Made available in DSpace on 2014-12-17T15:42:21Z (GMT). No. of bitstreams: 1 JoseEMS_TESE.pdf: 5374821 bytes, checksum: 56fe60cd3bbf0a42f7512c62fe5b976e (MD5) Previous issue date: 2013-03-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Were synthesized spinel-type ferrites with general formula Ni0,8Mg0.2-xMxFe2O4, where M represents the doping Mn, Co or Mn + Co simultaneously, x ranges for the values 0.02, 0.05 and 0.1. The value of x was divided by 2 in cases where M equals Mn and Co conjugates. We used the citrate precursor method and heat treatment to obtain the phases at 1100?C. The materials were characterized by XRD, TGA/ DTGA, SEM, MAV and reflectivity measurements by the method of waveguide. Powders to 350?C/3.5 h were crystalline and nanosized. According to the results this temperature all powders have a percentage of ferrite phase over 90%. The composition had the addition of Mn and Co simultaneously showed a higher percentage of secondary phase NiO, 5.8%. The TGA/DTGA curves indicate that this sample reached phase (s) crystalline (s) at lowest temperatures. The X-ray diffractograms of the samples calcined at 350?C and 1100?C were treated with the Rietveld refinament technique. The powders calcined at 1100 ?C/3h in air show to be 100% except spinel phase composition with 0.02 doping. The micrographs show clusters of particles with sizes smaller than 1 μm in calcination temperature of 1100?C which agreed with the result of Rietveld refinement. In the compositions doped with Mn were higher values of magnetization (45.90 and 53.20 Am2/kg), which did not cause high microwave absorption. The theoretical calculation of magnetization (MT) was consistent with the results, considering that there was agreement between the increase of magnetization experimental and theoretical. It was observed that there was the interrelation of the final effect of absorption with the thickness of MARE, the composition of ferrimagnetic materials and in particular the specific values of frequency. The analysis shows that the reflectivity increases in the concentration of cobalt increased the frequency range and also for absorption 10.17 GHz and 84%, respectively. The best result of chemical homogeneity and the value of 2.96 x 10-2 tesla coercive field were crucial for high performance ferrite absorber with 0.1 cobalt. The Cobalt has high magnetocrystalline anisotropy, it is associated with an increased coercive field, Hc. Therefore, this property improves the results of reflectivity of spinel ferrites / Foram sintetizadas ferritas do tipo espin?lio com f?rmula geral Ni0,8Mg0,2-xMxFe2O4, onde M representa os dopantes Mn, Co ou Mn + Co simultaneamente, x varia para os valores 0,02; 0,05 e 0,1. O valor de x foi dividido por 2 nos casos em que M equivale a Mn com Co conjugados. Foi utilizado o m?todo dos citratos precursores e tratamento t?rmico na obten??o das fases a 1100?C. Os materiais foram caracterizados por DRX, TGA/DTGA, MEV, MAV e medidas de refletividade pelo m?todo de guia de ondas. Os p?s a 350?C/3,5h foram cristalinos e nanom?tricos. De acordo com os resultados nesta temperatura todos os p?s apresentam um percentual de fase ferrita superior a 90%. A composi??o que teve a adi??o de Mn e Co simultaneamente apresentou maior percentual de fase secund?ria NiO, 5,8%. As curvas TGA/DTGA indicam que essa amostra alcan?ou fase(s) cristalina(s) em temperaturas mais baixas. Os difratogramas de raios X das amostras calcinadas a 350?C e 1100?C foram tratados pela t?cnica de refinamento Rietveld. Os p?s calcinados a 1100?C/3h em atmosfera ambiente mostram ser 100% de fase espin?lio exceto a composi??o com 0,02 de dopantes. As micrografias apresentam aglomerados de part?culas com tamanhos