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Qiu, Zhiping. "Improvement in hydrogen peroxide bleaching by decreasing manganese-induced peroxide decomposition." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0034/MQ65515.pdf.
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Schmidt, Jeremy T. "Stabilized hydrogen peroxide decomposition dynamics in one-dimensional columns." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Spring2006/j%5Fschmidt%5F050306.pdf.
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Mitchell, Michael S. "Oxidation of biological molecules with bicarbonate-activated hydrogen peroxide and the decomposition of hydrogen peroxide catalyzed by manganese(II) and bicarbonate." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004948.
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Widdis, Stephen. "Computational and Experimental Studies of Catalytic Decomposition of H2O2 Monopropellant in MEMS-based Micropropulsion Systems." ScholarWorks @ UVM, 2012. http://scholarworks.uvm.edu/graddis/239.
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The next generation of miniaturized satellites (“nanosats”) feature dramatically reduced thrust and impulse requirements for purposes of spacecraft attitude control and maneuvering. E↵orts at the University of Vermont have concentrated on developing a MEMS-based chemical micropropulsion system based on a rocket grade hydrogen peroxide (HTP) monopropellant fuel. A key component in the micropropulsion system is the catalytic reactor whose role is to chemically decompose the monopropellant, thereby releasing the fuel’s chemical energy for thrust production. The present study is a joint computational and experimental design e↵ort at developing a MEMS-based micro-reactor for incorporation into a monopropellant micropropulsion system. Numerically, 0D and simplified 2D models have been developed to validate the model and characterize heat and mass di↵usion in the channel. This model will then be extended to a 2D model including all geometric complexities of the catalyst bed geometry with the goal of optimization. Experimentally, both meso and micro scale catalyst geometries have been constructed to prove the feasibility of using RuO2 nanostructures as an in situ in a microchannel.
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Kwan, Wai P. (Wai Pang) 1974. "Kinetics of the Fe(III) initiated decomposition of hydrogen peroxide : experimental and model results." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80211.
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Kwan, Wai P. (Wai Pang) 1974. "Decomposition of hydrogen peroxide and organic compounds in the presence of iron and iron oxides." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29585.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.Includes bibliographical references.
Most advanced oxidation processes use the hydroxyl radical (OH) to treat pollutants found in wastewater and contaminated aquifers because OH reacts with numerous compounds at near diffusion-limited rates. OH can be made by reacting hydrogen peroxide (H202) with either Fe(II) (the Fenton reaction), Fe(1), or iron oxide. This dissertation investigated the factors that influence the decomposition rates of H202 and organic compounds, as well as the generation rate of -OH (VoH), in the presence of dissolved Fe(IH) and iron oxide. The Fe(III)-initiated chain reaction could be the dominant mechanism for the decomposition of H202 and organic compounds. The degradation rates of H14COOH, an OH probe, and H202 were measured in experiments at pH 4 containing either dissolved Fe(III) or ferrihydrite. Combined with the results from experiments using a radical chain terminator, we concluded that a solution chain reaction was important only in the Fe(III) system. In the ferrihydrite system the amount of dissolved Fe was insufficient to effectively propagate the chain reaction. In addition, a nonradical producing H202 loss pathway exists at the oxide surface. The oxidation rate of any dissolved organic compound can be predicted from VOH if the main sinks of -OH in the solution are known. Experiments using H14COOH and ferrihydrite, goethite, or hematite showed that VOH was proportional to the product of the concentrations of surface area and H202. Based on these results, a model was created for predicting the pseudo-first-order oxidation rate coefficients of dissolved organic compounds (korg) in systems containing iron oxide and H202. While our model successfully predicted korg in aquifer sand experiments, it yielded mixed results when compared to measurements from previously published studies.
(cont.) Some factors that could have caused the disagreements between model predictions and measurements were examined to refine our model. Results from experiments containing goethite, H 4COOH, and 2-Chlorophenol showed that H 4COOH detected more OH, which is produced at the oxide surface, than did 2-Chlorophenol. This was attributed to electrostatic attraction between the formate anions and the positively charged oxide surface, and could explain why our model, based on H14COOH, overpredicted the korg values of many neutral compounds.
by Wai P. Kwan.
Ph.D.
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Pakarinen, Darius. "On the mechanism of H2O2 decomposition on UO2-surfaces." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240564.
