To see the other types of publications on this topic, follow the link: ZrO2-TiO2.
Dissertations / Theses on the topic 'ZrO2-TiO2'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'ZrO2-TiO2.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Andrianainarivelo, Mahandrimanana. "Homogénéité d'oxydes mixtes SiO2-ZrO2, SiO2-TiO2, TiO2-ZrO2, Al2O3-TiO2 et Al2O3-SiO2 préparés par sol-gel non hydrolytiques." Montpellier 2, 1996. http://www.theses.fr/1996MON20077.
Full textAbstract:
Dans ce travail, nous avons prepare des oxydes mixtes: sio#2-zro#2, sio#2-tio#2, tio#2-zro#2, al#2o#3-tio#2 et al#2o#3-sio#2 par un procede sol-gel non hydrolytique base sur la condensation des chlorures metalliques et les alcoxydes metalliques ou entre des chlorures metalliques et des donneurs d'oxygene tels que les ethers. Les rendements en oxydes obtenus apres elimination des groupements organiques residuels sont eleves. Edx et icp nous ont permis de montrer que la composition des oxydes finaux dependait directement de la stoechiometrie des precurseurs. L'homogeneite des gels a ete determinee par leur comportement a la cristallisation et par rmn du #2#9si et ir. Les gels bicomposants obtenus par la voie sol-gel non hydrolytique sont homogenes sauf lorsque le taux de titane est superieur a 8. 5% dans le systeme sio#2/tio#2
2
Dressler, Martina [Verfasser]. "Kristallisationskinetik in TiO2/ZrO2, SnO2/ZrO2 und ZrO2-haltigen LAS-Glaskeramiken mittels der Hochtemperaturröntgenbeugung / Martina Dressler." München : Verlag Dr. Hut, 2012. http://d-nb.info/102878533X/34.
Full text
3
Kratschmer, Tim. "Flammgespritzte Schichten im System Al2O3-TiO2-ZrO2." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-63845.
Full textAbstract:
Beim Flammspritzen von Mischungen im System Al2O3-TiO2-ZrO2 treten vielfältige Effekte auf. Es kommt z.B. zur Ausbildung eines amorphen Anteils, der in Form von amorphen Sublamellen, dem primären amorphen Anteil, und in dendritisch geprägten Bereichen, dem sekundären amorphen Anteil im Gefüge vorliegt. Dieser beeinflusst die mechanischen Eigenschaften deutlich. Bei einer Temperaturbehandlung entstehende Ausscheidungen von ZrO2 oder verschiedenen Zirkoniumtitanaten beeinflussen die mechanischen Eigenschaften ebenfalls signifikant.
4
Silva, P. D. G. "Síntese e caracterização do core-shell ZrO2:Y3+@TiO2." Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/6453.
Full textAbstract:
Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-10-27T16:02:50Z
No. of bitstreams: 2
Dissertação - Paula Daiany Gonçalves Silva - 2016.pdf: 5020325 bytes, checksum: 7a70eccab776cc3598c1f6236a35273d (MD5)
license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-11-07T13:53:03Z (GMT) No. of bitstreams: 2 Dissertação - Paula Daiany Gonçalves Silva - 2016.pdf: 5020325 bytes, checksum: 7a70eccab776cc3598c1f6236a35273d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
Made available in DSpace on 2016-11-07T13:53:03Z (GMT). No. of bitstreams: 2 Dissertação - Paula Daiany Gonçalves Silva - 2016.pdf: 5020325 bytes, checksum: 7a70eccab776cc3598c1f6236a35273d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-21
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Since the early 90's researchers have investigated the combination of nanocomposites comprised of multilayers, which have better efficiency than their corresponding individual particles, may present in certain cases, new properties. The resulting structure is called a core-shell. In this study, were synthesized ZrO2:Y 3+ coated with TiO2, obtaining nanocomposites ZrO2:Y 3+ @TiO2 with a thickness of 10, 20 and 50% shell. The photoluminescent property (FL) of the nanocomposites was studied. Such interest is due to the fact that the order/disorder structural at the interface of the core-shell type systems may be possible recombination processes responsible for the photoluminescence emission of these materials. Nanoparticles of the core and the shell were obtained by the Method of Polymeric Precursors. The samples were characterized by X-ray diffraction (XRD) to identify the formation of the nanocomposite and evaluate the structural order in the synthesized materials. The core was obtained with tetragonal structure and the shell with anatase structure. From the diffractograms have been carried out calculations of the crystallite size and lattice parameters. The characterization by Transmission Electron Microscopy (TEM), it was not possible to differentiate the core of the shell by the images, since both are structurally ordered, requiring analysis by Energy Dispersive X-ray (EDX), which was verified the presence of Zr and Ti elements that comprise the core-shell nanocomposite. The FL emission results were explained as a function of the shell thickness, as well as the effect of calcination temperature on the order-disorder structural material. To evaluate the performance of the FL issuing nanocomposites were calculated chromaticity coordinates, based on the FL emission spectra.
Desde o início da década de 90 pesquisadores vêm investigando a combinação de nanocompósitos constituídos por multicamadas, os quais apresentam melhor eficiência do que suas partículas individuais correspondentes, podendo apresentar em alguns casos, novas propriedades. A estrutura obtida é denominada core shell. No presente trabalho, foram sintetizados ZrO2:Y 3+ recobertos com TiO2, obtendo nanocompósitos ZrO2:Y 3+ @TiO2 com espessura de 10, 20 e 50% de shell. Foi estudada a propriedade fotoluminescente (FL) dos nanocompósitos. Tal interesse deve-se ao fato de que a ordem/desordem estrutural na interface dos sistemas do tipo core-shell pode ser possibilitar processos de recombinação responsáveis pela emissão fotoluminescente destes materiais. As nanopartículas do core e do shell foram obtidos pelo Método dos Precursores Poliméricos. As amostras foram caracterizadas por difração de Raios X (DRX) a fim de se identificar a formação do nanocompósito e avaliar a ordem estrutural nos materiais sintetizados. O core foi obtido com estrutura tetragonal e o shell com estrutura anatase. A partir dos difratogramas foram realizados cálculos do tamanho de cristalito e parâmetros de rede. Na caracterização por Microscopia Eletrônica de Transmissão (MET), não foi possível diferenciar o core do shell pelas imagens, uma vez que ambos encontram-se estruturalmente ordenados, sendo necessária a análise por Energia Dispersiva de Raios X (EDX), na qual verificou-se a presença dos elementos Zr e Ti que compõem o nanocompósito core-shell. Os resultados de emissão FL foram explicados em função da espessura do shell, bem como pelo efeito da temperatura de calcinação na ordem-desordem estrutural do material. Para avaliar o desempenho da emissão FL dos nanocompósitos foram calculadas as coordenadas de cromaticidade, baseado nos espectros de emissão FL.
5
Konishi, Junko. "Studies on functional TiO2 and ZrO2 monoliths with controlled porous structures." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136298.
Full text
6
Modesto, Junior Olayr. "Caracterização e aplicação fotocatalítica de compósitos óxidos TiO2/CuO, TiO2/ZnO E TiO2/ZrO2 sintetizados pelos processos Sol-gel e Poliol. /." Bauru, 2018. http://hdl.handle.net/11449/158268.
Full textAbstract:
Orientador: Dayse Iara dos SantosResumo: O desenvolvimento de materiais cerâmicos é um campo de pesquisa cujos resultados são extremamente promissores para aplicações tecnológicas. Particularmente, no caso dos materiais nanoestruturados baseados no óxido titânio, observa-se grande potencial de aplicação em dispositivos optoeletrônicos, bem como, para processos de fotocatálise, visto que apresenta um bandgap direto de 3,2 eV. Além disso, o aperfeiçoamento das propriedades ópticas, por meio da interação entre óxidos de diferentes bandas eletrônicas, têm sido estudado por muitos autores. Por esta razão, compósitos nanoestruturados formados de dois ou mais óxidos, cujas propriedades são distintas quando isolados, têm sido sintetizados juntos e caracterizados a fim de avaliar possíveis interações sinérgicas. Neste trabalho, foram preparados e caracterizados os compósitos TiO2/CuO, TiO2/ZnO e TiO2/ZrO2. As sínteses foram realizadas pelo método Sol-gel original e pelo método Poliol modificado, e ambos os processos se mostraram propícios para a obtenção de nanocompósitos e óxidos nanoparticulados. O método Poliol produziu compósitos formados de partículas micrométricas de dióxido de titânio revestidas do segundo óxido, enquanto o processo Sol-gel resultou em material constituído de agregados de nanocristais com alta mesoporosidade. Por meio da difração de raios X dos pós tratados gradualmente até 1000 °C observou-se que a formação e cristalização dos óxidos ocorrem em temperatura mais alta quando o material é resultante do ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The development of ceramic materials is a field of research whose results are extremely promising for technological applications. Particularly, in the case of nanostructured materials based on titanium oxide, there is a great potential for application in optoelectronic devices, as well as for photocatalysis processes, since it has a direct bandgap of 3.2 eV. In addition, the improvement of the optical properties through the interaction between oxides of different electronic bands has been studied by many authors. For this reason, nanostructured composites formed of two or more oxides, whose properties are distinct when isolated, have been synthesized together and characterized in order to evaluate possible synergistic interactions. In this work the TiO2 / CuO, TiO2 / ZnO and TiO2 / ZrO2 composites were prepared and characterized. The syntheses were carried out using the original Sol-gel method and the modified Polyol method, and both processes proved to be suitable for nanocomposites and nanoparticulate oxides. The polyol method produced composites formed of micrometric titanium dioxide particles coated with the second oxide, while the sol-gel process resulted in material composed of nanocrystalline aggregates with high mesoporosity. By X-ray diffraction of the powders gradually treated to 1000 °C it was observed that the formation and crystallization of the oxides occur at a higher temperature when the material is produced by the Sol-gel process. With the observation of the ... (Complete abstract click electronic access below)
Doutor
7
FERREIRA, Katiúscia Daiane. "ESTUDO DE FASES E CRESCIMENTO DE MONOCRISTAIS NO SISTEMA Bi2O3 - TiO2 - ZrO2." Universidade Federal de Goiás, 2008. http://repositorio.bc.ufg.br/tede/handle/tde/1044.
Full textAbstract:
Made available in DSpace on 2014-07-29T15:12:45Z (GMT). No. of bitstreams: 1
dissertacaokatiusciaDaia.pdf: 861870 bytes, checksum: 844752d18d747dab701abe725ec66d0d (MD5)
Previous issue date: 2008-08-18I n this work a systematic study on the phase formation and stability in the system Bi2O3-ZrO2 was realized, the solubility of the Zr4+ ion in Bi12TiO20 (BTO) was investigated and Zr-doped BTO crystals (BTO:Zr) were grown and optically characterized. It was verified that a tetragonal phase was formed in the following wide composition interval: (6-x)Bi2O3:(1+x)ZrO2, with x = 0.5, 0.3, 0.2, 0.1, 0, -0.1, -0.2, -0.3, -0.5, -0.65 e -0.7. The phases were synthesized by solid state reaction and the powders were characterized by Xray diffraction and diferential thermal analysis. The formed tetragonal phase, however, was metastable for all investigated compositions and its preparation was dependent on the sample thermal history. The stable phase at room temperature was a monoclinic one. A low solubility of Zr4+ in BTO was verified, but BTO:Zr single crystals were grown by Top Seeded Solution Growth (TSSG) technique. Good quality crystalline samples were prepared and characterized by chemical compositon and by optical activity, photoconductivity and electro-optical measurements. The results shown that Zr-doping produced a decreasing in the crystal photosensitivity, and almost no changes in the optical activity and electro-optical coefficient were generated.
Neste trabalho foi realizado um estudo sistemático das condições de preparação e estabilidade de fases no sistema Bi2O3-ZrO2, a solubilidade do íon Zr4+ no Bi12TiO20 (BTO) foi investigada e cristais de BTO dopados com Zr4+ (BTO:Zr) foram crescidos e caracterizados opticamente. Verificou-se que uma fase tetragonal é formada no amplo intervalo de composições (6- x)Bi2O3:(1+x)ZrO2, com x = 0,5, 0,3, 0,2, 0,1, 0, -0,1, -0.2, -0,3, -0,5, -0,65 e - 0,7. As fases foram sintetizadas por reação no estado sólido e os pós foram caracterizados por difração de raios-X e análise térmica diferencial. A fase tetragonal formada, no entanto, é metaestável em todo o intervalo de composições investigadas, sendo sua obtenção condicionada à história térmica da amostra. A fase estável à temperatura ambiente é monoclínica. Foi constatado que a solubilidade do Zr4+ no BTO é baixa, mas cristais de BTO:Zr foram crescidos através da técnica Top Seeded Solution Growth (TSSG). Amostras cristalinas de boa qualidade óptica e estrutural foram preparadas e caracterizadas quanto à composição química e através de medidas de atividade óptica, fotocondutividade e coeficiente eletro-óptico. Os resultados demonstram que o Zr produz uma diminuição na fotosensibilidade do cristal, provocando pouca alteração nos valores de atividade óptica e coeficiente eletro-óptico
8
Angulo, Pedoro Antonio Diaz. "Microstructural characterization of a plasma sprayed ZrO2-Y2O3-TiO2 thermal barrier coating." Thesis, Brunel University, 1996. http://bura.brunel.ac.uk/handle/2438/6293.