menores que 1 μm na temperatura de calcina??o de 1100?C, o que concordou com o resultado de refinamento Rietveld. Nas composi??es dopadas com Mn ocorreram os maiores valores de magnetiza??o (45,90 e 53,20 Am2/kg), o que n?o acarretou alta absor??o de microondas. O c?lculo te?rico da magnetiza??o (MT) foi coerente com os resultados, considerando-se que houve concord?ncia entre o aumento das magnetiza??es experimental e te?rica. Observa-se que houve interrela??o do efeito final de absor??o com a espessura do MARE, a composi??o do material ferrimagn?tico em particular e os valores espec?ficos de freq??ncia. A an?lise de refletividade indica que o aumento na concentra??o de cobalto aumentou a faixa de freq??ncia e a absor??o para 10,17 GHz e 84%, respectivamente. O resultado indica que a melhor homogeneidade qu?mica e o valor 2,96 x 10-2 tesla de campo coercitivo foram determinantes para o alto desempenho absorvedor da ferrita com 0,1 de cobalto. O Cobalto tem alta anisotropia magnetocristalina, isto est? associado ao aumento do campo coercitivo, Hc. Portanto, essa propriedade melhora os resultados de refletividade das ferritas espin?lio

Solid oxide fuel cells (SOFCs) have gained renewed interest due to their high energy-conversion efficiency, new discovery of fossil fuel sources, and low greenhouse gas emission. However, performance degradation during long-term operation is one of the greatest challenges to overcome for commercialization of SOFCs. At intermediate temperatures, chromium (Cr) vapor species that form over chromia-forming alloy interconnect, can transport and deposit in the cathode, and poison the cathode performance. Although extensive studies have been conducted on the Cr-poisoning phenomena, the mechanism of cathode performance degradation still needs to be clarified. Therefore, there is an urgent need to understand the degradation mechanisms and develop corresponding mitigation strategies. In this research, anode-supported cells with (La,Sr)MnO3-based cathode were fabricated. The cells were electrochemically tested with and without the presence of chromia-forming alloy interconnect, and operating conditions including cathode atmosphere, current condition, and interconnect contact were varied independently. It was found that both humidity and cathodic current promote chromium poisoning. Microstructural characterizations also confirmed that larger amounts of chromium-containing deposits are present at the cathode/electrolyte interfaces of the cell tested with cathodic current and/or humidity. With the help of free energy minimization calculations, the equilibrium cell potentials for Cr vapor species reductions are estimated and found to be very close to the open-circuit potential of the cell. Combining the experimental and computational results, the roles of humidity and cathodic current in Cr-poisoning are evaluated, and a mechanism associated to Cr vapor species dissociation at the triple-phase-boundaries is proposed. To evaluate the Cr-poisoning effects on cell performance, an analytical polarization model is used for quantitatively separating the contribution of various cell polarizations. By curve-fitting the current-voltage traces to this model, the changes of cathode polarizations due to Cr-poisoning are quantified. Under normal operating conditions, the cathodic activation polarization is determined to be most negatively impacted by Cr-poisoning. Mitigation of the Cr-poisoning effects using a dense lab-developed CuMn1.8O4 spinel interconnect coating was demonstrated. Employing the spinel coated interconnect mesh in on-cell tests, it was found that both the degradation in cell performance and Cr deposition in the cathode are significantly mitigated.