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Deep geological repository has been investigated as a solution for long term storage of spent nuclear fuel in Sweden for more than 40 years now. The Swedish nuclear fuel and waste management company (SKB) are commissioning the deep repository and they must ensure that nuclear waste is isolated from the environment for thousands of years. During this time the containment must withstand physical stress and corrosion. It is important for a safety analysis to determine the different reactions that could occur during this time. If the physical barriers break down, radiolysis of water will occur. Hydrogen peroxide formed during the radiolysis can oxidize the exposed surface of the fuel, which increases the dissolution of radiotoxic products. Hydrogen peroxide can also catalytically decompose on the surfaces of the fuel. This project set out to figure out the selectivity for catalytic decomposition of hydrogen peroxide. This was to be done analytically with coumarin as a scavenger for detecting hydroxyl radicals formed when hydrogen peroxide decomposes. This produces the fluorescent 7-hydroxycoumarin that with high precision could be measured using spectrofluorometry. The results were giving approximately 0.16% ratio between •OH-production and hydrogen peroxide consumption. Similar experiments were done with ZrO2 for comparison, but the results were largely inconclusive. The effect of bicarbonate (a groundwater constituent) was also investigated. Adding bicarbonate increased the reproducibility of the experiments and increased the dissolution of uranium. Both the uranium and the bicarbonate increased the screening effects which minimized the fluorescent signal output by the 7-hydroxycoumarin.Geologiskt djupförvar av förbrukat kärnbränsle har undersökts som lösning i Sverige i över 40 år nu. Svensk kärnbränslehantering (SKB) driftsätter det geologiska djupförvaret och måste säkerställa att det förbrukade kärnbränslet hålls isolerat från omgivningen i tusentals år. Under denna tid måste förseglingen stå emot fysikalisk stress och korrosion. Det är därför viktigt för en säkerhetsanalys att undersöka de olika reaktioner som kommer ske. Om förseglingen bryts ned kommer kärnbränslet i kontakt med vattnet i berggrunden vilket leder till radiolys av vatten. Väteperoxid som skapas under radiolysen kan sedan oxidera den exponerade ytan av kärnbränslet, detta ökar upplösningen av radiotoxiska produkter. Väteperoxiden kan även katalytisk sönderdelas på kärnbränslets yta. Syftet med arbetet var att få fram selektiviteten för katalytisk sönderdelning av väteperoxid. Detta skulle uppnås analytiskt med kumarin som avskiljare för detektion av hydroxylradikaler som bildas när väteperoxid sönderdelas. Detta producerade det fluorescerande 7-hydroxykumarinet som med hög precision kunde mätas spektrofluorometriskt. Resultaten gav en ca 0,16% förhållande mellan •OH-produktion och väteperoxidkonsumtion. Likartade experiment gjordes med ZrO2 för jämförelse men resultaten var ofullständiga. Effekten av bikarbonat (en beståndsdel i grundvatten) undersöktes också. Genom addition av bikarbonat ökade experimentens reproducerbarhet och ökade även upplösningen av uran. Både uranet och bikarbonaten minskade den utgående fluorescerande signalen från 7-hydroxykumarinet.
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Di, Menno Di Bucchianico Daniele. "The effect of solvent on the thermal and catalysed decomposition of hydrogen peroxide: an experimental and model analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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L'obiettivo di questo lavoro è quello di studiare l'effetto del solvente organico sulla decomposizione del perossido di idrogeno attraverso un'analisi sperimentale e di modellazione cinetica. L’analisi sperimentale esamina la decomposizione termica e la decomposizione catalizzata da γ-allumina in assenza e presenza di acetato di etile come solvente. Determinati attraverso cerimetria, i dati di concentrazione del perossido di idrogeno nei sistemi acquoso-solido e acquoso-organico-solido sono stati esaminati rispetto a parametri di reazione, come temperatura, massa di catalizzatore, rapporto in massa delle fasi acquosa-organica per i sistemi eterogenei-liquidi, e utilizzati nell’analisi di modellazione per definire modelli cinetici previsionali per la reazione di decomposizione nei diversi sistemi. Sulla base dei risultati sperimentali e cinetici, l'effetto del solvente sulla reazione di decomposizione del perossido di idrogeno è stato analizzato.
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Serra, Maia Rui Filipe. "Relation between surface structural and chemical properties of platinum nanoparticles and their catalytic activity in the decomposition of hydrogen peroxide." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85149.
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The disproportionation of H₂O₂ to H₂O and molecular O₂ catalyzed by platinum nanocatalysts is technologically very important in several energy conversion technologies, such as steam propellant thrust applications and hydrogen fuel cells. However, the mechanism of H₂O₂ decomposition on platinum has been unresolved for more than 100 years and the kinetics of this reaction were poorly understood. Our goal was to quantify the effect of reaction conditions and catalyst properties on the decomposition of H₂O₂ by platinum nanocatalysts and determine the mechanism and rate-limiting step of the reaction. To this end, we have characterized two commercial platinum nanocatalysts, known as platinum black and platinum nanopowder, and studied the effect of different reaction conditions on their rates of H₂O₂ decomposition. These samples have different particle size and surface chemisorbed oxygen abundance, which were varied further by pretreating both samples at variable conditions. The rate of H₂O₂ decomposition was studied systematically as a function of H₂O₂ concentration, pH, temperature, particle size and surface chemisorbed oxygen abundance.
The mechanism of H₂O₂ decomposition on platinum proceeds via two cyclic oxidation-reduction steps. Step 1 is the rate limiting step of the reaction. Step 1: Pt + H₂O₂ → H₂O + Pt(O). Step 2: Pt(O) + H₂O₂ → Pt + O₂ + H₂O. Overall: 2 H₂O₂ → O₂ + 2 H₂O. The decomposition of H₂O₂ on platinum follows 1st order kinetics in terms of H₂O₂ concentration. The effect of pH is small, yet statistically significant. The rate constant of step 2 is 13 times higher than that of step 1. Incorporation of chemisorbed oxygen at the nanocatalyst surface resulted in higher initial rate of H₂O₂ decomposition because more sites initiate their cyclic process in the faster step of the reaction. Particle size does not affect the kinetics of the reaction. This new molecular-scale understanding of the decomposition of H₂O₂ by platinum is expected to help advance many energy technologies that depend on the rate of H₂O₂ decomposition on nanocatalysts of platinum and other metals.Ph. D.
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Rustin, Gavin James Mr. "The Analysis of the Decomposition of Hydrogen Peroxide Using a Schiff Base Copper Complex By Cyclic Voltammetry." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/honors/224.