Full textAbstract:
The use of plasma sprayed ceramic coats as thermal barrier coatings (TBCs) for the protection of metallic structures and equipment from severe thermal, abrasive and corrosive conditions has been documented extensively in the last two decades. The state-of-the-art TBCs consist of a double layer coat. a top ceramic layer and an intermediate bond coat (MCrAIY, M=Ni, Co, Fe) deposited on the alloy substrate. Zirconia, both stabilized and partially stabilized with different oxides has been used as the ceramic top coat due to its low thermal conductivity and low thermal expansion coefficient. Studies of the microstructure of the TBCs have shown aspects that can help the understanding of the properties of the coating. The ternary system ZrOz-Y203-TiCz is believed to offer improved properties when it is compared to Zr02-Y203. However, the use of &02-Y203-Ti02 as TBCs, a major part of this work, is not widely reported in the literature. The purpose of this thesis was to study the microstructure of a plasma sprayed ZrOrY203-TiO2 TBC using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Transmission Electron Microscopy (TEM). The evolution of the Zr41_phase distribution in the ceramic coat was followed by XRD after different heat treatments, with the finding that the cooling rate plays a decisive role in the final Zr42 phase composition. SEM studies allowed a description of the lamellae structure of the Zr02-Y203-TiOz coating. The evolution of the morphology, porosity and crack distribution in the coat after different thermal treatments were followed by SEM. Evidence of incipient sintering is observed in Zr02-Y203-Ti02 coats heated at temperatures higher than 1200 °C. This should lead to poor coating performance. EDS analysis revealed an heterogeneous distribution of titanium through the oating. A detailed microstructural characterization of the as-sprayed coating was done using TEM. Microstructural features such as micro-twins, antiphase-boundaries and mottled morphology associated with "non-transformable" tetragonal ZrO2 phase were identified. It is believed that these microstructural elements promote toughening and thermal stress relief mechanisms that provide the coating with the erosion and thermal shock resistance required for a TBC. The presence of TiO2 is linked to a higher proportion of tetragonal ZrO2 in the Zr02-Y203-Ti02 coating, therefore improved properties of the coating are expected. The addition of TiO2 promotes grain growth and decreases the final density in pressed and sintered Zr02-Y203-TiO2 powders. The results obtained are a contribution to the understanding of the microstructure of TBCs and to the sparse knowledge base of the ZrOrY2O3-TiO2 coatings. Further work should be done in the characterization of the ZrO2-Y2O3-Ti42 coatings and the study of its stability under different conditions in order to determine the real potential of this material offers as an alternative to the better known ZrOrY203 TBC.
9
Lahcene, Driss. "Synthèse et caractérisation des oxydes mixtes type MxOy-TiO2 (M = V, Zr et Si) par voie sol-gel. Application à l'époxydation du cyclohexène." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2263.
Full textAbstract:
L'objectif de ce travail est : (i) pour préparer des oxydes mixtes X% MxOy-TiO2 (M = V, Zr et Si), (X = 5, 10, 15 et 20 wt-.% MxOy.) par la méthode sol-gel et suivie par une calcination à 500° C, (ii) de caractériser les échantillons préparés par différentes méthodes d'analyse physico-chimique (AAF, ICP, DRX, BET, TG-DTA et FT-IR) et (iii) d'étudier leur réactivité dans l'époxydation de cyclohexène.D'après les résultats des caractérisations, nous constatons que :- L'analyse DRX montre que pour les trois systèmes nous avons l'apparition de la phase anatase de TiO2. La meilleure cristallinité a été observée pour le système en présence de V2O5. La phase de SiO2 est amorphe et la phase de ZrO2 n'a pas été détectée.- L'analyse par adsorption d'azote, donne le classement de ces systèmes selon leurs surfaces spécifiques comme suit :SiO2-TiO2>ZrO2-TiO2>V2O5-TiO2- L'analyse FT-IR de l'adsorption de la pyridine in situ montre que les trois systèmes présentent des sites acides de Lewis, alors que le 15%V2O5-TiO2 présente en plus les sites de Brönsted.Nous avons étudié aussi l'influence de divers paramètres expérimentaux sur la réaction d'époxydation du cyclohexène. Les résultats des tests catalytiques montrent que :- Les meilleurs résultats sont obtenus pour le système V2O5-TiO2.- Les meilleurs solvants sont l'heptane et l'acétonitrile qui donnent une bonne activité catalytique et une bonne sélectivité en époxyde.- La réaction d'époxydation du cyclohexène est une réaction du second ordre.- Le catalyseur 20% V2O5-TiO2 est stable au cours de la réaction catalytique et recyclableThe aim of this work is: (i) to prepare mixed oxides X%MxOy-TiO2 (M = V, Zr and Si), (X = 5, 10, 15 and 20 wt.-% MxOy) by sol-gel method followed by calcination at 500°C, (ii) to characterize the prepared samples by different methods of physicochemical analysis (AAF, ICP, XRD, BET, TG-DTA and FT-IR) and (iii) to study their reactivity in the epoxidation of cyclohexene. According to the characterization results, we found that:- The XRD analysis shows that, for the three systems, TiO2 anatase has been evidenced. The best crystallinity was observed for the V2O5-TiO2 system. The TiO2 rutile phase has been obeserved for sample 5% ZrO2-TiO2, while the SiO2 phase is amorphous and ZrO2 phase was not detected.- Analysis by nitrogen adsorption, gave the sorting of these systems according to their specific surface areas as follows: SiO2-TiO2 > ZrO2-TiO2 > TiO2-V2O5- The FTIR analysis of in situ pyridine adsorption showed that all three systems display Lewis acid sites, whereassample 15% V2O5-TiO2 present Bronsted sites too.We studied the effect of different reaction parameters in the oxidation of cyclohexene. The results of the catalytic tests show that:- The best results are obtained for V2O5-TiO2 system.- The best solvents are heptane and acetonitrile which give good catalytic activity and high epoxide selectivity.- The epoxidation reaction of cyclohexene is a second-order reaction.- The catalyst 20%V2O5-TiO2 is stable during the catalytic reaction and suitable for recycling
الهدف من هذا العمل هو تحضير أكاسيد المختلطةX%MxOy-TiO2, (M = V, Zr et Si), (X = 5, 10, 15 et 20 %) ، حيث X هو نسبة كتلة MxOy. تشخيص ودراسة نشاطها في اكسدة الهكسن الحلقي بوجود (TBHP) في الطور السائل. تم تحضير هذه أكاسيد المختلطة بطريقة sol-gel و حرقها تحت درجة حرارة 500 وتشخص هذه المواد بطرق مختلفة من التحليل الفيزيائية و الكيميائية (AAF, ICP, DRX, BET, ATG-ATD et FT-IR)وفقا لنتائج التشخيص نستخلص مايلي:-التحليل DRX تبين أن الأنظمة الثلاثة لديها طور anatase TiO2 ولوحظ أفضل التبلور في وجود نظام V2O5. وقد وجد طور rutile من TiO2 عن عينة 5%ZrO2-TiO2، في حين أن طور SiO2 غير متبلور ولم يتم الكشف طور ZrO2- تحليل عن طريق امتزاز النيتروجين BET ويعطي تصنيف هذه النظم حسب المساحة المحددة على النحو التالي:SiO2-TiO2> ZrO2-TiO2> TiO2-V2O5- أظهر تحليل FTIR بامتصاص بيريدين أن جميع الأنظمة الثلاثة لديها مواقع حمض لويس، في حين أن15%V2O5-TiO2 لديه بالإضافة مواقع برونستيد.درسنا أيضا تأثيرعدة عوامل التجريبية على تفاعل اكسدة الهكسن الحلقي بما في ذلك تأثير المذيب، كتلة المحفز، دراسة استقرار المحفز ودراسة الحركية التفاعل لتحسين المردودية و الانتقائية لإيبوكسيد.نتائج التفاعل المحفز تظهر أن:- تم الحصول على أفضل النتائج بوجود النظام V2O5-TiO2- أفضل المذيبات هي هيبتان والأسيتونيتريل لإعطاء فعالية جيدة وانتقائية عالية لإيبوكسيد.- تم الحصول على أفضل النتائج في حالة 100 و 150 ملغ مع تحويل 46 و 53٪ على التوالي. ولوحظ ان أفضل الانتقائية لإيبوكسيد (79٪) سجلت عند 100 ملغ من20 % V2O5-TiO2.رتبة تفاعل اكسدة الهكسن الحلقي في وجود 150 ملغ من 20 % V2O5-TiO2هي رتبة اثنين. المحفز 20 % V2O5-TiO2 هو مستقر خلال تفاعل تحفيز ومناسبة لإعادته عدة مرات.كلمات المفتاحية: سول جل، أكاسيد المختلطة، أكسدة الهكسن الحلقي، أوكسيد الهكسن الحلقي V2O5-TiO2, ZrO2-TiO2, SiO2-TiO2
10
Castelblanco, William Nova. "Redução de NO com CO sobre catalisadores de CuO, Fe2O3 e CuO-Fe2O3 suportados em TiO2, ZrO2 e TiO2-ZrO2: Efeito do vapor de água na atividade e seletividade a N2." Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/4124.
Full textAbstract:
Made available in DSpace on 2016-06-02T19:56:52Z (GMT). No. of bitstreams: 1
5331.pdf: 11740082 bytes, checksum: e8f5288e8c937187089b53d5c0ebd1c9 (MD5)
Previous issue date: 2013-04-26Financiadora de Estudos e Projetos
The combustion of petroleum fuels produces large emissions of NOX, SOX and other strong atmospheric pollutants. The abatement of NOX can be achieved by the nonselective catalytic reduction of NO with CO, for that, supported noble metals have been the most commonly used, with high cost as disadvantage. Transition metal oxides show good activity for this reaction, however, they have poor performance in the presence of SO2, O2 and water steam. Thus, this study aimed to prepare, characterize and evaluate catalysts based on CuO, Fe2O3 and CuO-Fe2O3 supported on TiO2, ZrO2 and their mixtures, in the reduction of NO to N2 with CO in the presence or absence of water steam. XRD data, N2 adsorption and H2-TPR showed that mixed oxides and their catalysts, prepared by sol-gel in-situ, presented specific surface areas between 30 to 60 m2/g, with Cu or Fe species highly distributed, having the last greater interaction with titanium. Rietveld refinement showed preferential formation of zirconium titanate, then showing a close interaction of these species in the mixed supports. All catalysts were highly active in the reduction of NO to N2. At temperatures below 500 °C a CuO catalysts were more active and selective for the formation of N2 than Fe2O3, with the formation of N2O being favored with the increase of zirconium in the support. At 600 °C, the high conversion of NO to N2 on CuO was not influenced by the content of TiO2 in the support. Also at 600 °C, an increasing in the content of titanium in the Fe2O3 catalysts resulted in a significant drop in the conversion of NO to N2. The presence of water steam during the reduction of NO with CO at 600 °C caused a significant decrease in the conversion of NO to N2 and CO to CO2 on the CuO catalyst on the support with higher titanium content. The water steam completely eliminates the activity for the reduction of NO to N2 on Fe2O3 catalysts, but keeping a high conversion of CO to CO2. The CuO and CuO-Fe2O3 catalysts on zirconium-rich supports showed high potential for the abatement of NOX in the presence of water steam at temperatures above 500 ºC.
A combustão de derivados do petróleo gera grandes emissões de NOX, SOX e outros fortes poluentes da atmosfera. O abatimento de NOX pode ser realizado por meio da redução catalítica não seletiva com CO, onde os metais nobres suportados têm sido os mais empregados, com a desvantagem de seu elevado custo. Óxidos de metais de transição apresentam boa atividade nessa reação, no entanto, têm baixo desempenho na presença de SO2, O2 e vapor de água. Assim, este trabalho teve como objetivo preparar, caracterizar e avaliar catalisadores a base de CuO, Fe2O3 e CuO-Fe2O3 suportados em TiO2, ZrO2 ou suas misturas, na redução de NO a N2 com CO na presença ou ausência de vapor de água. Dados de DRX, adsorção de N2 e RTP-H2 mostraram que os suportes mistos e seus catalisadores, que foram preparados via síntese sol-gel in-situ, apresentaram áreas superficiais específicas entre 30 e 60 m2/g, com as espécies de Cu ou Fe altamente distribuídas, tendo essas últimas maior interação com a titânia. Refinamento de Rietveld mostrou formação preferencial de titanato de zircônia, evidenciando a estreita interação dessas espécies nos suportes mistos. Todos os catalisadores foram altamente ativos na redução de NO a N2. Em temperaturas inferiores 500 ºC os catalisadores de CuO foram mais ativos e seletivos à formação de N2 que o Fe2O3, com a formação de N2O sendo favorecida com o aumento de zircônia no suporte. A 600 ºC, a alta conversão de NO a N2 sobre CuO não foi influenciada pelo conteúdo de TiO2 no suporte. Nessa temperatura, o aumento do teor de titânia provocou nos catalisadores de Fe2O3 uma queda significativa na conversão de NO a N2. A presença de vapor de água durante a redução de NO com CO a 600 ºC provocou sobre CuO queda significativa da conversão de NO a N2 e de CO a CO2 sobre o suporte com maior conteúdo de titânia. Nos catalisadores de Fe2O3 puro, o vapor de água anulou completamente a atividade para a redução de NO a N2, mas manteve-se a conversão de CO a CO2. Os catalisadores de CuO e CuO-Fe2O3 sobre suporte contendo alto teor de zircônia apresentaram alto potencial para o abatimento de NOx na presença de vapor de água em temperaturas superiores a 500 ºC.