This thesis concerns catalytic combustion for gas turbineapplication using a low heating-value (LHV) gas, derived fromgasified waste. The main research in catalytic combustionfocuses on methane as fuel, but an increasing interest isdirected towards catalytic combustion of LHV fuels. This thesisshows that it is possible to catalytically combust a LHV gasand to oxidize fuel-bound nitrogen (NH3) directly into N2without forming NOX. The first part of the thesis gives abackground to the system. It defines waste, shortly describesgasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns thedevelopment and testing of potential catalysts for catalyticcombustion of LHV gases. The objective of this work was toinvestigate the possibility to use a stable metal oxide insteadof noble metals as ignition catalyst and at the same timereduce the formation of NOX. In paper II pilot-scale tests werecarried out to prove the potential of catalytic combustionusing real gasified waste and to compare with the resultsobtained in laboratory scale using a synthetic gas simulatinggasified waste. In paper III, selective catalytic oxidation fordecreasing the NOX formation from fuel-bound nitrogen wasexamined using two different approaches: fuel-lean andfuel-rich conditions. Finally, the last part of the thesis deals with deactivationof catalysts. The various deactivation processes which mayaffect high-temperature catalytic combustion are reviewed inpaper IV. In paper V the poisoning effect of low amounts ofsulfur was studied; various metal oxides as well as supportedpalladium and platinum catalysts were used as catalysts forcombustion of a synthetic gas. In conclusion, with the results obtained in this thesis itwould be possible to compose a working catalytic system for gasturbine application using a LHV gas. <b>Keywords:</b>Catalytic combustion; Gasified waste; LHVfuel; RDF; Biomass; Selective catalytic oxidation; NH3; NOX;Palladium; Platinum; Hexaaluminate; Garnet; Spinel;Deactivation; Sulfur; Poisoning

The present thesis was to study non-metallic inclusions during vacuum degassing in ladle treatment. Emphasize was mostly given to liquid CaO-Al2O3 inclusions. A series of industrial experiments were carried out at Uddeholm Tooling AB, Hagfors, Sweden. To gain an insight into the industrial findings, laboratory investigations were also performed. Large number of steel samples were collected and examined. Liquid calcium aluminate inclusions with low SiO2 and high SiO2 were often found with spinel inclusions before vacuum degassing. Laboratory experiments showed that spinel would react with the dissolved Ca in the liquid steel forming calcium aluminate inclusions. This laboratory results agreed with the industrial observation that spinel phase was quite often found in the center of the calcium aluminate phase. After vacuum degassing, most of the inclusions were calcium aluminate liquid inclusions. When dissolved Al level was low, 2 types of liquid calcium aluminate inclusions with considerably different SiO2 contents were found to coexist even at the end of the process. In view of the lack of the thermodynamic data for SiO2 activities in the low silica region, thermodynamic measurements were conducted in the CaO-Al2O3-SiO2-MgO system. The experimental results could reasonably explain the coexistence of the two types of the liquid oxide inclusions. While the total number of inclusions decreased during vacuum degassing, the number of bigger inclusions (&gt;11.3 μm) increased generally in used ladles. This finding was in accordance with the previous studies, wherein, ladle glaze was found to be responsible for the supply of bigger inclusions. The behaviors of several types of inclusions in liquid steel were examined using a laser scanning confocal microscope (LSCM). While alumina inclusions tended to impact on each other, agglomerate and grow very quickly, none of the other types of inclusions, such as spinel and calcium aluminate was observed to agglomerate. The results of LSCM study agreed well with the industrial observation. Examination on a huge number of inclusions did not show any indication of impact and physical growth of the inclusions, except the alumina inclusions. The removal of inclusions around open-eye in a gas-stirred ladle was experimentally studied by a cold model with oil and water. Most of the simulated inclusions were brought up to the oil phase by gas-water plume. Inclusion removal into oil layer took place when the inclusions passed through the sphere-bed of the oil layer around the open-eye. A calculation showed that the contribution of metal-gas plume in inclusion removal was much larger than that of buoyancy mechanism. The results of the industrial experiments revealed that the inclusions distribution strongly depended on stirring condition. When a ladle was stirred by both gas and induction, inclusion removal near slag layer was significant. / QC 20100803

In this presentation it is demonstrated that the unique magnetic properties of superparamagnetic cobalt-spinel ferrite nanoparticles can be employed in several novel applications. A method to selectively capture and remove pathogens from infected organisms to improve longevity is presented. Evidence is provided to show that automated methods using modified forms of hemofiltration or peritoneal dialysis could be used to eliminate the particle/pathogen or particle/infected cell conjugates from the organism postoperatively. It is shown that disparately functionalized nanoparticles can be used in concert as drug carrier and release mechanisms. Lastly, we provide preliminary evidence to support the use of magnetic nanoparticles for controlling reaction kinetics.

