Catalytic Properties of Copper-Promoted Nanoceria via a Hydrothermal Method“. Catalysts 9, Nr. 2 (01.02.2019): 138. http://dx.doi.org/10.3390/catal9020138.
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Copper-cerium mixed oxide catalysts have gained ground over the years in the field of heterogeneous catalysis and especially in CO oxidation reaction due to their remarkable performance. In this study, a series of highly active, atomically dispersed copper-ceria nanocatalysts were synthesized via appropriate tuning of a novel hydrothermal method. Various physicochemical techniques including electron paramagnetic resonance (EPR) spectroscopy, X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy (SEM), Raman spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed in the characterization of the synthesized materials, while all the catalysts were evaluated in the CO oxidation reaction. Moreover, discussion of the employed mechanism during hydrothermal route was provided. The observed catalytic activity in CO oxidation reaction was strongly dependent on the nanostructured morphology, oxygen vacancy concentration, and nature of atomically dispersed Cu2+ clusters.
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LÓPEZ-CARREÑO, L. D. „EFFECTS OF FINITE REACTION RATES ON THE KINETIC PHASE TRANSITIONS IN THE CATALYTIC OXIDATION OF CARBON MONOXIDE“. Surface Review and Letters 09, Nr. 05n06 (Oktober 2002): 1735–39. http://dx.doi.org/10.1142/s0218625x02004311.
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Oxidation of carbon monoxide is one of the most extensively studied heterogeneous catalysis reactions, being important among other applications in automobile-emission control. Catalytic oxidation of carbon monoxide on platinum (111) surface was simulated by the Monte Carlo technique following an extended version of the model proposed by Ziff, Gulari and Barshad (ZGB). In the simulation, a simple square two-dimensional lattice of active sites replaces the surface of the catalyst. Finite reaction rates for (i) diffusion of the reactive species on the surface, (ii) reaction of a CO molecule with an oxygen atom in a nearest neighbor site, and (iii) desorption of unreacted CO molecules, have been taken into account. The produced CO 2 desorbs instantly. The average coverage of O, CO and the CO 2 production rate for a steady state configuration, as a function of the normalized CO partial pressure (P CO ), shows two kinetic phase transitions. In the ZGB model these transitions occur at P CO ≈ 0.39 and P CO ≈ 0.53. For 0.39 < P CO < 0.53 a reactive ( CO 2 production) steady state is found. Outside of the interval, the only steady state is a poisoned catalyst of pure CO or pure O. Our results show that finite reaction rates shift the values in which these phase transitions occur.
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Han, Qiuwan, Dongyang Zhang, Jiuli Guo, Baolin Zhu, Weiping Huang und Shoumin Zhang. „Improved Catalytic Performance of Au/α-Fe2O3-Like-Worm Catalyst for Low Temperature CO Oxidation“. Nanomaterials 9, Nr. 8 (03.08.2019): 1118. http://dx.doi.org/10.3390/nano9081118.
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The gold catalysts supported on various morphologies of α-Fe2O3 in carbon monoxide (CO) oxidation reaction have been studied for many researchers. However, how to improve the catalytic activity and thermal stability for CO oxidation is still important. In this work, an unusual morphology of α-Fe2O3 was prepared by hydrothermal method and gold nanoparticles were supported using a deposition-precipitation method. Au/α-Fe2O3 catalyst exhibited great activity for CO oxidation. The crystal structure and microstructure images of α-Fe2O3 were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and the size of gold nanoparticles was determined by transmission electron microscopy (TEM). X-ray photoelectron spectra (XPS) and Fourier transform infrared spectra (FTIR) results confirmed that the state of gold was metallic. The 1.86% Au/α-Fe2O3 catalyst calcined at 300 °C had the best catalytic performance for CO oxidation reaction and the mechanism for CO oxidation reaction was also discussed. It is highly likely that the small size of gold nanoparticle, oxygen vacancies and active sites played the decisive roles in CO oxidation reaction.
Dissertationen zum Thema "Reaction of catalytic CO oxidation"
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Doory, Layla Kim. „Development of catalytic reactor designs for enhanced CO oxidation“. Thesis, University College London (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282799.
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Wang, Tongyu [Verfasser], Karsten [Akademischer Betreuer] Reuter und 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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Neugebohren, Jannis. „Implementing Ion Imaging to Probe Chemical Kinetics and Dynamics at Surfaces“. Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E43B-1.