11
Cassidy, James. "Parsing The Aggregation- and Photodegradation-Induced Effects of Rhodamine-Sensitized Tio2 and Zro2 Films." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1499450063.
Full textAbstract:
The impact of rhodamine aggregates on the photophysical properties of rhodamine dyes adsorbed to TiO2 were investigated using diffuse reflectance spectroscopy, steady-state fluorescence, and time-correlated single photon counting (TCSPC). Photocatalyzed de-alkylation of rhodamine dyes containing tertiary amine groups (5-ROX, R101, and RB) was observed on TiO2, which resulted in a ~50 nm hypsochromic shift. Therefore, concentration dependent diffuse reflectance spectra of R560/TiO2 samples, which contained primary amines, demonstrated the formation of H- and J-aggregates at the expense of the monomers. The formation of J-aggregates resulted in FRET between monomers and J-aggregates which yielded a bathochromic shifted fluorescence spectra as a function of increased dye concentration. Additionally, the J-aggregates were believed to be less fluorescent than the corresponding monomer, which, in addition to the presence of non-fluorescent H-aggregates, led to the quenched fluorescence. Time dependent fluorescent measurements established that electron injection to TiO2 from R560 occurred from both the monomer and J-aggregates, as lifetimes of each species on TiO2 were quenched relative to lifetimes on ZrO2.
12
Le, Phuong Thu. "Oxydation en voie humide des effluents des distilleries d'alcool à partir de canne à sucre en présence de catalyseurs Ru et Pt supportés sur TiO2 ou ZrO2." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10203/document.
Full textAbstract:
La vinasse est un effluent aqueux issu des distilleries d'éthanol produit à partir de mélasse de canne à sucre, caractérisé par une couleur intense, une forte Demande Chimique en Oxygène (DCO) et un faible Demande Biologique en Oxygène (DBO). Le traitement de ce type d'effluent par Oxydation en Voie Humide (OVH) a fait l'objet d'une étude sur catalyseurs métaux nobles supportés sur TiO2 ou ZrO2 à 190-210°C sous 50-70 bar d'air. L'addition de catalyseurs au Ru permet la minéralisation complète de la partie carbone des polluants modèles (saccharose, polyéthylène glycol, mélanoïdine) ou des effluents réels (vinasse de Cognac et vinasse de canne); les catalyseurs au Pt sont également très efficaces, mais ne convertissent que très peu l'acide acétique formé intermédiairement. Dans ces conditions, l'azote sous forme organique est converti en ammonium. Alors qu'en l'absence de catalyseur, les ions ammonium sont stables, l'addition d'un catalyseur est capable de convertir l'ammonium en diazote et nitrate. Les sélectivités relatives en N2 et NO3 - dépendent des conditions oxydantes de la réaction (quantité d'azote à traiter par rapport à la quantité de métal actif). De manière générale, le platine se révèle plus sélectif en diazote. Une lixiviation des métaux a été détectée au démarrage des réactions d'OVHC des effluents à cause de l'azote sous forme organique ; elle diminue et disparaît au fur et à mesure de la minéralisation de l'azote et le métal se redépose sur le solide catalytique. Les essais en réacteur continu confirment les observations en réacteur batchVinasse is an aqueous effluent originating from ethanol production process from sugarcane. It is a dark brown effluent with an extremely high COD and a low BOD. The treatment of this type of effluent by wet air oxidation (WAO) was the subject of this study using noble metal catalysts supported on TiO2 and ZrO2 at 190-210 ° C under 50-70 bar air. The addition of Ru catalysts allowed the complete mineralization of the organic model pollutants (sucrose, polyethylene glycol, melanoidin) or the real effluents (cognac vinasse and cane vinasse); the Pt catalysts were also very effective, but acetic acid was formed as an intermediate which was difficult to be converted. Under these conditions, the organic nitrogen was converted to ammonium. Whereas in the absence of catalyst, the ammonium ions were stable, the addition of a catalyst was capable of converting ammonium to dinitrogen and nitrate. The selectivity to N2 and NO3 - depended on the oxidizing reaction conditions (molar ratio nitrogen/metal). In general, platinum proved to be more selective to dinitrogen. Metal leaching was detected upon CWAO of effluents containing organic nitrogen. The leaching decreased and disappeared as nitrogen was mineralised and the dissolved metal redeposited on the solid catalyst. The continuous reactor tests confirmed the observations in the batch reactor
13
Hosseini, Mahsa. "Etude de catalyseurs Pd/Au déposés sur oxydes poreux, TiO2 et TiO2-ZrO2, hautement structurés vis-à-vis de l'oxydation des Composés Organiques Volatils (COV)." Littoral, 2008. http://www.theses.fr/2008DUNK0226.
Full textAbstract:
Au cours de ce travail de thèse, des catalyseurs supportés à base de palladium et/ou or ont été synthétisés par imprégnation et déposition sur des supports TiO2 mésoporeux et oxydes mixtes TiO2-ZrO2 macro-mésoporeux hautement structurés (avec des rapports molaires Ti/Zr de 80/20, 50/50 et 20/80). Les caractérisations physico-chimiques des catalyseurs synthétisés ont été effectuées par une série de techniques telles que l’adsorption-désorption d’azote, la Réduction en Température Programmée, la Diffraction de Rayons X, les Spectroscopies Infra Rouge et UV-Visible en Réflexion Diffuse et l’Analyse Thermique. La performance catalytique des matériaux nanostructurés a été testée dans l'oxydation totale du toluène et du propène dans un microréacteur fixe et par IRTF en réflexion diffuse «operando». Quel que soit le support, le système Pd-Au déposé est un catalyseur très actif dans la réaction d’oxydation des COV. Pour les catalyseurs à base de TiO2-ZrO2 (TZ), l’activité catalytique varie en fonction du rapport molaire Ti/Zr. La plus grande activité de PdAu/TZ 80/20 peut être reliée à une plus grande teneur en Ti et aussi à la présence d’un effet de synergie entre le palladium et l’or. La réaction catalytique suivie par IR «operando» a permis de suivre l’oxydation des COV mais aussi l’adsorption de la molécule à oxyder qui augmente dans l’ordre inverse de l’activité catalytiqueTwo nanostructured materials have been synthesized : mesoporous TiO2 and macromesoporous TiO2-ZrO2 mixed oxides with various Ti/Zr mole ratios of 80/20, 50/50 and 20/80. These solids present a well defined macro-mesoporous structure and a high specific surface. The supports were all impregnated by 0. 5 or 1. 5wt% of palladium and 1wt% of gold. Gold was deposited using Deposition-Precipitation method and a solution containing HauCl4. Palladium supported samples were prepared by aqueous impregnated method using palladium nitrate. The solids obtained were all characterized by transmission electron microscopy, thermal analysis, specific areas measurements, X-ray diffraction, H2 temperature programmed reduction, electron paramagnetic resonance and diffuse reflectance UV-Visible spectroscopy. The catalysts were tested for toluene and propene total oxidation in a conventional fixed bed micro reactor and with “operando” Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy in which H2O and CO2 were found to be the only products at total conversion. Depending on the order of the deposition of the palladium and gold, the Pd-Au/Porous material sample shows significantly a higher conversion in comparison with the Au-Pd/Porous material sample. The best activity for Pd-Au/Porous material can be explained by a core-shell morphology with a gold-rich core and a palladium-rich surface and the less activity of Au-Pd/Porous material by an inverse core-shell. For the TiO2-ZrO2, whatever the impregnated active phase, the more the Ti/Zr ratio the more the activity for toluene and propene total oxidation. “Operando” DRIFT allowed following the VOC oxidation but also siggesting a adsorption of the VOCs molecules which increases in the same order than he activity for oxidation reaction
14
Klettlinger, Jennifer Lindsey Suder. "Fischer-Tropsch Cobalt Catalyst Improvements with the Presence of TiO2, La2O3, and ZrO2 on an Alumina Support." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1333981467.
Full text
15
Quirino, Rafael Lopes. "Estudo do efeito da presença de alumina dopada com TiO2 e ZrO2 no craqueamento do óleo de soja." reponame:Repositório Institucional da UnB, 2006. http://repositorio.unb.br/handle/10482/18560.
Full textAbstract:
Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2006.Submitted by Amanda Esteves Silva (amandasilva@bce.unb.br) on 2015-10-06T15:51:53Z No. of bitstreams: 1 2006_Rafael Lopes Quirino.pdf: 386186 bytes, checksum: c506316ee91e3ced47c67817af8444b6 (MD5)
Approved for entry into archive by Marília Freitas(marilia@bce.unb.br) on 2015-10-06T15:54:05Z (GMT) No. of bitstreams: 1 2006_Rafael Lopes Quirino.pdf: 386186 bytes, checksum: c506316ee91e3ced47c67817af8444b6 (MD5)
Made available in DSpace on 2015-10-06T15:54:05Z (GMT). No. of bitstreams: 1 2006_Rafael Lopes Quirino.pdf: 386186 bytes, checksum: c506316ee91e3ced47c67817af8444b6 (MD5)
O craqueamento catalítico de triacilglicerídeos se apresenta como uma alternativa viável para a produção de biocombustíveis com baixa emissão de poluentes. Apresenta-se aqui um estudo sobre a utilização de sólidos, formados a base de óxidos mistos de Ti, Zr e Al, como catalisadores na reação de pirólise do óleo de soja. O estudo contempla, após uma ampla revisão bibliográfica sobre o processo de obtenção de hidrocarbonetos a partir de triacilglicerídeos por pirólise de óleos vegetais e gorduras animais, a síntese por coprecipitação e a caracterização dos diversos sólidos por análise termogravimétrica, difração de raios-X, área superficial determinada pelo método BET, composição química (ICP-AES), espectroscopia Raman e determinação da acidez superficial por titulação e FTIR. Os produtos obtidos no craqueamento de óleo de soja foram analisados por destilação, índice de acidez, espectroscopia no infravermelho, densidade, viscosidade, resíduo de carbono, determinação do índice de cetano e caracterização da mistura resultante por CG-MS e CG-FID. A análise dos produtos obtidos na presença e na ausência dos óxidos sintetizados permitiu concluir que todos os sólidos testados apresentaram atividade catalítica para a desoxigenação dos produtos finais apenas na segunda etapa do processo de craqueamento. ______________________________________________________________________________________________ ABSTRACT
The catalytic cracking of triglycerides presents itself as a possible alternative to the production of biofuels with low emission of pollutants. In this work a study of the use of solids, constituted by mixed oxides of Ti, Zr and Al, as catalysts for the cracking reaction of soybean oil is presented. The study involves, after a large bibliographic review about the obtention of hydrocarbons from triglycerides by pyrolysis of vegetable oils and animal fats, the synthesis by co-precipitation and the characterization of several solids by thermo gravimetric analysis, X-rays diffraction, superficial area determined by BET method, chemical composition (ICP-AES), Raman spectroscopy and determination of surface acidity by titration and FTIR. The products obtained in the cracking of soybean oil were analyzed by distillation, acid number, infra-red spectroscopy, density, viscosity, carbon residue, cetane number determination and characterization of the final mixture by CG-MS and CG-FID. The analysis of the products obtained in the presence and in the absence of the oxides synthesized permitted to conclude that all the solids tested presented catalytic activity in the deoxygenation of final products only at the second step of the cracking process.
16
Goujon, Pierre-Andre. "Synthèse par flash combustion et voie solide de formulations céramiques diélectriques dans le diagramme de phase ternaire CaO/ZrO2/TiO2." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMC225.
Full textAbstract:
Le domaine de composition Ca(ZrxTi1-x)O3 a été étudié afin de mieux apprécier ses propriétés diélectriques ; dans le but d'applications pour condensateurs céramiques multicouches à armatures en métaux non nobles. La synthèse de tout ce domaine est mal connue, que ce soit par voie solide, ou par flash combustion. L’étude et l’optimisation (mélangeage/broyage, température de chamottage) de la synthèse par voie solide a permis la synthèse d’échantillons monophasés de la phase pérovskite tout le long du domaine de composition. L’étude de la synthèse par flash combustion a d’abord déterminé que le combustible le plus efficace pour la synthèse était la glycine, puis que l’apport de titane permettant la formation de la phase la plus performante est le nitrate de Titane (TiO(NO3)2) synthétisé à partir du butoxyde de titane.La densification des poudres obtenues par ces deux méthodes a été étudiée et comparée. Ces essais ont permis de comparer plusieurs paramètres sur la densification des échantillons. Ces paramètres sont le mode d’élaboration, le ratio Zr/Ti, ainsi que l’atmosphère de frittage. Des ajouts de frittages seront également testés sur deux compositions : CaZrO3 et Ca(Zr0,8Ti0,2)O3. Ces compositions ont été choisies car elles sont pauvres en titane, ce qui évite la réduction de cet élément qui transformerait le condensateur en semi-conducteur lors d’un frittage sous atmosphère réductrice. Cette étude comparative de ces différents paramètres porte également sur les propriétés diélectriques des échantillons ainsi produitsThe compositional domain Ca(ZrxTi1-x)O3 has been studied in order to understand the formation of solid solution between CaTiO3 and CaZrO3. The aim of this study is the application of such formulations for multilayer ceramic capacitors with non-nobles metal armatures. The synthesis on the line CaTiO3/CaZrO3 is poorly known, either by solid state or by flash-combustion. The study and optimization (mixing/grinding, temperature of calcination) of the solid-state synthesis has allowed the synthesis of single-phase samples made of the perovskite phase along the whole compositional range. The study of the solution-combustion synthesis first determined that the most efficient fuel for the synthesis was glycine, then the fact that the titanium input allowing the formation of the purest phase is TiO(NO3)2, synthesized from titanium butoxide.The densification of the powders obtained by these two methods was studied and compared. These tests allowed to compare several parameters on the densification of the samples. These parameters are the powders’ method of elaboration, the Zr/Ti ratio and the sintering atmosphere. Sintering adds were also be tested on two compositions: CaZrO3 and Ca(Zr0.8Ti0.2)O3. These compositions have been chosen because they are weak in titanium, which avoids reduction and appearance of semi-conduction of Ti that would transform the capacitor into a p-semiconductor during sintering in a reducing atmosphere. This comparative study of these different parameters also deals with the dielectric properties of the samples thus produced
17
Fabre, Jean-Paul. "Élaboration et caractérisation de nouvelles membranes minérales d'ultrafiltration en TiO2 et en ZrO2, réalisées par les techniques "sol-gel"." Montpellier 2, 1987. http://www.theses.fr/1987MON20004.