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Copper(II) complexes of Schiff bases can be used in the catalysis of hydrogen peroxide to create water and oxygen. The mechanism and the kinetics of this disproportionation reaction by a dimeric copper(II) complex [CuSALAD]2 are studied in this experiment, where SALAD refers to a Schiff Base ligand formed from salicyaldehyde and 1S,2S-D(+)-1-phenyl-2-amino-1,3-propanediol. By using cyclic voltammetry, the oxidation-reduction processes of a reaction may be monitored. The [CuSALAD]2 is initially reacted with a base such as imidazole to form the catalytic species, and the ratio of the copper(II) complex to the imidazole was found to be 1:4, consistent with previous electron absorption (UV-Vis) spectroscopy experiments. The reduction and oxidation half waves of the copper(II) catalyst are followed via cyclic voltammetry to determine if the copper(II) center undergoes reduction to copper(I) during the hydrogen peroxide catalysis. It appears that while the major oxidation and reduction half wave potentials, E1/2=6.51x10-2V, are unchanged during the decomposition, an additional oxidation wave (E1/2=1.43x10-1V) is observed in the absence of oxygen, suggesting some portion of the copper is reduced. With this information, a mechanism was proposed having copper as a catalyst and creating an intermediate that would form the water and the elemental oxygen.
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Beng, Timothy Kum. "Kinetics and mechanism of the catalysis of the decomposition of hydrogen peroxide by Schiff base complexes of copper(II)." [Johnson City, Tenn. : East Tennessee State University], 2004. http://etd-submit.etsu.edu/etd/theses/available/etd-1113104-182005/unrestricted/BengT120104f.pdf.
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Thesis (M.S.)--East Tennessee State University, 2004.Title from electronic submission form. ETSU ETD database URN: etd-1113104-182005 Includes bibliographical references. Also available via Internet at the UMI web site.
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Eid, Feras. "Design, fabrication, and characterization of a MEMS steam-generating device based on the decomposition of high-test hydrogen peroxide." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61596.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 147-152).
Microscale ejector pumps offer the potential for high flow rate pumping of gases, a functionality that is greatly needed in MEMS technology. These pumps have many additional characteristics, such as their simplicity of design and their lack of moving parts, which favor them over other state-of-the-art MEMS gas pumps. One of the challenges associated with driving ejector pumps, however, is providing a compact source of motive fluid. This fluid is the high-speed gas that drives the pumping action. The current thesis presents a MEMS device capable of generating steam at speeds suitable for driving an ejector pump in a compact fashion. To that end, the device utilizes the homogeneous catalytic decomposition of hydrogen peroxide. Analysis shows that a MEMS ejector pump driven by this device is capable of handling mass flow rates per unit pump volume on the order of 10-2 g/s/cm 3, which are two orders of magnitude higher than those of state-of-the art MEMS gas pumps. In addition to pumping, the steam generator may also be used for microrocket thrust generation in micropropulsion applications. In this thesis, the design, fabrication, testing, and successful demonstration of the MEMS steam generator are presented. The device consists of a mixing section for the peroxide and catalyst streams, a reactor section where the peroxide decomposes, and finally a nozzle section where the gaseous products of the decomposition are accelerated to the required velocities. To design the device, multidomain (chemical, thermal, and fluidic) numerically-implemented modeling is used to study the underlying physics and arrive at an optimized, microfabricatable design. The modeling takes into account the key challenges of thermal management, achieving fast mixing, and boundary layer compensation. The device is then fabricated from a stack of four silicon wafers and one Pyrex wafer using deep reactive ion etching and wafer bonding. The modeling also guides the design of a micabased ceramic package which provides both thermal insulation and piping ports. The system is then experimentally tested using high-test hydrogen peroxide and ferrous chloride tetrahydrate solution as the catalyst. The overall initial peroxide mass fraction is varied between 83% and 71%. The device is characterized using temperature measurements, refractive index analysis, and visual inspection during operation. Successful performance is demonstrated via the full decomposition of the peroxide and the complete vaporization of the water produced. The experimental results are also compared with those from the simulation. Good agreement is observed between experiment and theory, providing comprehensive model verification. The realization and demonstration of this steam generator promise significant enhancements in MEMS technology, particularly in the fields of gas pumping and micropropulsion.
by Feras Eid.
Ph.D.
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Davis, John D. Jr. "Spectroscopic Examination of the Catalytic Decomposition of hydrogen Peroxide by a Copper (II) Complex of a Dissymmetric Schiff Base and an Imidazole Derivative." Digital Commons @ East Tennessee State University, 2003. https://dc.etsu.edu/etd/801.
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Previous studies involving copper (II) complexed with a dissymmetric Schiff base and imidazole derivatives had identified catalase activity of these complexes towards H2O2. Reactions such as this are of great interest due to the important role of copper-based complexes in biological systems. Our research has been conducted to add to the base of knowledge regarding the efforts of other researchers to investigate copper complexes that exhibit similar reactivity as copper-based proteins towards dioxygen. The copper complex chosen for this study contained a tri-dentate Schiff base adduct which, when complexed with an imidazole derivative, limited the manner in which peroxo adducts could bind while providing distinct spectral peaks which were used to conduct kinetic studies. Our results indicate a reaction mechanism by which the role of the complexed copper (II) ion is to activate the peroxo adduct for decomposition through reactions with other peroxide molecules, dioxygen, and water.
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Davis, John D. "Spectroscopic examination of the catalytic decomposition of hydrogen peroxide by a copper (II) complex of a dissymmetric Schiff base and an imidazole derivative." [Johnson City, Tenn. : East Tennessee State University], 2003. http://etd-submit.etsu.edu/etd/theses/available/etd-0715103-171753/unrestricted/DavisJ072503F.pdf.