<p>This thesis concerns catalytic combustion for gas turbineapplication using a low heating-value (LHV) gas, derived fromgasified waste. The main research in catalytic combustionfocuses on methane as fuel, but an increasing interest isdirected towards catalytic combustion of LHV fuels. This thesisshows that it is possible to catalytically combust a LHV gasand to oxidize fuel-bound nitrogen (NH3) directly into N2without forming NOX. The first part of the thesis gives abackground to the system. It defines waste, shortly describesgasification and more thoroughly catalytic combustion.</p><p>The second part of the present thesis, paper I, concerns thedevelopment and testing of potential catalysts for catalyticcombustion of LHV gases. The objective of this work was toinvestigate the possibility to use a stable metal oxide insteadof noble metals as ignition catalyst and at the same timereduce the formation of NOX. In paper II pilot-scale tests werecarried out to prove the potential of catalytic combustionusing real gasified waste and to compare with the resultsobtained in laboratory scale using a synthetic gas simulatinggasified waste. In paper III, selective catalytic oxidation fordecreasing the NOX formation from fuel-bound nitrogen wasexamined using two different approaches: fuel-lean andfuel-rich conditions.</p><p>Finally, the last part of the thesis deals with deactivationof catalysts. The various deactivation processes which mayaffect high-temperature catalytic combustion are reviewed inpaper IV. In paper V the poisoning effect of low amounts ofsulfur was studied; various metal oxides as well as supportedpalladium and platinum catalysts were used as catalysts forcombustion of a synthetic gas.</p><p>In conclusion, with the results obtained in this thesis itwould be possible to compose a working catalytic system for gasturbine application using a LHV gas.</p><p><b>Keywords:</b>Catalytic combustion; Gasified waste; LHVfuel; RDF; Biomass; Selective catalytic oxidation; NH3; NOX;Palladium; Platinum; Hexaaluminate; Garnet; Spinel;Deactivation; Sulfur; Poisoning</p>

Σκοπός της παρούσας διδακτορικής διατριβής ήταν η ανάπτυξη ενός αποτελεσματικού καταλυτικού συστήματος με βάση το χαλκό, για την αναμόρφωση της μεθανόλης. Για το σκοπό αυτό εξετάστηκαν οι καταλυτικές ιδιότητες τριών συστημάτων βασιζόμενων σε καταλύτες χαλκού και παρασκευασμένων με τη μη συμβατική μέθοδο της καύσης: CuO-CeO2, τροποποιημένων καταλυτών CuO-CeO2 και Cu-Mn-O για την προαναφερθείσα διεργασία, καθώς και τα βέλτιστα δείγματα των καταλυτών CuO-CeO2 και Cu-Mn-O υποστηριγμένων σε μεταλλικούς αφρούς Al. Τα φυσικοχημικά χαρακτηριστικά των καταλυτών CuO-CeO2, βρέθηκαν να εξαρτώνται από τις παραμέτρους σύνθεσης. Ο βέλτιστος καταλύτης παρασκευάστηκε με λόγο Cu/(Cu+Ce)= 0.15. Στους τροποποιημένους καταλύτες CuO-CeO2, ένα μέρος του τροποποιητή εισχωρεί στο πλέγμα της δημήτριας, οδηγώντας στο σχηματισμό στερεού διαλύματος. Αυτό είχε ως αποτέλεσμα να επηρεαστούν τα φυσικοχημικά χαρακτηριστικά των δειγμάτων, αλλά και η καταλυτική συμπεριφορά τους. Οι σπινελικοί καταλύτες Cu-Mn-O είναι πολύ ενεργοί παρά τη μικρή ειδική επιφάνειά τους. Η ενεργότητά τους είναι συγκρίσιμη με αυτή των εμπορικών καταλυτών Cu-Zn-Al. Ο βέλτιστος καταλύτης ήταν αυτός με λόγο Cu/(Cu+Mn)= 0.30. Εξίσου αποδοτικοί για την παραγωγή υδρογόνου μέσω αναμόρφωσης της μεθανόλης, μονολιθικοί καταλύτες Cu-Ce/Al foam και Cu-Mn/Al foam παρασκευάστηκαν με τη μέθοδο της καύσης. Με βάση τα ευρήματα της ισοτοπικής μελέτης, προτείνεται για τον καταλύτη Cu-Mn-O