Full text
18
Salvado, Isabel. "Preparação pelo processo "sol-gel" e caracterização de materiais dos sistemas SiO2-ZrO2, SiO2-TiO2 e SiO2-Al2O3. Aplicação como revestimentos protectores." Doctoral thesis, Universidade de Aveiro, 1990. http://hdl.handle.net/10773/15523.
Full text
19
Schmidt, Jochen [Verfasser], Wolfram [Gutachter] Vogelsberger, Jürgen [Gutachter] Popp, and Eberhard [Gutachter] Müller. "Charakterisierung des Löseverhaltens oxidischer Nanopartikel (TiO2, ZrO2, SiO2) in wässrigen Systemen / Jochen Schmidt ; Gutachter: Wolfram Vogelsberger, Jürgen Popp, Eberhard Müller." Jena : Friedrich-Schiller-Universität Jena, 2009. http://d-nb.info/1178251845/34.
Full text
20
Oliveira, Rodrigo de Matos. "Desenvolvimento de elementos sensores de cerâmicas porosas de ZrO2-TiO2 para aplicação no monitoramento do conteúdo de água em solos." Instituto Nacional de Pesquisas Espaciais, 2010. http://urlib.net/sid.inpe.br/mtc-m19@80/2010/04.27.14.44.
Full textAbstract:
A evolução acelerada na área de automação e de controle de parâmetros ambientais, referentes ao monitoramento de umidade do ar e de solos, tem exigido esforços cada vez maiores no estudo e no aprimoramento de novos materiais para serem aplicados como elementos e sistemas sensores mais confiáveis, versáteis e de menor custo. As propriedades químicas e físicas únicas dos materiais cerâmicos do tipo óxidos metálicos, aliadas à sua capacidade de adsorção superficial de moléculas de água os tornam excelentes candidatos para esta aplicação. Neste trabalho foi proposto utilizar um elemento sensor de cerâmica porosa, que estava sendo estudado como sensor de umidade do ar, para realizar uma investigação de sua aplicação como sensor de umidade para monitoramento do conteúdo de água de solos. Este projeto foi direcionado para o monitoramento do conteúdo de água de solos em áreas com risco de deslizamento de encostas, que tem ocasionado catástrofes em várias regiões do Brasil, principalmente nas últimas duas décadas. Para tanto, neste trabalho, as cerâmicas porosas, confeccionadas a partir de pós comerciais de ZrO$_2$ e de TiO$_2$, foram compactadas por prensagem uniaxial e sinterizadas nas temperaturas de 1000, 1100 e 1200 °C. Foram realizadas as identificações das fases cristalinas presentes pela técnica de difratometria de raios X (DRX), as análises das características morfológicas e das microestruturas dos pós e das cerâmicas sinterizadas pela técnica de microscopia eletrônica de varredura (MEV). Também foram analisados os comportamentos das curvas de distribuição de tamanhos de poros obtidas por porosimetria de mercúrio. As caracterizações elétricas, por medições de capacitância, foram realizadas em função de teores crescentes de umidade em duas amostras de solos, previamente selecionadas e caracterizadas. As análises dos resultados indicaram que os elementos sensores de cerâmica porosa de ZrO$_2$-TiO$_2$, desenvolvidos neste trabalho, são muito promissores quanto ao potencial de utilização no monitoramento do conteúdo de umidade de solo.The hasty evolution in the area of automation and control of environmental parameters concerning to air and soil moisture monitoring has demanded more and more efforts on the study and improvement of new materials to be applied as sensors and sensing systems more reliable, versatile and at lower cost. The sole chemical and physical properties of the metallic oxides type ceramic materials, allied to their capacity of water molecules surface adsorption, make them excellent candidates for this application. The proposal of this work was an investigation of a porous ceramic sensing element, formerly studied as air humidity sensor, to be applied as moisture sensor in soils water content monitoring. The project aimed the soil water content monitoring in hill landslide hazard areas, which has caused catastrophes in several Brazilian cities, mainly in the last two decades. Therefore, in this work, the porous ceramics manufactured from commercial ZrO$_2$ and TiO$_2$ powders, were compacted by uniaxial pressing and sintered at the temperatures 1000, 1100 and 1200 °C. The crystal phases present were identified by x-ray diffractometry (XRD); the analysis of the morphological characteristics and of the microstructures of both the powders and the sintered ceramics were carried out through scanning electron microscopy (SEM). Furthermore, the behavior of the pores sizes distribution curves was obtained by Hg porosimetry. The electric characterization, as function of increasing humidity content of two soil samples, previously selected and characterized, was induced through capacitance measurements. The analyses of the results evidenced that the ZrO$_2$-TiO$_2$porous ceramics sensing elements, developed in this work, are very promising in respect to their potential for utilization as soil moisture content monitoring.
21
Mignotte, Carole Denise. "Environnement local de l'erbium dans des monocristaux de LiNbO3 implantés et des couches sol-gel de TiO2 et ZrO2 dopées." Lyon 1, 1998. http://www.theses.fr/1998LYO10069.
Full textAbstract:
L'optique integree est un domaine en pleine expension, avec en particulier une forte demande pour la realisation d'amplificateur optique fonctionnant a 1. 5m. L'ion erbium est repute pour etre un bon activateur dans cette gamme de longueur d'onde, mais ses proprietes de luminescence dependent fortement de son environnement. L'objectif principal de ce travail est la determination de la structure locale autour d'ions erbium, incorpores, d'une part par implantation ionique dans des monocristaux de niobate de lithium (linbo#3), et d'autre part par dopage dans des couches d'oxyde de titane (tio#2) et de zirconium (zro#2) elaborees par voie sol-gel. La premiere matrice hote (linbo#3) est un materiau non lineaire, commercialement disponible et deja utilise dans des dispositifs optiques, les deux autres, outre l'originalite de leur methode d'elaboration, presentent l'interet d'avoir une faible energie de phonons, limitant ainsi les phenomenes de desexcitation non radiatifs. L'implantation ionique dans les materiaux optiques est encore une technique relativement peu employee. Elle est cependant prometteuse, car elle permet, dans une certaine mesure, de moduler le profil de distribution des ions implantes, via l'energie d'implantation, et egalement d'obtenir des concentrations de dopants superieurs aux limites de solubilite. Des substrats de linbo#3 ont ete implantes a une energie de 300 kev et a une dose de 2. 10#1#6ions/cm#2. Divers recuits thermiques ont ete ensuite effectues. Les modifications structurales et physico-chimiques induites par l'implantation, et leurs evolutions en fonction des parametres de recuit (temperature, duree), ont ete etudiees de facon approfondie a l'aide de la spectroscopie d'absorption x (xas, exafs, xanes), au seuil l#i#i#i de l'erbium. La restauration du reseau et l'evolution de l'environnement de l'erbium ont pu ainsi etre suivis et les sites substitutionnels determines. Ces memes techniques ont ete utilisees pour determiner l'environnement de l'erbium dans les couches sol-gel. Des techniques complementaires de caracterisation ont ete mises en uvre. Des analyses par spectrometrie d'emissions d'ions secondaires (sims) ont permis d'avoir acces aux profils de concentration des ions et a leurs evolutions en fonction des traitements thermiques effectues. Des techniques de diffraction classique aux rayons x ont ete utilisees pour deceler l'apparition eventuelle d'autres phases differentes de linbo#3, dans la couche implantee. Enfin, une breve etude prospective a ete consacree a la caracterisation optique de guides planaires, elabores par implantation d'ions legers, dans des substrats de niobate de lithium et tantalate de lithium dopes terres rares lors du tirage czochralski.
22
Mrabet, Driss. "Synthèse de matériaux nanocomposites par assemblage de nanoparticules métalliques (Au, Cu) et d'oxydes de métaux (TiO2, ZrO2) pour application en catalyse." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25081/25081.pdf.
Full text
23
Olguin, Orozco Enrique. "Catalyseurs sulfures supportés sur des oxydes à base de Al2O3, TiO2 et ZrO2 : cinétique de l'hydrodésulfuration du thiophène et du dibenzothiophène." Lyon 1, 1997. http://www.theses.fr/1997LYO10069.
Full textAbstract:
La necessite d'une plus grande valorisation des fractions lourdes du petrole ainsi qu'une severite accrue de la legislation sur la protection de l'environnement conduisent a la recherche de procedes de raffinage plus performants. Une meilleure connaissance des catalyseurs d'hydrotraitement et de leur mode de fonctionnement justifie les recherches fondamentales aujourd'hui entreprises dans ce domaine, et notre travail de these s'inscrit dans cet objectif. La premiere partie de notre manuscrit rapporte l'utilisation d'oxydes doubles tio#2-al#2o#3 comme supports de catalyseurs mo, como et nimo. Selon la composition du support ti(x)-al, x = tio#2/tio#2+al#2o#3 variant de 0 a 1, on note des differences d'activites importantes, tant dans l'hydrodesulfuration (hds) du thiophene que dans celle du dibenzothiophene (dbt). Diverses caracterisations physico-chimiques (uv, drx, xps, hrem. . . ) ont permis de montrer que selon la composition du support on avait perte d'une partie plus ou moins importante du promoteur (co ou ni) dans une structure alumine amorphe. L'influence de la teneur en h#2s dans le milieu reactionnel a ete approfondie dans la deuxieme partie de notre travail. L'etude cinetique de l'hds du dbt et du thiophene a ete entreprise sur des catalyseurs mo, como et nimo prepares sur al#2o#3, tio#2 et zro#2. Une modelisation des lois cinetiques a ete obtenue en considerant une dissociation heterolytique de h#2 et de h#2s sur la surface de ces sulfures. Selon les conditions de pression, et selon la nature du catalyseur (phase active, support), l'etape cinetiquement determinante apparait etre une hydrogenation (addition d'un ion hydrure) ou une reaction d'elimination de type e#2 (attaque par une base ?s#2#-). Dans ce mecanisme, l'hds des molecules thiopheniques a lieu avec formation prealable d'un intermediaire partiellement hydrogene. L'ensemble de ce travail demontre l'importance du test catalytique (nature de la molecule, condition de pression) sur l'evaluation comparative de nouveaux catalyseurs.
24
Hallil, Abdelmalek. "Simulation de systèmes hétérogènes à base d'oxydes à l'aide de modèles atomiques empiriques à charges variables : application à TiO2 et ZrO2." Paris 11, 2007. http://www.theses.fr/2007PA112307.
Full textAbstract:
L’objectif de ce travail de thèse est l’élaboration de modèles semi-empiriques fiables permettant la simulation à l’échelle atomique de systèmes hétérogènes à base d’oxydes. Nous avons choisi les oxydes TiO2 et ZrO2 comme principaux objets d’étude. Après analyse, nous avons conclu que les modèles classiques ioniques, à charges fixes, basés sur la description de Born et abondamment utilisés dans la littérature, sont inadaptés, principalement du fait qu’ils surestiment largement l’énergie électrostatique. Nous avons donc travaillé à partir de modèles à charges variables basés sur le principe d’égalisation de l’électronégativité des diverses espèces chimiques. Ces modèles permettent aux charges ioniques de s’adapter à leur environnement et de prendre en compte de façon correcte la partie covalente de l’énergie de cohésion. Nous avons amplement amélioré les modèles existants en adaptant les potentiels courte portée de façon à rendre compte le mieux possible de la véritable nature de la liaison chimique dans les oxydes, liée à la structure électronique. En particulier, nous proposons une forme analytique originale, inspirée du modèle quantique du réseau alterné, couplant les deux caractères ionique et covalent de la liaison métal-oxygène. Ce modèle décrit bien les polymorphes de TiO2 (rutile, anatase, brookite) et de ZrO2 (cubique, quadratique, monoclinique). De plus, ce qui est tout à fait nouveau, des résultats très satisfaisants, par comparaison aux résultats expérimentaux ou aux calculs ab initio, ont été obtenus concernant les surfaces, ainsi que les propriétés liées à la lacune d’oxygène en volume et près de la surface (110) du rutileThe aim of our work is to derive reliable semi-empirical models able to simulate heterogeneous oxide-based systems at atomic scale. The TiO2 and ZrO2 systems have been chosen as working examples. In a first step, energetic analysis showed that pure ionic models with fixed charges that are widely encountered in the literature are irrelevant to describe oxides, as they largely overestimate the electrostatic energy. We have then used variable-charge models that are derived from the electronegativity equalization principle. These models allow the ionic charges to dynamically adapt themselves to their structural or chemical environment, and also to evaluate the covalent part of the cohesive energy correctly. We strongly improved the existing models by modifying short-range potentials in order to describe the real nature of chemical bonding in oxides that is related to their electronic structure, as well as possible. In particular, taking advantage of the quantum alternating-lattice model, we derived an analytical expression that links the covalent and the ionic characters of the metal-oxygen bond. This model describes the three polymorphs of TiO2 (rutile, anatase, brookite) and ZrO2 (cubic, quadratic, monoclinic) correctly. Moreover, we obtained new results both for TiO2 surfaces and oxygen vacancy in bulk and near the (110) surface of rutile, that are in a very satisfactory agreement with experimental results and ab initio calculations
25
Pereira, Cristiane Alves Sierra. "Catalisadores de CuO, Fe2O3 ou Co3O4 suportados em TiO2, CeO2 ou ZrO2: preparação via Sol-gel in situ ou impregnação e avaliação na redução de NO com CO." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/3911.