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Thesis (M.S.)--East Tennessee State University, 2003.Title from electronic t.p. ETSU ETD database URN: etd-0715103-171753. Includes bibliographical references. Also available via Internet at the UMI web site.
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Gagliardi, Anna. "A new, environmentally friendly approach towards the synthesis of epoxy functionalized poly-DCPD." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19196/.
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Epoxy resins are thermosetting resins with excellent mechanical properties, high adhesiveness to many substrates, good thermal stability and chemical resistances, high tensile strength and modulus, and ease of handling and processability. Currently epoxy resins are very popular as fiber-reinforced materials, general-purpose adhesives, high-performance coatings, paints and encapsulating materials. During the last decades, demand for material systems with precise control over multiple properties has increased, as well as the necessity to find new sustainable processes for their manufactory. Thanks to a collaboration between the German company Rutgers and professor Raveendran of the University of Amsterdam, the work presented here was focused on a novel, environmentally friendly path for the achievement of epoxy functionalized poly-DCPD. Reaction of epoxidation of DCPD with hydrogen peroxide, catalyzed by various metal oxides, was studied and optimized in view of a future polymerization of the functionalized monomers. Direct epoxidation of poly-DCPD was also attempted.
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Pereira, Luís Gustavo Ferroni. "Desenvolvimento de materiais catalíticos à base de óxidos mistos para a decomposição do monopropelente peróxido de hidrogênio." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-24072014-152509/.
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Este trabalho teve como objetivo o desenvolvimento de materiais catalíticos à base de óxidos mistos, de baixo custo, para serem empregados como catalisadores mássicos, na decomposição do peróxido de hidrogênio 90%, em massa, possibilitando múltiplas partidas a frio em um micropropulsor de satélites a monopropelente. Foram utilizados diferentes métodos de síntese de óxidos mistos com altos teores de manganês e cobalto. Os materiais foram avaliados, preliminarmente, na decomposição espontânea do peróxido de hidrogênio em bancada (teste da gota). Em seguida, os catalisadores com melhores desempenhos foram selecionados e testados em um micropropulsor de 2N, onde foram monitorados o empuxo, a pressão e a temperatura da câmara do propulsor. Todos os catalisadores foram caracterizados por Adsorção de Nitrogênio, Termogravimetria, Espectroscopia Fotoeletrônica de Raios-X, Difratometria de Raios-X e Resistência Mecânica à Compressão Radial, visando correlacionar suas propriedades físico-químicas com suas atividades na decomposição catalítica do peróxido de hidrogênio concentrado. Os catalisadores denominados MnAl2 e Co4MnAl, sintetizados pelo método da co-precipitação em solução aquosa, foram aqueles que apresentaram os melhores resultados, sendo capazes de decompor espontaneamente o H2O2 sem sofrer desativação ou fragmentação após os testes.This work aimed to develop mixed oxides, at low cost, to be used as catalysts in the decomposition of hydrogen peroxide, 90% by weight, allowing multiple starts in a microthruster of monopropellant satellites. Different synthesis methods of mixed oxides with high levels of manganese and cobalt oxides were employed. The materials were evaluated, preliminarily, in the spontaneous decomposition of hydrogen peroxide (drop test). Then, the best performing catalysts were selected and tested in a 2N microthruster, where the thrust, the pressure, and temperature in the chamber was monitored. All catalysts were characterized by nitrogen adsorption, thermogravimetry, X-ray photoelectron spectroscopy, X-ray Diffraction, and Mechanical Strength Radial Compression , aiming to correlate their physicochemical properties with their activity in the catalytic decomposition of concentrated hydrogen peroxide.The catalysts called MnAl2 and Co4MnAl, synthesized by co-precipitation in aqueous solution, were those that showed the best results, being able to spontaneously decompose H2O2 without undergoing deactivation or fragmentation after testing.
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Voll, Fernando Augusto Pedersen. "Decomposição do peróxido de hidrogênio sobre catalisadores de paládio." Universidade Estadual do Oeste do Parana, 2008. http://tede.unioeste.br:8080/tede/handle/tede/1868.
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Hydrogen peroxide decomposition is an undesirable reaction in the direct H2O2 synthesis process from H2 and O2. It s a desirable reaction for the generation of hydroxyl radicals (-OH) in the advanced oxidation processes. Thus, it is important to understand how the reaction medium conditions affect the H2O2 decomposition. In this work, the influence of the initial concentration of H2O2, the reaction temperature, the catalyst treatment with H2 and the catalyst deactivation (or activation) with H2O2 were studied. The catalysts studied in this work were a 5% Pd/C, a 0,5% Pd/C, a 1% Pd/g-Al2O3, and a 1% Pd/ZrO2. With the exception of the 1% Pd/ZrO2 catalyst, the apparent reaction rate constant (k) was affected by the initial concentration of H2O2 in the reaction medium, and in all cases where the reaction rate constant (k) was affected, its value decreased with the increase of the initial concentration of H2O2. The activation energy value was calculated for all the catalysts and varied between 25 and 55 kJ/mol. For all the catalysts tested, treatment with hydrogen resulted in a significant increase in the apparent reaction rate constant (k), and in a decrease in the activation energy for the reaction. All the reactions were well represented by a first order rate law. The effect of the treatment with H2O2 (realization of successive reactions of H2O2 decomposition, without catalyst exchange) was studied for the 5% Pd/C and 0,5% Pd/C catalysts (exposed to H2 or not). A small deactivation was observed in the 5% Pd/C catalyst (without prior exposure to H2) after four H2O2 decomposition reactions. A more significant deactivation was observed for the 5% Pd/C and 0,5% Pd/C (both treated with H2). For the 0,5% Pd/C catalyst not exposed to hydrogen, an activation of the catalyst occurred after successive reactions of H2O2 decomposition.