ότι η αναμόρφωση πραγματοποιείται αποκλειστικά μέσω μηχανισμού που περιλαμβάνει τον ενδιάμεσο σχηματισμό μυρμηκικού μεθυλεστέρα. Για τους καταλύτες Cu-Ce-O και Cu-Zn-Al πραγματοποιείται ταυτόχρονα και μηχανισμός που περιλαμβάνει ως ενδιάμεσο είδος το διοξομεθυλένιο. / The scope of the present thesis was the development of an effective catalytic copper-based system for methanol reforming. The catalytic properties of three different copper-based systems prepared via the non conventional combustion method, were investigated for the aforementioned process: CuO-CeO2, modified CuO-CeO2 and Cu-Mn-O, as well as the optimal CuO-CeO2 and Cu-Mn-O oxide cata¬lysts supported on Al metal foam. The physicochemical characteristics of CuO-CeO2 catalysts were found to be influenced by the parameters of the synthesis. The optimal catalyst was prepared with Cu/(Cu+Ce) ratio equal to 0.15. In the case of modified CuO-CeO2 catalysts, at least part of dopant cations gets incorporated into the CeO2 lattice leading to solid solution formation. As a result, the physicochemical characteris¬tics of the samples were influenced, as well as their catalytic performance. Cu-Mn spinel oxide catalysts were found to be highly active despite their low surface area. Their activity is comparable to that of commercial Cu-Zn-Al catalysts. The optimal catalyst was prepared with a Cu/(Cu+Mn) ratio equal to 0.30. Structured Cu-Ce/Al foam and Cu-Mn/Al foam catalysts prepared via in situ combustion method were equally effective for hydrogen production via methanol reforming. Based on the findings of an isotopic study, a mechanism has been proposed for the reforming reaction over Cu-Mn-O, where methyl formate is formed as a reaction intermediate. An additional reaction mechanism is taking place over Cu-Ce-O and commercial Cu/ZnO/Al2O3 catalysts, resulting in the intermediate dioxomethylene.

Im Rahmen dieser Arbeit wurde der Einfluss von Defekten auf die Eigenschaften von Ferrit-Dünnfilmen untersucht. Die Dünnfilme wurden mit Hilfe von gepulster Laserabscheidung bei verschiedenen Züchtungsparametern hergestellt. Durch Variation der Substrattemperatur und des Sauerstoffpartialdrucks wurden Dünnfilme verschiedener kristalliner Qualität gezüchtet. Diese wurden hinsichtlich ihrer chemischen Komposition mit Hilfe von energie-dispersiver Röntgenspektroskopie und Röntgenphotoelektronenspektroskopie untersucht. Durch Korrelation der Ergebnisse mit Messungen zum zirkularen magnetischen Röntgendichroismus, konnte eine partielle Inversion der Spinellstruktur nachgewiesen werden. Der Grad der Inversion ist höher für geringe Abscheidetemperaturen. Für diese defektreichen Dünnfilme zeigen Röntgenbeugungsuntersuchungen eine geringere kristalline Ordnung der Dünnfilme. Die strukturellen Defekte haben einen maßgeblichen Einfluss auf die elektrischen und magnetischen Eigenschaften der Ferrit-Dünnfilme. So zeigen die Ferrit-Dünnfilme für geringe Züchtungstemperaturen eine erhöhte elektrische Leitfähigkeit, während Dünnfilme, die bei hohen Substrattemperaturen gezüchtet wurden, isolierend sind. Die Temperaturabhängigkeit der elektrischen Leitfähigkeit kann auf thermisch aktivierte Hopping-Leitung oder die Leitung zwischen Clustern, die in einer Matrix eingebettet sind, zurückgeführt werden. Die magnetischen Eigenschaften von Zinkferrit-Dünnfilmen werden maßgeblich durch Defekte in der Spinellstruktur bestimmt, da es nominell in der normalen Spinellstruktur kristallisiert und daher antiferromagnetisch ist. Die partielle Inversion