Full textAbstract:
Made available in DSpace on 2016-06-02T19:55:32Z (GMT). No. of bitstreams: 1
4381.pdf: 2748711 bytes, checksum: 4ba9831d0665b24b6f48f775d30927d2 (MD5)
Previous issue date: 2012-04-13Universidade Federal de Minas Gerais
The minimization of the emissions of nitrogen oxides (NOx) is a subject of crucial interest, since them cause serious environmental problems which affect human health, vegetation and fauna. With the purpose to abate NOx, processes involving their catalytic reduction show strong potential. In the case of the reduction of NO with CO a meaningful advantage arises, once both pollutants are removed simultaneously. In order to obtain efficient and stable catalysts for this reaction, many studies have been done with the aim to improve the catalytic activity by achieving a better favorable metal-support interaction to the occurrence of the reaction and a better distribution of the active phases on the support. In this context, the objective of this study was to prepare Cu, Fe and Co based catalysts supported on TiO2, CeO2 and ZrO2 to be applied in the abatement of NO with CO. The addition of the precursors of the active phases was made during the synthesis of the support via the sol-gel method (in situ addition). Furthermore, catalysts with the same composition were prepared by conventional methods. Results from the N2 adsorption/desorption measurements show that the sol-gel method was efficient to prepare supports with improved textural properties. H2-TPR and UVVIS-DRS data evidenced the presence of Cu, Fe or Co oxides in the respective catalysts, which mostly did not show characteristic X-ray diffraction peaks of those oxide phases, suggesting their high dispersion on the supports. In general, results of the reduction of NO to N2 with CO revealed that the catalysts prepared via sol-gel are as active as those prepared by conventional routes, which demonstrate the great potential of the catalysts preparation via the sol-gel in situ procedure, which diminishes the number of the synthesis steps saving time and energy. In general, among the studied supports, ceria presented a more favorable metal-support interaction. In the presence of O2, SO2 and water steam, catalysts 6,5Cu/CeP, 5,5CuZrSG and 8,4Fe/TiC showed no significant changes in their activity and selectivity, indicating that they present high stability to be used under the severe conditions of real processes.
A minimização das emissões de óxidos de nitrogênio (NOx) é assunto de interesse crucial, pois geram graves problemas ambientais que afetam à saúde humana, à flora e à fauna. Para abater os NOx, processos envolvendo à sua redução catalítica apresentam forte potencial. No caso da redução catalítica de NO com CO, tem-se a vantagem adicional de minimizar as emissões de ambos poluentes. Para a obtenção de catalisadores eficientes e estáveis para essa reação, muitos estudos têm sido desenvolvidos no sentido de aumentar a atividade por meio de uma interação metalsuporte mais favorável ao processo reativo e de se conseguir uma melhor distribuição da fase ativa no suporte. Nesse contexto, o objetivo do presente estudo foi preparar catalisadores para a redução de NO com CO à base de óxido de Cu, Fe ou Co, suportados em TiO2, CeO2 ou ZrO2, com a adição do precursor da fase ativa durante a preparação do suporte via processo sol-gel (adição in situ). Além disso, catalisadores de mesma composição foram preparados por rotas convencionais. Resultados de medidas de adsorção/dessorção de N2 dos suportes mostram que o método sol-gel utilizado é mais eficiente no preparo de suportes com propriedades texturais melhoradas. Análises de RTP-H2 e ERD-UVVIS evidenciaram a presença dos óxidos de Cu, Fe ou Co em todos os catalisadores, os quais, em sua maioria, não apresentaram picos de difração de raios X característicos dessas fases, o que sugeriu sua alta dispersão no suporte. Em geral, os resultados da redução de NO a N2 com CO mostraram que os catalisadores preparados pelo método sol-gel in situ são tão ativos quanto os catalisadores preparados por métodos convencionais, o que demonstra o forte potencial desse procedimento, que resulta no uso de um número menor de etapas na preparação do catalisador, com a consequente economia de tempo e energia. De maneira geral, dentre os suportes estudados a céria mostrou uma relação metal-suporte mais favorável ao processo de óxidoredução. Os catalisadores 6,5Cu/CeP, 5,5Cu-ZrSG e 8,4Fe/TiC, na presença de O2, SO2 e vapor de água não apresentaram alteração significativa da sua atividade e seletividade, mostrando uma alta estabilidade para atuar sob as drásticas condições dos processos reais.
26
Backović, Marija [Verfasser]. "Thermodynamic optimization of the PbO-ZrO2-TiO2 (PZT) system and its application to the processing of composites of PZT ceramics and copper / vorgelegt von Marija Čančarević." Stuttgart : Max-Planck-Inst. für Metallforschung, 2007. http://d-nb.info/995377243/34.
Full text
27
Percio, Maycon Fernando. "Desenvolvimento de suportes vítreos e vitrocerâmicos baseados no sistema Li2O-BaO-SiO2 mofificados pelos óxidos Nb2O5, TiO2, V2O5 e ZrO2, para microextração em fase sólida (SPME-CG)." Universidade Estadual do Oeste do Paraná, 2012. http://tede.unioeste.br:8080/tede/handle/tede/1911.
Full textAbstract:
Made available in DSpace on 2017-07-10T18:08:21Z (GMT). No. of bitstreams: 1
Maycon Fernando Percio.pdf: 4386871 bytes, checksum: fd68bea53c4d4cbfe32a314a01715c6e (MD5)
Previous issue date: 2012-02-28Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In the present work a vitreous composition based on combination of the oxides BaO-SiO2-Li2O modified by adding of oxides Nb2O5, TiO2, V2O5 and ZrO2 as nucleating agent was evaluated and used in the manufacture of glass and glass-ceramic fibers for use in SPME-CG. The stability of the resulting glasses was accompained by X-ray diffraction (XRD) and differential thermal analysis (DTA). The stability parameters of Weinberg (KW), Hubrÿ (KH), Lu e Liu (KLL), Du and Huang (KDU) and Saad and Poulain (KSP) were obtained by DTA data. By KSP was observed that stability of glassy phases follows the descending order: Composition 5 (ZrO2) > Composition 2 (Nb2O5) > Composition 1 (without nucleant) > Composition 4 (V2O5) > Composition 3 (TiO2). Through these data it was possible to determine the apparent activation energies of the crystallization process by the crystallization peaks of the DTA curves, whereby the decreasing order was obtained: Composition 5 (ZrO2)> Composition 4 (V2O5) > Composition 2 (Nb2O5) > Composition 3 (TiO2) > Composition 1 (without nucleant). It was found, through the Avrami index, a surface crystallization mechanism of the compositions that leads to a correspondent transition to the glass ceramic. From DRX data obtained after thermal treatment at varying time, the TTT diagrams (Time, Temperature and Transformation) of the compositions were constructed, which delimited the conditions for preparation of glass ceramic fibers. The XRD analysis indicated that the main crystalline phases formed after heat treatments are rhombic Li2SiO3 Li2Si2O5. The fibers obtained were further tested in chromatographic analysis by HS-SPME-GC of the methanol in aqueous solution at concentrations of 10 and 100 mgL-1 with satisfactory results.
No presente trabalho, foram estudadas composições vítreas baseada na combinação dos óxidos Li2O-BaO-SiO2 modificadas pelos óxidos Nb2O5, TiO2, V2O5 e ZrO2, utilizados como nucleantes na fabricação de fibras de vidro e vitrocerâmicas para a utilização em SPME-CG. Determinou-se a estabilidade vítrea para cada composição através da difração de raio-X (DRX) e análise térmica diferencial (DTA) sendo observada a estabilidade das fases vítreas na ordem decrescente: Composição 5 (ZrO2) > Composição 2 (Nb2O5) > Composição 1 (sem nucleante) > Composição 4 (V2O5) > Composição 3 (TiO2). Através destes dados foi possível determinar as energias de ativação aparente das fases cristalinas através dos picos de cristalização das curvas de DTA, cuja ordem decrescente obtida foi: Composição 5 (ZrO2) > Composição 4 (V2O5) > Composição 2 (Nb2O5) > Composição 3 (TiO2) > Composição 1 (sem nucleante). Verificou-se através do índice de Avrami que as composições vítreas obtidas apresentaram mecanismo de nucleação de superfície para a formação do vitrocerâmico. Os dados de DTA possibilitaram a obtenção de diagramas de Tempo, Temperatura e Transformação (TTT), que delimitaram as condições de preparo das fibras vitrocerâmicas. Foram fabricados 5 tipos diferentes de fibras vítreas (Fibras A), que após tratamento térmico deram origem a fibras vitrocêramicas parcialmente cristalizadas (Fibras B) e fibras vitrocerâmicas totalmente cristalizadas (Fibras C), resultando um total de 15 espécies de fibras de composições e estruturas cristalinas diferentes. As análises por DRX indicaram que as principais fases cristalinas formadas depois dos tratamentos térmicos são Li2SiO3 e Li2Si2O5 ortorrômbicos. As fibras obtidas foram ainda testadas em análises cromatográficas por Cromatografia Gasosa na extração de metanol em solução aquosa nas concentrações de 10 e 100 mgL-1 com resultados satisfatórios.
28
Leroy, Céline Marie. "Films mésoporeux de TiO2 ou ZrO2 dopés EuIII : de la localisation des ions EuIII à l'étude des corrélations entre les propriétés de luminescence et la réactivité de surface." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2009. http://tel.archives-ouvertes.fr/tel-00604673.
Full textAbstract:
La recherche scientifique contemporaine en matière de matériaux est largement orientée autour de l'optimisation et l'élaboration de nouveaux matériaux poly-fontionnels, multi-structurés et aux dimensions réduites. De tels matériaux conduisent à s'intéresser à la problématique des comportements spécifiques résultant des différentes interfaces mises en jeu ; il peut s'agir d'interfaces physiques entre différents milieux (états différents, compositions chimiques différentes ...) ou des interfaces entre différentes propriétés. Dans ce contexte, nous nous sommes intéressés aux corrélations pouvant exister entre les propriétés de luminescence et la réactivité de surface de films mésoporeux d'oxyde métalliques dopés avec des ions EuIII. Ces deux propriétés étant fortement dépendantes de la structure des matériaux, une grande partie de notre travail a été dédiée à la caractérisation de cette dernière. Un intérêt particulier a été porté à l'étude des conséquences de la présence des ions EuIII et à la localisation de ces derniers au sein des matrices étudiées. Finalement, il est apparu que la luminescence des ions EuIII au sein des films mésoporeux à base de TiO2 peut permettre de suivre les réactions redox se produisant au sein des pores, comme par exemple la photo-dégradation de composés organiques ou la photo-réduction de sels métalliques. La photo-réduction in situ permet la formation de réseaux périodiques de nanoparticules métalliques. Ces matériaux offrent donc de nombreuses perspectives d'applications dans des domaines aussi variés que les télécommunications optiques, la photonique, la photocatalyse...
29
Leroy, Céline Marie. "Films mésoporeux de TiO2 ou ZrO2 dopés EuIII : de la localisation des ions EuIII à l’étude des corrélations entre les propriétés de luminescence et la réactivité de surface." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13906/document.