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Janák, Marcel. „Diagnostika polovodičů a monitorování chemických reakcí metodou SIMS“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443241.
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Hmotnostná spektrometria sekundárnych iónov s analýzou doby letu (TOF-SIMS) patrí vďaka vysokej citlivosti na prvkové zloženie medzi významné metódy analýzy pevných povrchov. Táto práca demonštruje možnosti TOF-SIMS v troch odlišných oblastiach výskumu. Prvá časť práce sa zaoberá lokalizáciou defektov vysokonapäťových polovodičových súčiastok, ktorá je nevyhnutná k ich ďalšiemu skúmaniu metódou TOF-SIMS. Bola navrhnutá experimentálna zostava s riadiacim softvérom umožňujúca automatizované meranie záverného prúdu v rôznych miestach polovodičový súčiastok. Druhá časť práce sa zaoberá kvantifikáciou koncentrácie Mg dopantov v rôznych hĺbkach vzoriek AlGaN. Kvantifikácia je založená na metóde RSF a umožňuje charakterizáciu AlGaN heteroštruktúr určených na výrobu tranzistorov s vysokou elektrónovou mobilitou (HEMT) alebo na výrobu rôznych optoelektronických zariadení. Sada 12 AlGaN kalibračných vzoriek dopovaných Mg, určených na kvantifikáciu hĺbkových profilov, bola pripravená metódou iónovej implantácie. Posledná časť práce demonštruje možnosti metódy TOF-SIMS vo výskume heterogénnej katalýzy. Hlavným objektom nášho výskumu je dynamika oxidácie CO na oxid uhličitý na polykryštalickom povrchu platiny za tlakov vysokého vákua. V tejto práci prezentujem prvé TOF-SIMS pozorovanie časopriestorových vzorov v reálnom čase, ktoré vznikajú v dôsledku rôzneho pokrytia povrchu Pt reaktantmi. Výsledky TOF-SIMS experimentu boli porovnané s výsledkami podobného experiment v rastrovacom elektrónovom mikroskope (SEM).
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Wolff, Niklas von. „Reaction mechanisms of CO₂ activation and catalytic reduction“. Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS580.
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L’utilisation du dioxyde de carbone (CO₂) comme source de composés C1 pour la chimie fine est intéressante d’un point de vue économique et pour des raisons écologiques. Issu de l’oxydation de la matière carbonée, le CO₂ est un gaz non-toxique, abondant et peu coûteux. Sa transformation en produits chimiques présentant de hautes valeurs ajoutées est actuellement entravée par sa stabilité thermodynamique. Afin de développer de nouveaux processus et catalyseurs pour la réduction catalytique du CO₂, une compréhension détaillée des mécanismes réactionnels de l’activation et de la réduction de ce gaz est nécessaire. En utilisant comme catalyseurs des paires de Lewis frustrée (FLPs) contenant une base azotée liée à un ion silicénium, les influences respectives de l’adduit CO₂-FLP et du réducteur ont été déterminées expérimentalement et par calcul DFT dans le cadre de l’hydroboration du CO₂ en équivalent de méthanol. Une nouvelle réaction visant à la création de liaisons carbone–carbone par le transfert du fragment pyridyle de molécules de pyridylsilanes (C₅H₄N–SiMe₃) sur le CO₂ était également étudiée. Le mécanisme réactionnel de cette transformation a été établi sur la base de calculs théoriques. Nous avons montré le double rôle du CO₂ qui est à la fois un réactif et un catalyseur de la réaction de transfert du groupe pyridyle. La compréhension fine de cette réaction nous a permis de l’étendre à la formation de sulfones et sulfonamides qui sont des groupements chimiques essentiels dans le domaine pharmaceutique. En utilisant le SO₂ à la fois comme catalyseur et réactif, des silanes aromatiques et hétéro-aromatiques ont été transformés en sulfones correspondants en une seule étape. Finalement, nous avons trouvé un couplage croisé original, de type Hiyama, entre espèces aromatiques électrophiles et des espèces C(sp2)–Si nucléophiles en présence de SO₂The use of CO₂ as a C1 chemical feedstock for the fine chemical industry is interesting both economically and ecologically, as CO₂ is non-toxic, abundant and cheap. Nevertheless, transformations of CO₂ into value-added products is hampered by its high thermodynamic stability and its inertness toward reduction. In order to design new catalysts able to overcome this kinetic challenge, a profound understanding of the reaction mechanisms at play in CO₂ reduction is needed. Using novel N/Si+ frustrated Lewis pairs (FLPs), the influence of CO₂ adducts and different hydroborane reducing agents on the reaction mechanism in the catalytic hydroboration of CO₂ were investigated, both by DFT calculations and experiments. In a second