A decomposição do peróxido de hidrogênio é uma reação indesejável no processo de síntese direta do H2O2 a partir do H2 e O2. Por outro lado, é uma reação desejável para a formação dos radicais hidroxila (-OH) nos processos oxidativos avançados. Assim, é importante entender como as condições do meio de reação afetam a decomposição do H2O2. Neste estudo, foi verificada a influência de alguns fatores, tais como a concentração inicial de H2O2, a temperatura de reação, o tratamento do catalisador com H2 e a desativação (ou ativação) do catalisador com H2O2. Os catalisadores estudados nesse trabalho foram 5% Pd/C, 0,5% Pd/C, 1% Pd/γ -Al2O3 e 1% Pd/ZrO2. Com exceção do catalisador 1% Pd/ZrO2, a constante de velocidade aparente (k) da reação foi influenciada pela concentração inicial de H2O2 no meio reacional, e em todos os casos onde a constante de velocidade (k) foi afetada, seu valor diminuiu com o aumento da concentração inicial de H2O2. O valor da energia de ativação foi calculado para todos os catalisadores e variou entre 25 e 55 kJ/mol. Para todos os catalisadores testados, o tratamento com hidrogênio resultou em um aumento significativo no valor da constante de velocidade aparente (k), e em uma diminuição do valor da energia de ativação da reação. Todas as reações foram bem representadas por uma lei de velocidade de primeira ordem. O efeito do tratamento com H2O2 (realização de consecutivas reações de decomposição de H2O2, sem a troca do catalisador) foi verificado nos catalisadores 5% Pd/C e 0,5% Pd/C (tratados com H2 e não tratados). Uma pequena desativação foi observada no catalisador 5% Pd/C (não tratado) depois de algumas reações de decomposição do H2O2. Uma desativação mais significativa foi observada nos catalisadores 5% Pd/C e 0,5% Pd/C (ambos tratados com H2). Para o catalisador 0,5% Pd/C (não tratado com H2), ocorreu uma ativação do catalisador depois de sucessivas reações de decomposição do H2O2.
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Poux, Tiphaine. "Study of the oxygen reduction on perovskite-type oxides in alkaline media." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF001/document.
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La cinétique lente de la réduction de l’oxygène (ORR) est en grande partie responsable de la perte d’énergie de nombreux systèmes de conversion tels que les piles à combustible. Parmi les possibles catalyseurs de l’ORR, les oxydes de type pérovskite sont des candidats prometteurs en milieu alcalin. La présente thèse est consacrée à l’étude de l’activité, du mécanisme et de la stabilité de pérovskites à base de Co et Mn pour l’ORR. Grâce aux techniques d’électrode tournante à disque et disque-anneau (R(R)DE), les études de l’ORR et des transformations d’HO2- sur les couches minces de pérovskite/carbone dans une solution de NaOH ont montré qu’O2 est réduit en OH- via un mécanisme « en série » avec formation d’HO2- intermédiaire. Pour des quantités d’oxyde suffisantes, HO2- est ensuite réduit, ce qui résulte en un mécanisme apparent de 4 électrons. Dans ces électrodes, le carbone joue un double rôle. Il augmente l’activité électrocatalytique en améliorant le contact électrique et il est impliqué dans le mécanisme de l’ORR en catalysant la réduction d’O2 en HO2-, surtout pour les pérovskites à base de cobalt qui sont considérablement moins actives que celles à base de Mn. Néanmoins, l’électrocatalyse de l’ORR semble dégrader les sites actifs des pérovskitesThe sluggish kinetics of the oxygen reduction reaction (ORR) is largely responsible for the energy losses in energy conversion systems such as fuel cells. Among possible inexpensive catalysts for the ORR, perovskite oxides are promising electrocatalysts in alkaline media. The present thesis is devoted to the investigation of the ORR activity, mechanism and stability of some Co and Mn-based perovskites. The rotating (ring) disk electrode (R(R)DE) studies of the ORR and the HO2- transformations on perovskite/carbon thin layers in NaOH electrolyte prove that O2 is reduced to OH- via a “series” pathway with the HO2- intermediate. For high oxide loadings, the formed HO2- species are further reduced to give a global 4 electron pathway. In these electrodes, carbon plays a dual role. It increases the electrocatalytic activity by improving the electrical contact and it is involved in the ORR mechanism by catalyzing the reduction of O2 into HO2-, especially for Co-based perovskites which display lower reaction rates than Mn-based perovskites
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Dakkoune, Amine. "Méthodes pour l'analyse et la prévention des risques d'emballement thermique Zero-order versus intrinsic kinetics for the determination of the time to maximum rate under adiabatic conditions (TMR_ad): application to the decomposition of hydrogen peroxide Risk analysis of French chemical industry Fault detection in the green chemical process : application to an exothermic reaction Analysis of thermal runaway events in French chemical industry Early detection and diagnosis of thermal runaway reactions using model-based approaches in batch reactors." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR30.