Full textAbstract:
La recherche scientifique contemporaine en matière de matériaux est largement orientée autour de l’optimisation et l’élaboration de nouveaux matériaux poly-fontionnels, multi-structurés et aux dimensions réduites. De tels matériaux conduisent à s’intéresser à la problématique des comportements spécifiques résultant des différentes interfaces mises en jeu ; il peut s’agir d’interfaces physiques entre différents milieux (états différents, compositions chimiques différentes …) ou des interfaces entre différentes propriétés. Dans ce contexte, nous nous sommes intéressés aux corrélations pouvant exister entre les propriétés de luminescence et la réactivité de surface de films mésoporeux d’oxyde métalliques dopés avec des ions EuIII. Ces deux propriétés étant fortement dépendantes de la structure des matériaux, une grande partie de notre travail a été dédiée à la caractérisation de cette dernière. Un intérêt particulier a été porté à l’étude des conséquences de la présence des ions EuIII et à la localisation de ces derniers au sein des matrices étudiées. Finalement, il est apparu que la luminescence des ions EuIII au sein des films mésoporeux à base de TiO2 peut permettre de suivre les réactions redox se produisant au sein des pores, comme par exemple la photo-dégradation de composés organiques ou la photo-réduction de sels métalliques. La photo-réduction in situ permet la formation de réseaux périodiques de nanoparticules métalliques. Ces matériaux offrent donc de nombreuses perspectives d’applications dans des domaines aussi variés que les télécommunications optiques, la photonique, la photocatalyse…Materials contemporary scientific research is largely devoted to the optimization and the elaboration of new poly-functional, multi-structured and size-reduced materials. Then, specific behaviors due to the different interfacial aspects of those materials – physical interfaces between different matter states, different chemical phases… or properties interfaces – have become a major issue requiring further investigations. In this context, our work deals with correlations that could be established between luminescence properties and surface reactivity of EuIII-doped metal oxide mesoporous thin films. As properties can be linked to materials structure, an important part of our work has been dedicated to structural characterization. EuIII ions incorporation specific effects and ions location within film walls have been particularly studied. Finally, it appeared that EuIII ions luminescence could provide a mean to follow redox reactions occurring within pores, such as organic compounds photo-degradation or metallic salts photo-reduction. In situ photo-reduction can lead to periodic arrays of metallic nanoparticles. La photo-réduction in situ permet la formation de réseaux périodiques de nanoparticules métalliques. Those materials can open up the way in many applications such as optical telecommunication, photonics, photocatalysis…
30
Pruvost-Bonnaillie, Claire. "Etude de la combustion catalytique de particules carbonées sur des systèmes oxydes : CeO2, ZrO2, TiO2 et Al2O3, promus ou non par des ajouts d'ions Cu2+ et/ou K+." Littoral, 2001. http://www.theses.fr/2001DUNK0077.
Full textAbstract:
Les objectifs de ce travail sont de tester la réactivité et la sélectivité en CO2 de catalyseurs oxydes promus par des ajouts d'ions Cu2+ et/ou K+ mais aussi d'étudier le mécanisme d'oxydation des particules carbonées. Un dispositif alliant les analyses thermiques (gravimétriques et différentielles) et la chromatographie a permis de mesurer la réactivité et la sélectivité en CO2 des catalyseurs. Pour les oxydes purs, la réactivité et la sélectivité en CO2 respecte l'ordre CeO2>ZrO2>TiO2>Al2O3. Des conditions de contact important accroissent les interactions entre le carbone et l'oxyde, favorisant l'oxydation du carbone. Néanmoins, la présence d'oxygène gazeux au niveau de la surface d'échange entre le carbone et le catalyseur est essentiel pour amorcer la réaction de combustion. Lors de l'étude des oxydes promus par des ajouts d'ions Cu2+, il a été montré que les ions cuivriques assurent un effet promoteur de contact entre le carbone et le catalyseur et permettent également d'améliorer la sélectivité en CO2. Une augmentation importante de la réactivité du solide à base de TiO2 suite à l'ajout d'ions Cu2+ a pu être corrélée à la présence de CuO au sein du catalyseur Cu/TiO2. L'action catalytique des espèces cuivriques répond aux caractéristiques d'un mécanisme rédox. Outre l'effet promoteur de contact et de sélectivité, la présence d'ions K+ sur les oxydes CeO2, Al2O3, TiO2 et ZrO2 permet essentiellement d'augmenter la vitesse d'oxydation du carbone. Enfin, un ajout conjoint des ions Cu2+ et K+ a été réalisé sur les oxydes TiO2 et ZrO2. Une amélioration notable de réactivité est obtenue sur K-Cu/ZrO2 en condition de faible contact et sur K-Cu/TiO2 en condition de fort contact. Cette observation a été reliée à la présence de CuO à la surface de K-Cu/TiO2, permettant un mécanisme rédox alors que sur K-Cu/ZrO2, les Cu2+ sont bien dispersés et ne participent pas à la réactivité. Les propriétés du potassium concernant sa capacité à augmenter la vitesse de combustion du noir de carbone sont conservées pour les deux oxydes ternaires.
31
Brito, Juliana Ferreira de. "Sistemas fotoeletrocatalíticos baseados em eletrodos de Ti/TiO2-CuO, NtTiO2-NsCuO, NtTiO2-ZrO2 e GDL-Cu2O aplicados de forma isolada e concomitantemente à oxidação da água, redução de CO2 dissolvido e oxidação de compostos orgânicos da água residual de petróleo." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/154923.
Full textAbstract:
Submitted by JULIANA FERREIRA DE BRITO (jfbrito@ymail.com) on 2018-08-21T19:45:38Z
No. of bitstreams: 1
Tese Versão Final com Aprovação Sec.pdf: 4876214 bytes, checksum: a1729d16365422160af084f862835a94 (MD5)Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2018-08-23T17:57:49Z (GMT) No. of bitstreams: 1 brito_jf_dr_araiq_int.pdf: 4876214 bytes, checksum: a1729d16365422160af084f862835a94 (MD5)
Made available in DSpace on 2018-08-23T17:57:49Z (GMT). No. of bitstreams: 1 brito_jf_dr_araiq_int.pdf: 4876214 bytes, checksum: a1729d16365422160af084f862835a94 (MD5) Previous issue date: 2018-08-10
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O presente trabalho investigou materiais semicondutores aplicados em sistema fotocatalítico, eletrocatalítico e fotoeletrocatalítico com vistas a produzir a redução de CO2, oxidação da água, oxidação de compostos orgânicos da água residual de petróleo e redução de CO2 concomitante a oxidação de compostos orgânicos. Na primeira parte deste trabalho foi avaliado o desempenho dos eletrodos de heterojunção de dióxido de titânio e óxido de cobre II, na forma não nanoestruturada, Ti/TiO2-CuO, e em uma configuração de nanoestruturas, NtTiO2-NsCuO, para promover a redução fotoeletrocatalítica de CO2 com vistas a formação dos álcoois metanol e etanol. Empregando o eletrodo de Ti/TiO2-CuO em baixas temperaturas foi possível obter uma reação com 91% de seletividade a metanol, atingindo 0,30 mmol L-1 de formação após 2 h de reação. Em temperatura ambiente foi possível atingir a geração de 0,10 mmol L-1, mesmo valor obtido para o eletrodo completamente nanoestruturado de NtTiO2-NsCuO. Estudos com trapeadores de lacunas fotogeradas (eficientes oxidantes) mostraram que no sistema nanoestruturado competem com a concomitante oxidação de metanol, sendo necessário a separação destas lacunas no sistema. Na segunda parte deste trabalho estudou-se o reator híbrido fotoeletroquímico/eletroquímico empregando eletrodos de difusão de gás decorados com óxido de cobre I (GDL-Cu2O) e nanotubos de TiO2 decorados com óxido de cobre II (NtTiO2-CuO) para a redução eletroquímica de CO2 e a oxidação da água, respectivamente. O arranjo deste reator permitiu realizar ambas as reações simultaneamente em compartimentos separados por membrana trocadora de prótons, obtendo 0,027 mmol L-1 de formiato, 0,020 mmol L-1 de acetato e 0,050 µmol min-1 de hidrogênio após 24 h de reação. 98% de eficiência faradáica foi obtido para sistema irradiado com luz UV-Vis, mostrando ser possível promover a oxidação de compostos orgânicos concomitante à redução de CO2. Na terceira parte do trabalho investigou-se a eficiência de eletrodos de nanotubos de TiO2 em sistemas fotocatalíticos, ozonização, fotoeletrocatálise e ozonização acoplada a fotoeletrocatálise quando aplicados na oxidação da água residual de petróleo. A comparação entre as técnicas mostrou que com a ozonização fotoeletrocatalítica atingiu-se 97,6% de redução de cor, 99,9% na redução da turbidez, 99,2% de remoção de carbono inorgânico, 73,5% de redução da DQO, 35,3% de redução na concentração de cloreto e 96% na redução da concentração de fluoreto após 2h de reação. Os compostos remanescentes no processo foram: benzaldeído, álcool benzílico, octa-decano e ácido hexadecanóico detectados por CG-MS. Na quarta etapa deste trabalho estudou-se o sistema fotoeletrocatalítico composto por fotoânodo de NtTiO2-ZrO2 e o cátodo GDL-Cu2O para promover a oxidação de álcool benzílico no compartimento anódico, escolhido como composto modelo, visto que foi este um dos compostos mais resistente à oxidação fotoeletrocatalítica da água de petróleo, concomitante à redução de CO2 no compartimento catódico. Após 3 h de reação a oxidação do álcool benzílico atingiu 68%, concomitante a geração simultânea de 3,75 mmol L-1 de metanol e 0,96 mmol L-1 de etanol. Estes resultados são pioneiros e trazem uma nova perspectiva para os estudos de oxidação de poluentes concomitante a redução de CO2 em sistemas de amostras complexas por fotocatálise ou fotoeletrocatálise.
The present work investigated semiconductor materials applied in photocatalytic, electrocatalytic and photoelectrocatalytic system with the target to produces CO 2 reduction, water oxidation , oxidation of organic compounds present s in petroleum wastewater and CO 2 reduction concomitant to a n oxidation of organic compounds. In the first part of this work was evaluated the performance of the heterojunction electrodes t itanium dioxide and copper oxide II, in the non - nanostructured form, Ti/TiO 2 - CuO and, in the nanostructured configuration, NtTiO 2 - NsCuO, to promote the photoelectrocatalytic reduction of CO 2 intending methanol and ethanol formation. Employing the Ti/ TiO 2 - CuO in low temperature was possible to obtain 91% of selectivity to methanol , reaching 0 . 30 mmol L - 1 after 2h of reaction. Under room temperature was possible to reach the formation of 0 . 10 mol L - 1 , the same value obtained for the completely nanostructure d NtTiO 2 - CuO. The study with trapper s of the holes photogenerated (efficien t oxidants ) show that the nanostructured system compete s with the concomitant oxidation of the methanol formed, been necessary to separate the holes in this system. In the second part of this work was studied the hybrid reacto ph otoele ctrochemistry/electrochemistry employing electrodes of gas diffusion layer decorated with copper oxide I (GDL - Cu 2 O) and TiO 2 nanotubes decorated with copper oxi de II (NtTiO 2 - CuO) for electrochemistry reduction of CO 2 and water oxidation, respectively. The arrangement of this reactor allowed to perform both reactions simultaneously in compartments separated by protons exchange membrane , obtain 0 . 027 mmol L - 1 of formate , 0 . 020 mmol L - 1 of acetat e and 0 . 050 μmol min - 1 of hydrogen after 24 h of reaction. 98% of faradaic efficiency was obtained for the system irradiated with UV - Vis light, showing be possible to promote the oxidation of organic compounds concomitant t o CO 2 reduction. In third part of the work investigated the efficiency of TiO 2 nanotubes electrodes in systems of photocatalysis , ozonation, photoelectrocatalysis and ozonation coupled to photoelectrocatalysis , when applied in the oxidation of petroleum wastewater. The comparison between the technics showed that the photoelectrocatalytic ozonation reached reduction of 97.6% in color , 99 . 9% in turbid ity , 99 . 2% in in organic carbon , 73 . 5% in C O D , 35 . 3% in the conc entra tion of chlo ride and 96 .0 % in the concentra tion of fluor ide after 2h of reaction . The rema ining compounds in the process were benzaldehyde, benzyl al cohol, octadecane and hexadecane acid detected by GC - MS. In the fourth 18 stage of this work was studied the photoelectrocatalytic system compound by photoanodes of NtTiO 2 - ZrO 2 and the cathode GDL - Cu 2 O to promote the oxidation of benzyl alcohol in the anodic compartment, showed as model molecule , once it was one of the compounds more resistant to the photoelectrocatalytic oxidation of the petroleum wastewater , concomitant to the CO 2 reduction in the cathodic compartment. After 3h of reaction the oxidation of benzyl alcohol reach 68.0% concomitant to the simultane ous generation of 3.75 mmol L - 1 of metha nol and 0.96 mmol L - 1 of ethanol. These results are pioneers and bring a new perspective to the study of oxidation of pollutants concomitant to the reduction of CO 2 in systems with complex samples by photocatalysis or photoelectrocatalysis.
2013/25343-8
32
Yung, Matthew Maurice. "Oxidation catalysis in environmental applications nitric oxide and carbon monoxide oxidation for the reduction of combustion emissions and purification of hydrogen streams /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1187128442.
Full text
33
Vast, Nathalie. "Etude ab initio des propriétés physiques des matériaux." Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00440923.
Full textAbstract:
Mon activité de recherche fondamentale dans le groupe de théorie du Laboratoire des Solides Irradiés concerne l'étude des propriétés des matériaux d'intérêt pour le CEA, dans les domaines du nucléaire ou de la nanoélectronique. Elle a pour objectif d'atteindre une description théorique -sans paramètre ajustable- des processus contrôlant l'excitation électronique, ainsi que la relaxation -ou désexcitation- électronique, et couvre: - Les propriétés de la matière hors excitation - l'état fondamental; - Les propriétés de l'état excité, abordées sous l'angle de la spectroscopie pour les électrons de valence; - Les vibrations collectives des atomes, leur couplage avec les électrons, et leurs effets sur le transport électronique ou la relaxation électronique. Ces études requièrent un environnement de calcul intensif et l'accès aux ordinateurs du Grand Equipement National de Calcul Intensif GENCI. Dans ce manuscrit, est d'abord rappelé comment calculer la fonction diélectrique inverse en théorie de la fonctionnelle de la densité dépendante du temps, et quel est le lien avec la fonction de perte électronique observée. Des résultats théoriques sur la fonction diélectrique inverse dans des oxydes non corrélés représentés par le dioxyde de titane TiO$_2$ et la zircone ZrO$_2$ sont décrits. Ensuite sont donnés les principaux résultats théoriques pour les calculs de spectres d'absorption optique pour l'oxyde de cuivre Cu$_2$O et la zircone ZrO$_2$. J'y présente une nouvelle interprétation de travail sur le noyau permettant de modéliser les effets excitoniques en théorie de la fonctionnelle de la densité dépendante du temps. Enfin, les derniers calculs menés sur les carbures de bore sont rappelés.