step, the reaction mechanism of a novel reaction for the creation of C–C bonds from CO₂ and pyridylsilanes (C₅H₄N–SiMe₃) was analyzed by DFT calculations. It was shown that CO₂ plays a double role in this transformation, acting both as a catalyst and a C1-building block. The fine understanding of this transformation then led to the development of a novel approach for the synthesis of sulfones and sulfonamides. Starting from SO₂ and aromatic silanes/amine silanes, these products were obtained in a single step under metal-free conditions. Noteworthy, sulfones and sulfonamides are common motifs in organic chemistry and found in a variety of highly important drugs. Finally, this concept was extended to aromatic halides as coupling partners, and it was thus shown for the first time that a sulfonylative Hiyama reaction is a possible approach to the synthesis of sulfones
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Anantharaman, Bharthwaj. „Reaction mechanisms for catalytic partial oxidation systems : application to ethylene epoxidation“. Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32328.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2005.Includes bibliographical references.
With the rapid advances in kinetic modeling, building elementary surface mechanisms have become vital to understand the complex chemistry for catalytic partial oxidation systems. Given that there is selected experimental knowledge on surface species and a large number of unknown thermochemical, rate parameters, the challenge is to integrate the knowledge to identify all the important species and accurately estimate the parameters to build a detailed surface mechanism. This thesis presents computational methodology for quickly calculating thermodynamically consistent temperature/coverage-dependent heats of formation, heat capacities and entropies, correction approach for improving accuracy in heats of formation predicted by composite G3- based quantum chemistry methods, and detailed surface mechanism for explaining selectivity in ethylene epoxidation. Basis of the computational methodology is the Unity Bond Index- Quadratic Exponential Potential (UBI-QEP) approach, which applies quadratic exponential potential to model interaction energies between atoms and additive pairwise energies to compute total energy of an adsorbed molecule. By minimizing the total energy subject to bond order constraint, formulas for chemisorption enthalpies have been derived for surface species bound to on-top, hollow and bridge coordination sites with symmetric, asymmetric and chelating coordination structures on transition metal catalysts. The UBI-QEP theory for diatomics has been extended for polyatomic adsorbates with empirical modifications to the theory.
(cont.) Formulas for activation energies have been derived for generic reaction types, including simple adsorption, dissociation-recombination, and disproportionation reactions. Basis of the correction approach is the Bond Additivity Correction (BAC) procedures, which apply atomic, molecular and bond- wise modifications to enthalpies of molecules predicted by G3B3 and G3MP2B3 composite quantum chemistry methods available in Gaussian® suite of programs. The new procedures have improved the accuracy of thermochemical properties for open and closed shell molecules containing various chemical moieties, multireference configurations, isomers and degrees of saturation involving elements from first 3 rows of the periodic table. The detailed mechanism explains the selectivity to ethylene oxide based on the parallel branching reactions of surface oxametallacycle to epoxide and acetaldehyde. Using Decomposition Tree Approach, surface reactions and species have been generated to develop a comprehensive mechanism for epoxidation. As a result of these developments in the thesis, chemisorption enthalpies can now be estimated within 3 kcal/mol of experimental values for transition metal catalysts and enthalpies predicted by G3B3 and G3MP2B3 Gaussian methods can be corrected within 0.5 kcal/mol. Examples of heterogeneous reaction systems involving silver-catalyzed ethylene epoxidation demonstrate the effectiveness of the methodologies developed in this work.
by Bharthwaj Anantharaman.
Ph.D.
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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 COAu-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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Nuhu, Abdullahi. „Catalytic reaction of CO and alcohols over supported gold catalysts“. Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54729/.