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L’histoire des événements accidentels dans les industries chimiques montre que leurs conséquences sont souvent graves sur les plans humain, environnemental et économique. Cette thèse vise à proposer une approche de détection et de diagnostic des défauts dans les procédés chimiques afin de prévenir ces événements accidentels. La démarche commence par une étude préalable qui sert à identifier les causes majeures responsables des événements industriels chimiques en se basant sur le retour d’expérience (REX). En France, selon la base de données ARIA, 25% des évènements sont dus à l’emballement thermique à cause d’erreurs d’origine humaine. Il est donc opportun de développer une méthode de détection et de diagnostic précoce des défauts dus à l’emballement thermique. Pour cela nous développons une approche qui utilise des seuils dynamiques pour la détection et la collecte de mesures pour le diagnostic. La localisation des défauts est basée sur une classification des caractéristiques statistiques de la température en fonction de plusieurs modes défectueux. Un ensemble de classificateurs linéaires et de diagrammes de décision binaires indexés par rapport au temps sont utilisés. Enfin, la synthèse de l'acide peroxyformique dans un réacteur discontinu et semi-continu est considérée pour valider la méthode proposée par des simulations numériques et ensuite expérimentales. Les performances de détection de défauts se sont révélées satisfaisantes et les classificateurs ont démontré un taux de séparabilité des défauts élevésThe history of accidental events in chemical industries shows that their human, environmental and economic consequences are often serious. This thesis aims at proposing an approach of detection and diagnosis faults in chemical processes in order to prevent these accidental events. A preliminary study serves to identify the major causes of chemical industrial events based on experience feedback. In France, according to the ARIA database, 25% of the events are due to thermal runaway because of human errors. It is therefore appropriate to develop a method for early fault detection and diagnosis due to thermal runaway. For that purpose, we develop an approach that uses dynamical thresholds for the detection and collection of measurements for diagnosis. The localization of faults is based on a classification of the statistical characteristics of the temperature according to several defectives modes. A multiset of linear classifiers and binary decision diagrams indexed with respect to the time are used for that purpose. Finally, the synthesis of peroxyformic acid in a batch and semi batch reactor is considered to validate the proposed method by numerical simulations and then experiments. Faults detection performance has been proved satisfactory and the classifiers have proved a high isolability rate of faults
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Cazin, Bernadette. "Contribution à l'étude de générateurs chimiques d'oxygène singulet en solution aqueuse." Paris 6, 1986. http://www.theses.fr/1986PA060049.
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Deux types de générateurs chimiques d'oxygène singulet en milieu aqueux ont été étudiés, en vue d'applications dans les domaines de la biologie et de la synthèse organique. Des substrats naphtaléniques, solubles dans l'eau, permettent de stocker l'oxygène singulet efficacement puisqu'ils fixent (1)O:(2) entre 0 et 20°c, et sont totalement régénérés par thermolyse à 40°c, en libérant l'oxygène dont 50% est à l'état singulet. Ce type de générateur constitue une source douce et "propre" de (1)O(2), permettant l'étude de l'intervention de (1)O:(2) dans les processus biologiques. La "décomposition" de H(2)O(2) par les ions molybdate constitue un moyen pour transformer efficacement H(2)O(2) en oxygène singulet (100%). Sur des considérations cinétiques, nous avons montré que la dismutation s'effectue via l'intermédiaire peroxo MoO(6)(2-). Cette source minérale peut remplacer avantageusement la photo-oxygénation et peut être utilisée pour "charger" en (1)O:(2) les substrats naphtaléniques décrits ci-dessus.
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Mlasi, Bongani. "The decomposition of hydrogen peroxide in acidic copper sulfate solutions." Thesis, 2015. http://hdl.handle.net/10539/17540.
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The effects of copper sulfate on the kinetics of the decomposition of hydrogen peroxide in a sulfuric acid solution were investigated. This was done by measuring the change in temperature as a function of time in a well stirred batch reactor (vacuum flask) immersed in a temperature controlled water bath. The cooling curve when no reaction was taking place was used to determine the heat loss from the reactor. The temperature that was measured during reaction was then corrected to account for heat losses and this corrected temperature profile corresponds to that which would be found in an effectively adiabatic reactor. The corrected temperature is related to the extent of reaction and thus by following the corrected (adiabatic) temperature profile one can monitor the extent as a function of time.
It was found that at lower temperatures (below 58C) the rate of reaction was too slow to measure in the equipment. The reaction rate was sufficiently fast so as to allow accurate measurements of temperatures when the initial temperature was increased to 67C. Unlike what had been expected there was not a single reaction but an exothermic reaction followed by an endothermic reaction. It was shown that both the adiabatic temperature rise and fall were proportional to the amount of hydrogen peroxide added.
The amount of copper sulfate present in the solution affected the exothermic part of the rate of the decomposition of peroxide. However, the amount of copper sulfate had no effect on the rate of the endothermic reaction. A simple model that had an asymptote was chosen to model the effect of the copper sulfate on the rate of the exothermic reaction and it was shown to fit the results very well. A possible explanation for the exothermic reaction followed by the endothermic reaction was proposed.
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Lai, Pei-Lan, and 賴佩嵐. "Decomposition of hydrogen peroxide and mineralization oforganics by Fenton related processes." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/59998416172738193808.