34
Wei, Chen Chih, and 陳志維. "The hydrogenation of 1-methylnaphthalene over Pt/TiO2-ZrO2 d Pd/TiO2-ZrO2." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/57807637152606122928.
Full text
35
Kratschmer, Tim. "Flammgespritzte Schichten im System Al2O3-TiO2-ZrO2." Doctoral thesis, 2010. https://tubaf.qucosa.de/id/qucosa%3A22745.
Full textAbstract:
Beim Flammspritzen von Mischungen im System Al2O3-TiO2-ZrO2 treten vielfältige Effekte auf. Es kommt z.B. zur Ausbildung eines amorphen Anteils, der in Form von amorphen Sublamellen, dem primären amorphen Anteil, und in dendritisch geprägten Bereichen, dem sekundären amorphen Anteil im Gefüge vorliegt. Dieser beeinflusst die mechanischen Eigenschaften deutlich. Bei einer Temperaturbehandlung entstehende Ausscheidungen von ZrO2 oder verschiedenen Zirkoniumtitanaten beeinflussen die mechanischen Eigenschaften ebenfalls signifikant.
36
Lo, Cho-Ching, and 羅卓卿. "Photoreduction of Carbon Dioxide via TiO2 and ZrO2 Photocatalysts." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/2jn9d3.
Full textAbstract:
博士國立中山大學
環境工程研究所
96
This study investigated the photocatalytic reduction of CO2 in a self-designed closed circulated batch reactor system and a bench-scale batch photocatalytic reactor. The photocatalysts tested included titanium dioxide (TiO2, Degussa P-25) and zirconium oxide (ZrO2). The reductants investigated included hydrogen (H2), water vapor (H2O), and hydrogen plus water vapor (H2+H2O). The wavelengths of incident near ultra-violet (UV) and UV lights for the photocatalysis of TiO2 and ZrO2 were 365 nm and 254 nm, respectively. The initial concentrations of CO2 ranged from 0.2-5.0% and the reaction temperature ranged from 35-95 ○C. The incident near-UV (or UV) light with wavelength of 365 nm (or 254 nm) was irradiated by a 15-watt low-pressure mercury lamp. The photocatalytic reaction was conducted continuously for approximately two hours. Reactants and products were analyzed by a gas chromatography with a flame ionization detector followed by a methanizer (GC/FID-methanizer). Experimental results indicated that glass pellets coated with TiO2 had better photoreduction efficiency than ZrO2. The highest yield rates of the photoreduction of CO2 were obtained using TiO2 with H2+H2O and ZrO2 with H2. Photoreduction of CO2 over TiO2 with H2+H2O formed CH4, C2H6, and CO in the yield of 32.95~94.60, 0.80~18.55, 1.12~21.78 μmol/g, respectively, while the photoreduction of CO2 over ZrO2 with H2 formed CO in the yield of 0.34~4.99 μmol/g. Results obtained from the operating parameter tests showed that the photoreduction rate increased with the initial concentration of carbon dioxide and resulted in more product accumulation. The photoreduction rate of carbon dioxide increased with reaction temperature, which promoted the formation of products. Concurred with previous researches, the reaction rate of major products over TiO2 and ZrO2 were higher than previous investigations of CO2 photoreduction. Furthermore, the spectra of FTIR showed that formic acid (HCOOHads), methanol (CH3OHads), carbonate (CO32−ads), bicarbonate (HCO32−ads), formate (HCOO−ads), formic acid (HCOOH ads), formaldehyde (HCOHads) and methyl formate (HCOOCH3 ads) formed on the surface of TiO2 and ZrO2 photocatalysts. The detected reaction products supported the proposal of two reaction pathways for the photoreduction of CO2 over TiO2 and ZrO2 with H2 and H2O, respectively. A modified bimolecular Langmuir-Hinshelwood kinetic model was developed to simulate the reaction temperature, CO2 initial concentration and relative humidity promotion and inhibition of the photoreduction of CO2. Additionally, the modified L-H kinetic model was successfully applied to simulate the photoreduction rate of CO2. The result showed that CO2 could be reduced by used solar light over TiO2 and ZrO2 photocatalysts. The reaction products of CO2 photoreduction over TiO2 were CH4, C2H6, and CO in the yield of 2.16~2.995, 0.057~0.128, 0.078~0.134 μmol/g, respectively, while the photoreduction of CO2 over ZrO2 formed only CO in the yield of 0.023~0.051 μmol/g. Furthermore, experimental results indicated that TiO2 gave the highest average photo energy efficiency (AEf) of ~4.13%, and apparent quantum efficiency (φA) of ~1.05%. However, the ZrO2 gave the highest average photo energy efficiency (AEf) of 5.07×10-3%, and apparent quantum efficiency (φA) of ~1.54×10-2%.
37
Lee, Ya-Ling, and 李雅玲. "Sulfur Tolerance on Hdrogenation of Tetralin over Pt/TiO2-ZrO2." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/25886145077480389381.
Full textAbstract:
碩士國立清華大學
化學工程學系
98
Hydrogenation of tetralin over Pt/Al2O3 and Pt/TiO2-ZrO2 were executed in a bench scale fixed bed reactor under 160-270 °C and 450 psi in the presence or absence of sulfur compounds in feed. The activity was compared by the rate constant of hydrogenation of tetralin, which was considered to follow a first-order kinetic model. In the range of sulfur content from 0 ppm to 30 ppm, the rate constant (kS) inversely proportion to the sulfur content (CS) was observed. Thus, a method to obtain sulfur adsorption equilibrium (KS) was developed by Langmuir-Hinshelwood model. The sulfur adsorption equilibrium constant of Pt/TiO2-ZrO2 and Pt/Al2O3 were 7×106 and 2×107, respectively. Moreover, the heat of adsorption of sulfur could be obtained from the apparent activity energy in the presence and absence of sulfur. The heat of adsorption of Pt/TiO2-ZrO2 and Pt/Al2O3 were -19.4 and -41.0 kJ/gmol, respectively. The results showed that the sulfur desorbed easier while platinum supported on TiO2-ZrO2. Meanwhile, less than 1 ppm sulfur was detected in the product of hydrotreating a 15 ppm S feedstock over Pt/TiO2-ZrO2. These results suggest that Pt/TiO2-ZrO2 exhibits not only a high sulfur tolerance hydrogenation catalyst but also possesses the desulfurization ability.
38
Kratschmer, Tim [Verfasser]. "Flammgespritzte Schichten im System Al2O3-TiO2-ZrO2 / vorgelegt von Tim Kratschmer." 2010. http://d-nb.info/1012206351/34.
Full text
39
LIU, DE-SHAN, and 劉得山. "The dehydrogenation of ethylbenzene over mixed metal oxides TiO2 -Fe2 O3 -ZrO2." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/20656481996736505907.
Full text
40
Lin, Shih-Yao, and 林詩堯. "Study of ZrO2-TiO2 Dielectric Thin Film by the Sol-gel Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/25595700470588726982.
Full textAbstract:
碩士國立聯合大學
電機工程學系碩士班
96
The ZrO2-TiO2 (ZrTiO4) thin films were deposited on ITO/Glass substrates by using sol-gel technology. The effects of various thermal treatments on the physical properties and electric properties of ZrO2-TiO2 thin film also have been studied with various heat-treated temperatures, heat-treated times, and annealed temperatures. Besides, the ZrO2-TiO2 thin film were investigated by resistance switch effect and expected to applied in resistive random-access memory (RRAM). The ZrTiO4 thin film in this study were polycrystalline when annealed temperature of 700oC for 1hr. When the annealed temperature increased, the grain size more large, and the grain size of non-heated treated thin film were large than heated treated thin films. The surface roughness of thin film was reduced by heated treated temperature and annealed temperature obtained from AFM images. The leakage current mechanism of thin film in high annealed temperature was observed as Schottky Emission, and there were always be Pool-Frenkel mechanism in low annealed temperature. The optimum conditions for the leakage current of ZrTiO4 thin film in this study were heat-treated temperature of 450oC for 30 min and annealed temperature of 800oC for 1hr. It could be arrived 1.04×10-6 (A/cm2) when the electric field on 10 (kV/cm). In the RRAM characteristic, all of the thin films have slightly resistance switching effect in annealed 600oC and 700oC for 1hr. The best of the resistance switching in this study were non-heated treated temperature and annealed temperature 600oC for 1 hr could be arrived 102. The result show that ZrTiO4 thin film were a candidate for applied in RRAM.
41
Σκαρμούτσος, Διονύσιος Σ. "Χαρακτηρισμός και έλεγχος ιδιοτήτων των μικτών οξειδίων στο σύστημα ZrO2-Y2O3-TiO2 (Cr2O3) καθώς και των κεραμομεταλλικών Ni/ZrO2-Y2O3-TiO2, ως υλικών ανόδου κελίου καυσίμου στέρεου ηλεκτρολύτη (SOFC)." 2003. http://nemertes.lis.upatras.gr/jspui/handle/10889/237.
Full textAbstract:
Στα πλαίσια της αναζήτησης νέων µεθόδων παραγωγής ενέργειας υψηλής απόδοσης και φιλικής προς το περιβάλλον, ένα µεγάλο µέρος των ερευνητικών δραστηριοτήτων σε διεθνή κλίµακα έχει στραφεί στην ανάπτυξη της τεχνολογίας των κελίων καυσίµου στερεού ηλεκτρολύτη, SOFC’s (Solid Oxide Fuel Cell’s). Λόγω της φιλικότητάς τους προς το περιβάλλον τα SOFC’s µπορεί να εισαχθούν για χρήση και σε αστικές περιοχές, όπου παράλληλα µε την παραγόµενη ηλεκτρική ενέργεια, είναι δυνατόν να αξιοποιηθεί και η εκλυόµενη θερµική ενέργεια για θέρµανση χώρων, αυξάνοντας συνολικά την αποτελεσµατικότητά τους. Ένα από τα µειονεκτήµατα που εµφανίζονται κατά την µακρόχρονη λειτουργία ενός «State of the art» κελίου καυσίµου αποτελούµενο από Ni/YSZ-κεραµοµεταλλικό (άνοδος) – YSZ (ηλεκτρολύτη) – LaMnO3 περοβσκίτης (κάθοδος) – LaCrO3 περοβσκίτης (συνδέτης) είναι η υποβάθµιση της απόδοσής του, η οποία µεταξύ άλλων οφείλεται και στην αστάθεια της µικροδοµής του κεραµοµεταλλικού ηλεκτροδίου της ανόδου, λόγω συσσωµάτωσης της µεταλλικής φάσης. Στόχος της εργασίας ήταν η βελτίωση της ευστάθειας της µικροδοµής, καθώς και η διερεύνηση της δυνατότητας ελάττωσης του ποσοστού συµµετοχής της µεταλλικής φάσης στο κεραµοµεταλλικό υλικό του ηλεκτροδίου της ανόδου, χωρίς σηµαντική απώλεια σε ηλεκτρική αγωγιµότητα. Για τον σκοπό αυτό παρασκευάσθηκαν, χαρακτηρίσθηκαν και ελέγχθηκαν οι ιδιότητες µικτών κεραµικών οξειδίων επιλεγµένων συνθέσεων του τριµερούς συστήµατος ZrO2-Y2O3-TiO2 (η Cr2O3) καθώς και τα αντίστοιχα κεραµοµεταλλικά Ni/ZrO2-Y2O3-TiO2 µε προσθήκη 30,40 και 45 vol% Ni. Aπό τα αποτελέσµατα προέκυψε ότι σε θερµοκρασία πύρωσης 1400ºC σχηµατίζονται µικτά οξείδια µε την κυβική δοµή του πλέγµατος φθορίτη και συντελεστή θερµικής διαστολής αντίστοιχο του ηλεκτρολύτη (YSZ). Η ηλεκτρική τους αγωγιµότητα σε ατµόσφαιρα Ar+4%H2 είναι µικτού τύπου (ιοντική + ηλεκτρονιακή), όµως λόγω της χαµηλής απόλυτης τιµής στην θερµοκρασιακή περιοχή λειτουργίας του κελίου καυσίµου (900-1000ºC) δεν προσφέρονται για χρήση αυτούσια, ως κεραµικές άνοδοι. ΠΕΡΙΛΗΨΗ-ABSTRACT 6 Από πειράµατα διαβροχής στο σύστηµα Ni σε επαφή µε τα µικτά οξείδια προέκυψε ότι η παρουσία TiO2 βελτιώνει την συνάφεια και ως εκ τούτου την ισχύ του δεσµού στην διεπιφάνεια µετάλλου/κεραµικού. Η βελτίωση των διεπιφανειακών ιδιοτήτων έχει σαν αποτέλεσµα των ελάττωση του συντελεστού διαστολής των κεραµεταλλικών και την καλλίτερη µηχανική προσαρµογή τους στον ηλεκτρολύτη (YSZ).Επίσης, λόγω της µείωσης του ρυθµού συσσωµάτωσης των σωµατιδίων της µεταλλικής φάσης, οι τιµές της ηλεκτρικής αγωγιµότητας των κεραµοµεταλλικών παραµένουν σε υψηλά επίπεδα και µετά από µακροχρόνια παραµονή σε συνθήκες λειτουργίας (1000ºC, 1000h). Πρώτες ηλεκτροχηµικές µετρήσεις σε κελία καυσίµου µε κεραµοµεταλλική άνοδο, αποτελούµενη από επιλεγµένη σύνθεση µικτού οξείδίου του τριµερούς συστήµατος ως κεραµικής συνιστώσας, έδωσαν ενθαρρυντικά αποτελέσµατα αφήνοντας σηµαντικά περιθώρια για επίτευξη ικανοποιητικών επιδόσεων, µε βελτίωση του τρόπου κατασκευής.Within the research framework for the development of alternative, friendly to the environment methods for the production of energy, significant effort is focusing on the SOFC’s (Solid Oxide Fuel Cell’s) technology. Due to their low pollutant emissions fuel cells can be applied inside civil areas were the electrical power can be used together with the thermal energy generated by the cell, increasing the total performance of the device. The “state of the art” fuel cell structure is the anode electrode (Ni/YSZ cermet), the electrolyte (YSZ), the cathode electrode (LaMnO3 perowskite) and the interconnector (LaCrO3 perowskite). One of the disadvantages of fuel cells is the performance degradation due to the instability of the YSZ/Ni anode electrode microstructure caused by metal phase sintering. This work aims to the improvement of microstructure stability as well as the possibility of reducing the amount of the metallic phase to the anode cermet without affecting its electrical properties. New ceramic materials of the ternary system ZrO2-Y2O3-TiO2 (or Cr2O3) were produced and characterized as well as their corresponding cermets Ni/ZrO2-Y2O3-TiO2 by the addition of 30,40 and 45 vol% Ni. After calcination at 1400ºC mixed oxides are formed having cubic fluorite crystal structure and similar thermal expansion properties to the YSZ ceramic oxide. The electrical conductivity in reducing atmosphere Ar+4%H2 is of electronic and ionic type but due to the low values in the working temperature range of a fuel cell (900-1000ºC) they cannot be used independently as anode materials. Wetting experiments of the system Ni in contact to those mixed oxides showed that TiO2 presence enhances the adherence and the bond strength at the metal ceramic interface. Improvement of the interfacial properties results to the decrease of cermets thermal expansion improving in this way the mechanical adjustment of the anode to the electrolyte. Also due to the decrease of the sintering tendency of the metallic phase particles, the electrical conductivity values remain at high values after long term annealing at high temperature (1000ºC, 1000h). Early electrochemical tests performed to fuel cells having a selected anode material showed encouraging results leaving space for improvement especially to the construction methods used in order to achieve satisfactory performance.