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Studies of CO, methanol and some higher alcohol oxidations over gold supported on TiO2 (Degussa), Y-AI2O3 and SiCh were investigated. The methods of preparation of catalysts used are deposition precipitation and incipient wetness impregnation. Several parameters have been investigated for CO oxidation over Au/TiO2 prepared by deposition precipitation, such as temperature programmed pulse flow reaction, isothermal and continuous flow CO oxidation, anaerobic CO reaction, calcination temperature, effect of moisture (in the presence of water, and methanol), kinetics and CO oxidation in the presence of hydrogen etc. The catalysts are demonstrated to have high activity even at room temperature. Gold supported on TiO 2 (Degussa) was characterized by BET surface area method, powder X-ray diffraction, SEM, EDAX, XPS, and Raman spectroscopy. The CO oxidation reaction studied on A11/Y-AI2O3 and Au/SiC catalysts prepared by deposition precipitation (DP) and incipient wetness impregnation (IW) methods showed that the A11/Y-AI2O3 catalyst prepared by DP method is much more active than A11/Y-AI2O3 and Au/SiC 2 prepared by the incipient wetness impregnation method. Presumably, the low performances of the IW catalysts are ascribed due to presence of chloride which leads to gold sintering in the catalyst. However, the performance of these catalysts with respect to CO oxidation was less than the Au/TiO 2 catalyst prepared by DP method. The characterization of the catalyst shows the BET surface area of A11/Y-AI2O3 and Au/SiCh catalysts to be 128 and 320m
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Wang, Jiamin. „Exploring Strategies to Break Adsorption-Energy Scaling Relations in Catalytic CO Oxidation“. Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96537.
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An atomistic control of chemical bonds formation and cleavage holds the key to making molecular transformations more energy efficient and product selective. However, inherent scaling relations among binding strengths of adsorbates on various catalytic materials often give rise to volcano-shaped relationships between the catalytic activity and the affinity of critical intermediates to the surface. The optimal catalysts should bind the reactants 'just right', i.e., neither too strong nor too weak, which is the Sabatier's principle. It is extremely useful for searching promising catalysts, but also imposes serious constraints on design flexibility. Therefore, how to circumvent scaling constraints is crucial for advancing catalytic science. It has been shown that hot electrons can selectively activate the chemical bonds that are not responsive to phonon excitation, thus providing a rational approach beyond scaling limitation. Another emerging yet effective way to break the scaling constraint is single atom catalysis. Strong interactions of supported single atoms with supports dramatically affect the electronic structure of active sites, which reroutes mechanistic pathways of surface reactions. In my PhD research, we use CO oxidation reaction on metal-based active sites as a benchmark system to tailor mechanistic pathways through those two strategies 1) ultra-fast laser induced nonadiabatic surface chemistry and 2) oxide-supported single metal catalysis, with the aim to go beyond the Sabatier activity volcano in metal catalysis.Doctor of Philosophy
Catalysis is the process of increasing the chemical reaction rate by lowering down the activation barrier. There are three different types of catalysis including enzyme, homogeneous, and heterogeneous catalysis. Heterogeneous catalytic reactions involve a sequence of elementary steps, e.g., adsorption of reactants onto the solid surface, transformation of adsorbed species, and desorption of the products. However, the existing scaling relations among binding energies of reaction intermediates on various catalytic materials lead to volcano-shaped relationships, which show the reaction activity versus the binding energy of critical intermediates. The optimal catalysts should bind the reaction intermediates neither too strong nor too weak. This is the Sabatier's principle, which provides useful guidance for searching promising catalysts. But it also imposes the constraint on the attainable catalytic performance. How to break the constraint to further improve the catalytic activity is an emerging problem. The recent studies have shown that the hot surface electrons on the metal surfaces induced by the ultra-fast laser can selectively activate the chemical bonds, thus providing a rational approach beyond scaling constraints. Another way to break the scaling constraint is single atom catalysis. The metal oxides are frequently used as the support to stabilize the single metal atoms. The strong interaction between the single metal atoms and the support affects the electronic structure of the catalysts. Thereby catalytic reactions on the single metal atoms catalyst are very different from that on metal surfaces. In my PhD research, we use CO oxidation reaction as a benchmark system, to tailor reaction pathways through those two strategies on 1) Ru(0001) under ultra-fast laser pulse and 2) Ir single metal atoms supported on spinel oxides, to go beyond Sabatier activity volcano in metal catalysis.
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Lau, Ngai Ting. „Catalytic reduction of sulfur dioxide and nitric oxide /“. View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CENG%202006%20LAU.