Full textAbstract:
碩士淡江大學
水資源及環境工程學系碩士班
99
The Fenton process is one of the advanced oxidation processes (AOPs) which eliminates organic matter by both hydroxyl radical (OH‧) oxidation and iron salts coagulation. The study was to evaluate the effects of the decomposition of hydrogen peroxide and the mineralization of organics by conducting Fenton-related process. A reactive azo dyestuff (Evecion Red H-E3B, 20 mg/L) and polyvinyl alcohol (PVA, 50 mg/L) were used to simulate color and dissolved organic carbon (DOC) in the industrial textile wastewater which consisted of color of 1200 ADMI unit and DOC of 30 mg/L. The dosages of iron salt, pH, oxidation time as well as dosage of hydrogen peroxide (H2O2) were applied as the operational variables. The capability of the treatment was evaluated by measuring the residual of H2O2 , color unit and DOC. All the experiments were in-beaker tested. The results indicate that the ability to remove color and DOC in Fenton process is at the pH in the order of pH3> pH4> pH2.5. The color removal efficiency works well in pH 2.5, pH 3 and pH 4 under the circumstance of low iron salt dosage. The major mechanism to remove color is oxidation. The dosage of iron salt makes no significant difference in color removal and merely changes the ratio in color removal either by oxidation or coagulation. The iron dosage, however, greatly influences the DOC removal efficiency. Increasing iron salt (Fe2+) dosage enhances greatly on DOC and also improves the coagulation process due to the production of Fe3+ in the treatment. The initial concentration of H2O2 plays a vital role in the oxidation of organic compounds in Fenton process. The optimal dosage of H2O2 is 25 mg/L for color removal as of the oxidation effect. Instead, the excessive amount of H2O2 does not increase the DOC removal since DOC removal is only performed best at some optimum dosage while excessive H2O2 will compete OH‧ with organic matter which retards the oxidation of the organic matter. The oxidation time of 5 minutes reaches the stable status for color and DOC removal, which excessive time period will make no difference.
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Wu, Li-Kai, and 吳立凱. "Thermal Decomposition of Hydrogen Peroxide in the Presence of Sulfuric Acid." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/22735192174998526901.
Full textAbstract:
碩士國立雲林科技大學
環境與安全工程系碩士班
95
Hydrogen peroxide (H2O2) is popularly employed as reaction reagent for the chemical industry and semiconductor plants of chemical cleaning processes. By using the differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), this study focused on the thermal decomposition reaction of H2O2 mixed with sulfuric acid (H2SO4) with low (0.1, 0.5, and 1.0 N), and high concentrations (96 mass%), respectively. Thermokinetic data, such as onset temperature (T0), heat of decomposition (ΔH), and pressure rise rate (dP dt–1), and were obtained and assessed from the DSC and VSP2 experiments. Comparisons of the reactivity of H2O2 mixed with of H2SO4 were assessed to corroborate the reaction of decomposition in these systems. From the reaction of thermal decomposition activity on different concentrations of H2SO4, the experiment data of T0, ΔH, and dP dt-1 were influenced.
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Chung, Pan, and 潘鐘. "Decomposition Kinetics of Hydrogen Peroxide and COD in Leachate Treatment by Fenton Method." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/26921073372077803152.
Full textAbstract:
碩士淡江大學
水資源及環境工程所
82
The object of this thesis was the study of the supernatant after biologically and Fenton''s reagent pretreated leachate . By using the Fenton oxidation , this study explored the rate con- stant of the oxidation of COD and decomposition of Hydrogen Peroxide . Thecontroling factors were dosage of Hydrogen Pero- xide ，Ferrous ions ，Ferric ions and final pH. Through the treatment by Fenton method , the decomposition of both COD and Hydrogen Peroxide showed pseudo first-order reac- tions .In the system of Ferrous ions , the rate constant of the decomposition of Hydrogen Peroxide is obtained as follows : the effect order of Hydrogen Peroxide is -0. 72 and that of Fer- rous ions is 0. 66.As for the decomposition of COD, the effect order of Hydrogen Peroxide is 0.12 and that of Ferrous ions is 0.45.In the system of Ferric ions,the rate constant of decomposi- tion of Hydrogen Peroxide is as follows: the effect order of Hy- drogen Peroxideis -0. 09 and that of Ferric ionsis 0.53. As for the decomposition of COD, the effect order of Hydrogen Peroxide is -0.05 andthat of Ferric ions is 0.42 . The result manifested that the iron ion is the major influe- ncial factor to the rate constant , and the decomposition rate of Hydrogen Peroxide is faster when using Ferrous than using Fe- rric.But when the concentration of iron is low , both rates are similar. When evaluated the removal of COD by Hydrogen Peroxide comsumption , the best dosageof Hydrogen Peroxide is about 600∼800mg/L and that of iron ion is about 300mg/L , which can keep the state that 0.25 gram CODis removed by per gram Hydrogen Per- oxide during the reaction . Besides,the experiment pointed out that chloride is the inhi- bitor to the decomposition of Hydrogen Peroxide. Also, this study offers a solution to the influence of Hydrogen Peroxide upon COD analysis.
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Hsiang, Wang Li, and 王麗香. "Decomposition of Nitrogen-Containing Compounds in Aqueous Solution by UV/Hydrogen Peroxide Process." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/48243064500388052173.
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Tu, Yu-Hsin, and 杜郁欣. "Decomposition of Chlorophenols in Aqueous Solutions by Sonolysis in the Presence of Surfactants and Hydrogen Peroxide." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/42867013044803559728.