42
Lin, Kuan-Ting, and 林冠廷. "Microstructural Evolution and Interfacial Reactions between Ti Melt and ZrO2/ CaO/ TiO2 Composites." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/57w85u.
Full text
43
Luo, Jhan-Ting, and 羅展廷. "Effects of TiO2 and ZrO2 on the Characteristics of Calcium Aluminate Glass-Ceramics." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/37854300065610329225.
Full textAbstract:
碩士大同大學
材料工程學系(所)
94
Calcium aluminate glasses have good optical transmittance in the middle-infrared (3-5 μm region) and good mechanical properties. In order to apply the glasses in a severer environment, the IR properties must be improved. In this study, the glass was converted into glass-ceramics to enhance the mechanical properties at ambient and high temperature, CaO, Al2O3, MgO, and BaO were chosen as the main components of the glass. TiO2 and ZrO2 were added as the nucleating agents stimulate internal nucleation in the glass-ceramics. According to the experimental results, the viscosity of the glass with addition of 8.26 wt% of TiO2 (T8) was slightly decreased and the glass can be internally nucleated. The glass-ceramic which was nucleated at the optimum nucleating temperature (755℃) for 8 h, followed by crystallizing at 850℃ for 4 h was full of Ca3Al2O6 phase. The above-mentioned T8 glass-ceramic showed only 25 % decrease in IR transmittance, 17 % increase in hardness, 61℃ increase in dilatometric softening point, and 19 % increase in Young’s modulus.
44
房靜玲. "Acid-base bifunctional characters of TiO2-ZrO2 catalysts for the catalytic reforming reactions." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/93627006596453964273.
Full text
45
LEE, CHENG-HSUN, and 李承訓. "Characterization of Dye-Sensitized Solar Cells with ZrO2- and TiO2-Codoped ZnO Film Electrodes." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/b69n4g.
Full textAbstract:
碩士明新科技大學
電子工程系碩士在職專班
107
The dye-sensitized solar cells with undoped and ZrO2-/TiO2-codoped ZnO working electrodes have been successfully fabricated and assembled into the photo-electro-chemical devices, and furthermore investigated the effect of various codoping amount of ZrO2 and TiO2 in ZnO thin-film working electrodes on optoelectronic characterization of the dye-sensitized solar cells. The experiment result shows that the dye-sensitized solar cells with various co-doped weight percentage ratio of ZrO2 and TiO2 in the ZnO thin-film electrodes are prepared by a series of procedures, the maximum short-circuit current density, Jsc, of the solar cells with the co-doped weight ratio of 6.0 wt% mesured by solar simulator is shown to be 3.20 mA / cm2, and the corrsponding value of the short-circuit current (Isc) is 0.73 mA. When the smaples without co-dopant metal oxides in the ZnO thin-film working electrodes, the maximum open-circuit voltage (Voc) value is meaured to be 649 mV, the photoelectric conversion efficiency is 0.92% for the sample with the co-dopant weight ratio of 2.0 wt%, and it is confrimed that the incident photon-to-electron conversion efficiency is apparently improved. When the sample with co-dopant weight ratio of 10.0 wt% of ZrO2 and TiO2, there is no remarkable improvement in the photoelectric conversion efficiency of the sample and its value shows 0.61%. This effect can be attributed to the excessive doping proportion of metal oxide, it resulted in the formation of lattice defects and the occurrence of the annihilation of photo-excited carriers by capture during carriers transportation in the working electrode, and then lead to the photoelectric energy conversion efficiency is relatively reduced.
46
Istiqomah, Nurul Alvia, and 艾諾如. "The Role of Metal Ion Impregnation on TiO2-ZrO2 Binary Oxide in Ammonia Adsorption." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/c8f2h8.
Full textAbstract:
碩士國立交通大學
環境工程系所
107
Four types of transition metal ions, including copper (Cu), nickel (Ni), tungsten (W), and zinc (Zn), were selected to be impregnated on the porous TiO2-ZrO2 (TZ) binary oxide with an impregnation method and the roles of those transition metals in the surface acidity and ammonia adsorption of the oxides were systematically examined and clarified. The TZ and the impregnated powders (TZM, where M means the impregnated ions) maintained the porous structure and high surface areas (174-188 m2/g) up to 600oC. While all the impregnated ions incrased the Lewis acidity of the TZ substrate, the Cu and Zn species additionally increased the Bronsted acidity as the result of structural mismatch between the tetrahedral Cu and Zn species and the octahedral Ti and Zr species. The W and Ni spcecies, which had high coordination numbers, consumed surface OH groups, thus introducing Lewis acidity primarily. The ammonia adsorption capacity was in the order of TZCu> TZZn> TZNi> TZW> TZ powders. The additional OH groups on the Cu and Zn ions were the major contributor to the high ammonia adsorption of the TZCu and TZZn adsorbents. The TZCu powder showed the highest ammonia adsorption capacity of 1.81 mmol/g at the surface Cu/(Ti+Zr) atomic ratio of 6 10-3. Over this critical Cu concentration, cross condensation between the Cu-OH groups decreased the active sites for the adsorption. The adsorption capacity of the TZCu powder decreased by 26.8% after high-temperatured desorption as the consequence of elimination of OH groups from the Cu ions. However, the loses of adsorption sites were able to be recovered by exposinig the used adsorbent in the ambient air. The high ammonia adsorption capacity, a wide range of acidity strength, and good structural stability enable the impregnated TZ powder to be a promising adsorbent for ammonia removal in variety of industries.
47
Shen, Po-Fan, and 沈柏汎. "Effects of tungstate and phosphate species on the acidity of ZrO2-TiO2 solid acids." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/50639041136011908784.
Full textAbstract:
碩士國立交通大學
環境工程系所
103
Owing to the low electronegtivity of Zr4+ and Ti4+ ions, a porous ZrO2-TiO2 composite was prepared using a templating method and was further modified with tungstate and phosphate species, which contain high electrongativity centers, through incorporation or impregnation method to increase the surface aidity. The substrate exhibited a high surface area of 195 m2/g with a pore size of 6.3 nm. The quantity of the acidic sites was 859 µmol/g. Because of the great solubility of the ZrO2 in the TiO2 matrix, crystallization is inhibited and the porous structure is stabilized till 600C. Rather than impregnation, incorporation of the two modifiers enhanced the surface acidity to a higher degree. The incorporated phosphate and tungstate species increased the number of the acidic sites to 1,547 and 972 µmole/g, respectively. The optimal P/M and W/M raito which leads to the highest acidity was 0.44 and 0.16, respectively. The W6+ ions with a high coordination number and electronegativity within the surface lattice resulted in oxygen vacancies and strong Lewis acid sites. On the other hand, P5+ ions led to Bronsted acidity because their low coordination number creates substaintial anounts of hydroxyl groups on the Ti4+ or Zr4+ centers. Compared to the WO3 moieties, PO43- species is more capable of stabilizing the microstructure of the substrate to aginast thermally induced transformation. Therefore, the incorporated phospahe speices increased the surface area to 270 m2/g and maintained the small pore size of 3.5 nm. The repeated NH3-TPD test indicated that the modified solid acid peformed high recoverability. In addition, its acid amount and density was higher than those of the commercial zeolite, suggesting the phosphated ZrO2-TiO2 solid acids a promising adsorbent for removal of base gases.
48
Chen, Po-Chen, and 陳柏臻. "Influence and Durability of ZrO2 and TiO2 Coating on Type 304 and 304L Stainless Steels." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/67542759585416480816.
Full text
49
Tsai, Meng-Hsiu, and 蔡孟修. "Laser ablation condensation of TiO2 and ZrO2: implications for the densification and coalescence of nanoparticles." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/43748323349735246282.
Full textAbstract:
博士國立中山大學
材料科學研究所
93
This thesis is about the phase transformation, shape, size distribution and coalescence of TiO2 (part I) and ZrO2 (part II) nanopartilces produced by Nd-YAG laser ablation on metal targets under oxygen background gas, and characterized by analytical electron microscopy. The optimum laser ablation condition that satisfactory and routinely yield high-pressure phases of TiO2 (i.e. α-PbO2-type and fluorite-related structures) and ZrO2 with high residual stress were reported. Part I-1 focuses on physical coagulation, by Van der Waals force, of the TiO2 condensates at temperatures up to about 1000 K as a result of post-condensation radiant heating. In part I-2, imperfect oriented attachment of nanoparticles over specific surfaces is rationalized to cause accretion and defects for the rutile condensates. Brownian motion may proceed above a critical temperature for anchorage release at the interface of imperfect attached nanoparticles until an epitaxial relationship is reached. Part I-3 deals with further the Brownian-type rotation of the imperfectly impinged α-PbO2-type TiO2 and rutile nanocondensates until interfacial-energy cusp was reached. In part I-4 laser ablation condensation synthesis of dense TiO2 polymorphs and their phase transformations were documented. Part II-1 is about dense tetragonal (t)-ZrO2 and cubic (c-) nanocondensates which were synthesized under very rapid heating and cooling by pulsed Nd-YAG laser ablation with oxygen background gas. The t-ZrO2 nanoparticles were found to form deformation twins/faults and followed unique transformation path upon local electron dosage. Electron diffraction indicated that the dense c- and t- phase with specific size and residual stress were allowed to relax and/or kinetically phase change into lower-energy state as constrained by the intersections of the internal energy vs. cell volume plots calculated for the two polymorphs (Part II-2).
50
CHEN, JHIH-FONG, and 陳志峰. "Preparation of ZrO2/TiO2 Composite Photocatalyst and their Studies on the Decomposition of Organic Matter." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/f38n2j.
Full textAbstract:
碩士國立雲林科技大學
化學工程與材料工程系
106
Water contaminated with organic dyes is a serious environmental problem. The study focuses on modified photocatalyst for the purpose of degrading dye wastewater. Photocatalyst cannot effectively utilize sunlight to remove pollutants since sunlight has less than 5% of ultraviolet light energy. Therefore, it is desired to improve photocatalyst's shortcomings, photodegradation efficiency as well as the degradation of organic pollutants. In this study, zirconium dioxide and graphene oxide were successfully added to P25 commercial photocatalyst. The photocatalytic properties were analyzed through XRD, DLS, FT-IR, Raman, SEM, and EDS. Through the analysis of UV-Vis, it showed that the redshift happened in absorbing wavelengths and the energy gap was gradually reduced after zirconium dioxide and graphene oxide with the composite material we prepared were added. Finally, the photocatalyst of each component went through visible-light degradation test. The photodegradation rate of the composite photocatalyst, with the addition of 192 mg of zirconium dioxide and 2% of graphene oxide by electrospraying was 49.92%. The result has few difference compared to that with the addition of 192 mg of zirconium dioxide only. The main reason is that the agglomeration causes low photodegradation rate. Furthermore, a cycle test was conducted to demonstrate that our composite photocatalyst can be reused.