Der volle Inhalt der QuelleBücher zum Thema "Reaction of catalytic CO oxidation"
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1851-1941, Miller Isaiah M., und Langley Research Center, Hrsg. Optimization of the catalytic oxidation of CO for closed-cycle CO laser applications. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1985.
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Modeling of carbon monoxide oxidation kinetics over NASA carbon dioxide laser catalysts: Final project report. [Washington, DC: National Aeronautics and Space Administration, 1989.
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Chabal, Y. J., S. B. Christman, V. A. Burrows, N. A. Collins und S. Sundaresan. „Self-sustained Kinetic Oscillations in the Catalytic CO Oxidation on Platinum“. In 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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Levec, Janez. „Opportunities in Catalytic Reaction Engineering. Examples of Heterogeneous Catalysis in Water Remediation and Preferential CO Oxidation“. In Chemical Engineering, 103–24. Chichester, UK: John Wiley & Sons, Ltd, 2005. http://dx.doi.org/10.1002/0470025018.ch5.
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Coulstont, George W., und Gary L. Haller. „Is There a Distribution of Transition State Energies in the Reaction Coordinate of CO Oxidation on Pt Foil?“ In 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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Destro, Priscila. „AuCu Nanoparticles Applied on Heterogeneous Catalysis: Studies About the Stability of Nanoparticles Under Redox Pre-treatments and Application in CO Oxidation Reaction“. In 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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Jaenicke, S., G. K. Chuah und J. Y. Lee. „Catalytic CO Oxidation Over Manganese-Containing Perovskites“. In Fourth Symposium on our Environment, 131–38. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-2664-9_13.
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Plath, Peter J., und Carsten Ballandis. „Catalytic Oxidation of CO—A Striking Example of Synergetics“. In Complexity and Synergetics, 87–100. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-64334-2_8.
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Bunten, K. A., D. H. Farrar, A. Lough und A. J. Poë. „Catalytic Oxidation of Binap on (Binap)Rh(Co)ci“. In Principles and Methods for Accelerated Catalyst Design and Testing, 375–81. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0554-8_24.
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Watanabe, Yoshihito, Kazuya Yamaguchi und Isao Morishima. „Preparation, Characterization, and Reaction of an Oxo-Fe(V)-Porphyrin Complex“. In The Activation of Dioxygen and Homogeneous Catalytic Oxidation, 486. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-3000-8_77.
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Partenheimer, Walt. „Thermodynamic and Kinetic Studies to Elucidate the Amoco Co/Mn/Br Autoxidation (‘MC’) Catalyst“. In The Activation of Dioxygen and Homogeneous Catalytic Oxidation, 474. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-3000-8_65.
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Böcker, D., und E. Wicke. „In-Situ IR Study During Oscillations of the Catalytic CO Oxidation“. In Temporal Order, 75–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-70332-4_10.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Reaction of catalytic CO oxidation"
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Manrique Carrera, Arturo, Jeevan Jayasuriya und Torsten Fransson. „Catalytic Partial Oxidation of Natural Gas in Gas Turbine Applications“. In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95338.
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The demands of emissions, combustion efficiency over a wider operational range, and fuel flexibility for industrial gas turbine applications are expected to increase in the coming years. Currently, it is common the use of a stabilizing piloting diffusion flame during part load operation, this flame is accountable for an important part of the thermal NOx emissions on partial load, and in some cases also at full load operation. On the other hand Catalytic Partial Oxidation (CPO) of natural gas is a technique used in petrochemical industry for the Fischer-Tropsch process and for H2 production, and is based in the production of Syn-Gas rich in H2 and CO. The present work explores the possibility to use the CPO of natural gas in industrial gas turbine applications, it is based in experiments performed between 5 and 13 bar using an arrangement of Rh based catalyst and CH4. The experiments were done at the Catalytic Combustion High Pressure Test Facility, at the Royal Institute of Technology (KTH) in Sweden. The gas produced leaves the CPO reactor between 700 and 850 °C and it is rich in H2 and CO. It was found that the most important parameter after reaching the light off temperature in the CPO reactor is the equivalence ratio Φ, which evidences the kinetically controlled regime in the Rh catalyst that depends on O2 availability. The H2/CO ratio is close to the theoretical value of 2 and the selectivity towards H2 and CO are 90% and 95% respectively while the CH4 conversion reached approximately 55%. Pressure on the other hand had a small negative influence in the tested pressure range and it is more relevant at richer fuel conditions (high equivalence ratios). The CPO process had shown that it is relatively easy to control the operation temperature of the catalyst. This temperature is kept below the maximum allowed by reducing the O2 availability. The high temperature Syn-Gas gas produced through CPO process could be burnt in the downstream of the catalysts steadily at flame temperatures below the thermal-NOx threshold. The CPO reactor could provide the flame stabilization function at a wide range of operational conditions, and replace the diffusion piloting flame. This approach could cope with NOx and CO emissions in a wider operational range and offers the possibility of using different fuels as the reaction controlling factor is O2 availability. Furthermore, an initial design of a possible combustion strategy downstream of the CPO reactor is also presented.