der Eisen- und Zinkionen führt zu Ferrimagnetismus in den Zinkferrit-Dünnfilmen, der mit Hilfe von SQUID-Messungen in dieser Arbeit eingehend untersucht wurde. Durch Korrelation der Ergebnisse der verschiedenen Untersuchungsmethoden konnten Rückschlüsse auf die dominierenden Defekte in den Ferrit-Dünnfilmen geschlossen werden. So sind zum einen Defekte auf atomarer Skala, wie Antisite-Defekte und divalenten Fe-Ionen für die erhöhte elektrische Leitfähigkeit und die größere Magnetisierung der defektreichen Dünnfilme verantwortlich. Zum anderen können ausgedehnte Defekte, im Speziellen Cluster, die in einer amorphen Matrix eingebettet sind, nicht ausgeschlossen werden.

Made available in DSpace on 2014-12-17T14:06:59Z (GMT). No. of bitstreams: 1 LucianoLMS.pdf: 2498297 bytes, checksum: 4e0c9395aebdb6d0be7a37737a51ca92 (MD5) Previous issue date: 2008-04-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Oxide type spinel AB2O4 presents structure adjusted for application in the automobile industry. The spinel of cobalt has many practical applications had its excellent physical and chemical properties such as catalyst in hydrocarbon oxidation reaction. The CeO2 has been used in many of these processes because it assigns to a material with excellent thermal resistance and mechanics, high capacity of oxygen stockage (OSC) among others properties. This work deals with the synthesis, characterization and catalytic application of spinel of cobalt and CeO2 with fluorita structure, obtained for method of Pechini and method of Gel-Combustion. The process of Pechini, the puff was obtained at 300 ?C for 2 h in air. In the process of Gel-Combustion the approximately at 350 ?C material was prepared and burnt for Pyrolysis, both had been calcined at 500 ?C, 700 ?C, 900 ?C and 1050 ?C for 2 h in air. The materials of the calcinations had been characterized by TG/DTA, electronic microscopy of sweepings (MEV), spectroscopy of absorption in the infra-red ray (FTIR) and diffraction of X-rays (DRX). The obtained material reaches the phase oxide at 450 oC for Pechini method and 500 ?C for combustion method. The samples were submitted catalytic reaction of n-hexane on superficies of materials. The reactor function in molar ration of 0, 85 mol.h-1.g-1 and temperature of system was 450 ?C. The sample obtained for Pechini and support in alumine of superficial area of 178,63 m2.g-1 calcined at 700 ?C, give results of catalytic conversions of 39 % and the sample obtained for method of gel-combustion and support in alumina of 150 mesh calcined at 500 ?C result 13 % of conversion. Both method were selective specie C1 / O espin?lio de cobalto tem muitas aplica??es pr?ticas devido as suas excelentes propriedades f?sicas e qu?micas tal como catalisador nas rea??es de oxida??o de hidrocarboneto. O CeO2 tem sido utilizado em muitos processos porque designa um material com excelente resist?ncia t?rmica e mec?nica, alta capacidade de estocagem de oxig?nio (OSC) entre outras propriedades. Este trabalho trata da s?ntese e caracteriza??o e aplica??o catal?tica dos ?xidos de cobalto com estrutura espin?lio e CeO2 com estrutura fluorita, obtidos pelo m?todo de Pechini e pelo m?todo de gel-combust?o. No processo Pechini o puff foi obtido a 300 ?C por 2 h em atmosfera ambiente. No processo de gel-combust?o o material foi preparado e queimado a aproximadamente 350 ?C por igni??o espont?nea e, posteriormente, ambos os p?s foram calcinados a 500 ?C, 700 ?C, 900 ?C e 1050 ?C por 2 h em atmosfera ambiente. Os