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碩士國立臺灣科技大學
化學工程系
91
The objective of this study is to investigate the effect of ultrasound intensity, pH, initial concentration, the presence of hydrogen peroxide and the presence of surfactants on the decomposition of 2-chlorophenol in aqueous solutions by the application of 20 kHz ultrasound. The decomposition rates of chlorophenols were faster for experiments conducted in acidic solutions than those conducted in basic solutions. This is probably because of the predominance of molecular chlorophenols in acidic solution, which are more hydrophobic than ionic chlorophenols, and are more easily decomposed by pyrolysis and by hydroxyl radicals. Because of the electrophilic characteristics of hydroxyl radicals, the attack site of hydroxyl radicals is expected to be the ortho- and para- orientations with Cl and OH group on the molecular structure of chlorophenols. For 3-chlorophenol, there are three points of simultaneous ortho- and para-orientation with Cl and OH groups where hydroxyl radical addition would most easily occur, and 3-chlorophenol is regarded to most readily suffer the addition reaction by hydroxyl radicals. The presence of hydrogen peroxide in reactor solution increased the decomposition rate of chlorophenols and the decomposition of chlorophenols by sonolysis could reach as high as 97 %. Excessive amounts of hydrogen peroxide might react with the hydroxyl radicals and did not contribute to the decomposition of chlorophenols. The presence of surfactants in reactor solution increased the decomposition rate of chlorophenols. However, the presence of exessive surfactants might decrease the decomposition rate of chlorophenols because the surfactants might accumulate on the surface of bubbles to inhibit the transfer of chlorophenol.
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Yang, YuhJoang, and 楊毓中. "Using Adiabatic Calorimeter to Separate Catalytic and Self-Decomposition Reaction Within Hydrogen Peroxide in the Presence of Hydrochloric Acid." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/88849218565409601641.
Full textAbstract:
碩士國立雲林科技大學
環境與安全工程技術研究所
88
In the 1980s, the Accelerating Rate Calorimeter (ARC) made an advance in thermal hazard analysis, because it could record temperature and pressure data more accurately within the region of self-decomposition reaction under approximately adiabatic conditions. Although ways to keep adiabatic conditions may be similar, test cell (bomb) and sensitiveness are not the same in ARC as in other adiabatic calorimeters. However, the operating procedures--Heat-Wait-Search (H-W-S)--are all the same. In this study, an improved operating procedure was used to find the slow first step-catalytic reaction in hydrogen peroxide in the presence of hydrochloric acid. In these two reactions, the hydrochloric acid concentration decreases with the activation energy of the first catalytic reaction and then increases with the activation energy of the second self-decomposition reaction. The temperature at which the catalytic and self-decomposition reaction intersect in the experiment operated by the improved method is the onset temperature of the experiment operated by the standard operating procedure. By the improved operating procedure, the duration of the first catalytic reaction increases with hydrochloric acid concentration being decreased. Operating by the improved method can compensate tmr at the lower temperature (40℃ to onset temperature), which cannot be done by using the standard operating procedure, and can modify the tmr at higher temperature.
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"Kinetic and Mechanism of the Catalysis of the Decomposition of Hydrogen Peroxide by Schiff Base Complexes of Copper(II)." East Tennessee State University, 2004. http://etd-submit.etsu.edu/etd/theses/available/etd-1113104-182005/.
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Wiggins-Camacho, Jaclyn Dawn. "Effect of nitrogen doping on the electronic and catalytic properties of carbon nanotube electrode materials." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-2669.
Full textAbstract:
This dissertation discusses the influence of nitrogen doping (N-doping) on the electronic and catalytic properties of carbon nanotubes (CNTs). These properties have been studied using a variety of techniques, in order to both qualitatively and quantitatively analyze the relationship between the nitrogen concentration and observed properties. Chapter 1 provides a general overview of CNTs and N-doping and details some of the previous research from our group. Chapter 2 discusses the assembly and characterization of free-standing electrode mats, which are used in order to understand the intrinsic physicochemical properties of the material without relying on the secondary influence of another conductive support. Raman microscopy, X-Ray photoelectron spectroscopy, scanning and scanning-tunneling electron microscopy, as well as electrochemical methods were all used to demonstrate the viability of the mat electrodes for further experiments. Chapter 3 addresses the examination of a range of nitrogen concentrations in order to better understand the effects of nitrogen concentration on the electrochemical and electrical properties such as the differential capacitance, density of states at the Fermi level (D(E[subscript F])), bulk conductivity and work function. These properties were studied using a variety of techniques, including UV-photoelectron spectroscopy, electrochemical impedance spectroscopy and conductive four point probe. Chapter 4 investigates the inherent catalysis of the nitrogen doped CNTs (N-CNTs) with respect to O2 reduction, and a complex mechanism is proposed. Electrochemical methods such as cyclic and linear sweep voltammetries as well as thermo-gravimetric analysis and gasometric analysis were all employed to determine heterogeneous decomposition rates as well as to detect intermediates of the O₂ reduction reaction. Chapter 5 discusses the electrocatalytic degradation of free cyanide (CN⁻) at the N-CNT mat electrodes. These results both provide further support for the mechanism discussed in Chapter 4, and present the opportunity for a potential application of N-CNTs for environmental purposes. Specifically, spectroscopic and electrochemical methods, in conjunction with theoretical models show both that the presence of CN⁻ does not inhibit O2 reduction, and that it can be effectively converted to cyanate (OCN⁻) at the N-CNT electrodes. Future work involving the assembly and characterization of transparent N-CNT films is discussed in Chapter 6.text
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"Spectroscopic Examination of the Catalytic Decomposition of Hydrogen Peroxide by a Copper(II) Complex of a Dissymetric Schiff Base and an Imidazole." East Tennessee State University, 2003. http://etd-submit.etsu.edu/etd/theses/available/etd-0715103-171753/.
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