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Wierzbicki, Teresa A., Ivan C. Lee und Ashwani K. Gupta. „Catalytic Oxidation of Jet Fuel Surrogates in a Meso-Scale Combustor“. In ASME 2015 Power Conference collocated with the ASME 2015 9th International Conference on Energy Sustainability, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/power2015-49208.
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Oxidation behavior of dodecane and two mixtures of dodecane and m-xylene (90/10 wt. % and 80/20 wt. %) over an Rh catalyst in a meso-scale heat recirculating combustor was examined to isolate the effect of aromatic content on performance. The fuel conversion, product speciation and reaction kinetics were calculated, and the global combustion behavior observed. The results showed that increasing the amount of m-xylene in the fuel increased the fuel conversion from 85% (pure dodecane) to 92% (90/10) and further to 98% (80/20). The presence of xylene also significantly increased CO2/H2O selectivity and de-creased CO/H2 selectivity. Global activation energy increased linearly with increase in xylene content, supporting that addition of aromatic species to fuel lowers the overall reactivity. The non-catalytic reaction was also simulated using Chemkin software to determine the effect of the Rh catalyst on the combustor performance. The results revealed that the catalyst promotes total oxidation over partial oxidation, and lowers the global activation energy by up to 70%.
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Prince, Juan C., Ce´sar Trevin˜o und Mario Diaz. „Numerical Modeling of an Automotive Catalyst for CO and NO Emissions“. In ASME 2008 2nd International Conference on Energy Sustainability collocated with the Heat Transfer, Fluids Engineering, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/es2008-54218.
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Catalytic combustion is useful to avoid emission of carbon monoxide and nitrogen oxides into the environment. The widespread use of the catalytic converter was the response of the automotive industry to the legislation of the countries which sets limits on pollutant emissions. The catalytic combustion of CO + NO and air mixtures in a planar stagnation-point flow over a platinum foil is studied numerically in this paper. In order to optimize the operation of the platinum converter, chemical kinetic knowledge is necessary, therefore a kinetic model is proposed, based on elementary reaction steps, that allows to describe the experiments quantitatively. The heterogeneous reaction mechanism is modeled with the dissociative adsorption of the molecular oxygen and the nondissociative adsorption of CO, together with a surface reaction of the Langmiur-Hinshelwood type and the desorption reaction of the adsorbed products, CO(s) and NO(s). The resulting governing equations based on the boundary layer theory have been numerically integrated by using Runge-Kutta method and the response curve has been obtained as a function of the initial mixture concentration. The reduction of NO and oxidation of CO in absence and presence of O2 has been investigated, and the optimal oxygen feeding into the initial mixture concentration for the maximum reduction of CO and NO was found and corresponds to the reported experimental results.
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Raoufi, Arman, Sagar Kapadia und James C. Newman. „Sensitivity Analysis and Computational Optimization of Fuel Reformer“. In ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2016 Power Conference and the ASME 2016 10th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fuelcell2016-59110.
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In this study, the catalytic combustion of methane is numerically investigated using an unstructured, implicit, fully coupled finite volume approach. Nonlinear system of equations is solved by Newton’s method. The catalytic partial oxidation of methane over both platinum and rhodium catalysts are studied three-dimensionally. Eight gas-phase species (CH4, CO2, H2O, N2, O2, CO, OH and H2) are considered for the simulation. Surface chemistry is modeled by detailed reaction mechanisms including 24 heterogeneous reactions with 11 surface-adsorbed species for Pt catalyst and 38 heterogeneous reactions with 20 surface-adsorbed species for Rh catalyst. The numerical results are compared with the experimental data and good agreement is observed. The performance of the fuel reformer is analyzed for two different catalysts. The sensitivity analysis for the reactor is performed using three different approaches: finite difference, direct differentiation and adjoint method. The design cycle is performed using two gradient-based optimization algorithms to improve the value of the implemented cost function and optimize the reactor performance.
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Santis-Alvarez, Alejandro J., Majid Nabavi und Dimos Poulikakos. „Self-Sustained Partial Oxidation of N-Butane Triggered by a Hybrid Start-Up Process for Micro-SOFC Devices“. In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62043.
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Micro-solid oxide fuel cell (SOFC) power plants are emerging as a promising alternative for power generation for portable applications due to their low emission of pollutants, high power density and fuel flexibility. Some of the challenges for developing such micro-SOFC power plants are geometrical compactness, fast start-up and self-sustainability at operating conditions. In this work, we present a hybrid start-up process for a micro-SOFC power plant using catalytic oxidation of n-butane over Rh-doped Ce0.5Zr0.5O2 nanoparticles in a small-scale reactor to provide the necessary intermediate operating temperature (500–550 °C) and syngas (CO + H2) as fuel for a micro-SOFC membrane. A short heating wire is used to generate the heat required to trigger the oxidative reaction. The hybrid start-up is investigated for partial oxidation (POX) and total oxidation (TOX) ratios at one specified flow rate. Additionally, the variation of electrical heating time and its influence on the hybrid start-up is evaluated.
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Zuo, Jun, Meiping Wang, Graham T. Reader und Ming Zheng. „Preliminary Thermal Analyses on Diesel Converter Overheating“. In ASME 2004 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/icef2004-0890.
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The use of oxidation catalytic converters (OCC) in Diesel engines has proved to be an effective method to reduce emissions of total hydrocarbons (THC), carbon monoxide (CO), and the soluble organic fractions (SOF) of particulate matter (PM). However, the exothermal reaction effected by the oxidation of THC, CO, and especially the soot accumulated in the converters impose a risk of catalytic flow bed overheating that subsequently results in catalyst failure and may cause safety concerns. This paper presents a one-dimensional transient model that uses an energy balance method to analyze the overheating scenario when considering combustible gas reaction, clogged soot burning, and active flow control for a number of Diesel aftertreatment devices. The monolith temperature profiles were simulated by varying the exhaust gas temperature, oxygen concentration, and flow rate. Simulation results indicated that the potential of overheating elevates with increases in combustible gas concentration, soot loading, oxygen concentration, and engine exhaust temperature. The impacts of active control, such as flow reversal control, on converter overheating have also been investigated therein.
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Patel, Sanjay, und K. K. Pant. „Hydrogen Production for PEM Fuel Cells via Oxidative Steam Reforming of Methanol Using Cu-Al Catalysts Modified With Ce and Cr“. In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97209.
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The performance of Cu-Ce-Al-oxide and Cu-Cr-Al-oxide catalysts of varying compositions prepared by co-precipitation method was evaluated for the PEM fuel cell grade hydrogen production via oxidative steam reforming of methanol (OSRM). The limitations of partial oxidation and steam reforming of methanol for the hydrogen production for PEM fuel cell could be overcome using OSRM and can be performed auto-thermally with idealized reaction stoichiomatry. Catalysts surface area and pore volume were determined using N2 adsorption-desorption method. The final elemental compositions were determined using atomic absorption spectroscopy. Crystalline phases of catalyst samples were determined by X-ray diffraction (XRD) technique. Temperature programmed reduction (TPR) demonstrated that the incorporation of Ce improved the copper reducibility significantly compared to Cr promoter. The OSRM was carried out in a fixed bed catalytic reactor. Reaction temperature, contact-time (W/F) and oxygen to methanol (O/M) molar ratio varied from 200–300°C, 3–21 kgcat s mol−1 and 0–0.5 respectively. The steam to methanol (S/M) molar ratio = 1.4 and pressure = 1 atm were kept constant. Catalyst Cu-Ce-Al:30-10-60 exhibited 100% methanol conversion and 152 mmol s−1 kgcat−1 hydrogen production rate at 300°C with carbon monoxide formation as low as 1300 ppm, which reduces the load on preferential oxidation of CO to CO2 (PROX) significantly before feeding the hydrogen rich stream to the PEM fuel cell as a feed. The higher catalytic performance of Ce containing catalysts was attributed to the improved Cu reducibility, higher surface area, and better copper dispersion. Reaction parameters were optimized in order to maximize the hydrogen production and to keep the CO formation as low as possible. The time-on-stream stability test showed that the Cu-Ce-Al-oxide catalysts subjected to a moderate deactivation compared to Cu-Cr-Al-oxide catalysts. The amount of carbon deposited onto the catalysts was determined using TG/DTA thermogravimetric analyzer. C1s spectra were obtained by surface analysis of post reaction catalysts using X-ray photoelectron spectroscopy (XPS) to investigate the nature of coke deposited.
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Depcik, Christopher, Sudarshan Loya und Anand Srinivasan. „Adaptive Carbon Monoxide Kinetics for Exhaust Aftertreatment Modeling“. In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11173.
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Future emission standards are driving the need for advanced control of both Spark (SI) and Compression Ignition (CI) engines. However, even with the implementation of cooled Exhaust Gas Recirculation and Low Temperature Combustion (LTC), it is unlikely that in-cylinder combustion strategies alone will reduce emissions to levels below the proposed standards. As a result, researchers are developing complex catalytic aftertreatment systems to meet these tailpipe regulations for both conventional and alternative combustion regimes. Simulating these exhaust systems requires fast and accurate models suitable for significant changes in inlet conditions. Most aftertreatment devices contain Platinum Group Metals because of their widely documented beneficial catalysis properties; examples include Diesel Oxidation Catalysts, Three-Way Catalysts and Lean NOx Traps. There are kinetic mechanisms available for each of these devices, but often they do not extrapolate well to other formulations. For example, Carbon Monoxide (CO) levels entering a catalyst are significantly different between an SI and CI engine. In addition, modifying engine control to utilize LTC operation can result in an increase in CO levels due to lower combustion efficiency. This adversely affects the conversion capabilities of a catalytic device through increased levels of CO inhibition. Finally, catalyst loading and metal dispersion differences between devices often prohibit a direct extension of kinetic constants. As a result, mechanisms often need recalibration for correct modeling capabilities. In order to begin creating a more predictive kinetic mechanism, this paper simulates CO oxidation as a function of different inlet concentration levels and metal loadings. While aftertreatment devices contain many reactions, modeling of one fundamental reaction is a first step to determine the feasibility of adaptive kinetics. In addition, research into the history of the CO oxidation mechanism over platinum illustrates a more accurate rate expression to utilize in deference to current modeling activities. The authors calibrate this expression to experimental data taking into account significant changes in inlet conditions, metal loading and dispersion values. Model fidelity is determined through the simulation of additional data not part of the initial calibration efforts. In addition, the paper discusses strengths and weaknesses of the model along with how other researchers can help foster adaptive kinetic development.
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Hotz, Nico. „Micro- and Nano-Structured Catalytic Reactor for Biofuel Reforming in a Solar Collector“. In ASME 2012 6th International Conference on Energy Sustainability collocated with the ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/es2012-91338.
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In this study, a novel flow-based method is presented to place catalytic nanoparticles into a reactor by solgelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement. The results of the present study confirm that product gas mixtures with up to 75% hydrogen content and less than 0.2% CO content can be achieved, which is an excellent result. The reactor temperature can be kept as low as 220°C while obtaining a methanol conversion of up to 70%. The used PROX catalyst showed selective CO conversion rates above 99.5% for temperatures between 80 and 100°C in presence of large molar fractions of H2O and CO2.
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Hotz, Nico. „Nano-Structured Catalytic Material for Solar-Powered Biofuel Reforming“. In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89729.
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The main goal of this project is to combine two renewable energy conversion technologies (low-temperature fuel cells and solarthermal collectors) to achieve synergies in terms of cost and energetic efficiency compared to systems based on a single energy source and energy conversion technology. Direct solar-to-electric energy conversion, such as photovoltaics, is currently not economically competitive with traditional electric power generation. Fuel cell technology using alcoholic fuel possibly generated from biomass (e.g. methanol) is not competitive in terms of costs either. The system proposed for this project is based on relatively cheap, commercially available hardware components (intermediate-temperature solar collector, pressurized gas tank, hydrogen-fed Proton Exchange Membrane (PEM) fuel cell) and benefits in terms of energetic efficiency from the cost-free supply of solar heat. By applying micro-fabrication technology and nano-scale structures (e.g. for catalytic surfaces), the efficiency of all individual system components and of the entire system can be increased drastically. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.