p?s-resultantes das calcina??es foram caracterizados por TG/DTA, microscopia eletr?nica de varredura (MEV), espectroscopia de absor??o no infravermelho (FTIR) e difra??o de raios X (DRX). O material obtido deve atingir a fase ?xida a 450 ?C, para Pechini e 500 ?C para gel-combust?o. As amostras foram submetidas a rea??es catal?ticas de n-hexano sobre os catalisadores de Ce/Co. O reator operou a uma raz?o F/W fluxo molar de reagente por grama de catalisador de 0,85 mol.h-1.g-1 e temperatura no leito de 450 ?C. Para amostras obtidas por Pechini calcinadas a 700 ?C e suportada em alumina com ?rea superficial de 178,63 m2.g-1 obteve-se 39 % de convers?o catal?tica. Para as amostras obtidas pelo m?todo de gel-combust?o calcinadas a 500 ?C e suportada em alumina da Porogel com 150 mesh obteve cerca de 13 % de convers?o catal?tica. Ambos os m?todos foram seletivos a esp?cie C1.

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-05-12T13:11:00Z No. of bitstreams: 1 arquivo total.pdf: 5933598 bytes, checksum: f90080e0529915a4c5c37308259bee89 (MD5) / Made available in DSpace on 2016-05-12T13:11:01Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 5933598 bytes, checksum: f90080e0529915a4c5c37308259bee89 (MD5) Previous issue date: 2015-03-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Zinc stannate (Zn2SnO4) and zinc titanate (Zn2TiO4) are inverse spineltype oxides and stand out due to their optical, electrical, magnetic, semiconductor and photocatalytic properties. In this work, the two materials were combined in order to obtain a solid solution, Zn2Sn1-xTixO4 (x= 0; 0.25; 0.50; 0.75; 1.0), using the modified-Pechini method, in order to evaluate the influence of the Sn4+ ions substitution by Ti4+ ones in the spinel lattice for application as catalysts in the photodiscoloration of the golden yellow remazol. Catalysts were characterized by the X-ray diffraction (XRD), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy and surface area measurements (BET). XRD results showed that the materials presented a high long range order when heat treated at 700 °C, using zinc acetate and pH = 1. IR and Raman spectra confirmed the presence of the [TiO6] and [SnO6] octahedra and (ZnO4) tetrahedron. The parameters used in the dye discoloration were: catalyst mass and irradiation times. The results showed that a higher irradiation time provided a better efficiency. Zn2SnO4 presented the best result, with 81 % of discoloration after 4 h of irradiation. As tin was replaced by titanium in the spinel structure, the catalyst efficiency decreased, achieving 37 % for the Zn2TiO4. / O estanato (Zn2SnO4) e o titanato de zinco (Zn2TiO4) são óxidos do tipo espinélio inverso, destacam-se devido a suas propriedades óticas, elétricas, magnéticas, semicondutoras e fotocatalíticas. Nesse trabalho, os dois materiais foram combinados com a finalidade de obter uma solução sólida, Zn2Sn1-xTixO4, (x= 0; 0,25; 0,50; 0,75; 1,0), utilizando o método Pechini modificado, de modo a investigar a influência da substituição dos íons Sn4+ por íons Ti4+ na rede do espinélio para aplicação como catalisadores na fotodescoloração do corante amarelo remazol ouro. Os catalisadores foram caracterizados pelas técnicas de difração de raios-X (DRX), espectroscopia na região do infravermelho (IV), espectroscopia na região do ultravioleta visível (UV-Vis), espectroscopia Raman e medida de área superficial por BET. Os resultados de DRX mostraram que os materiais apresentaram alta organização a longo alcance, quando calcinados a 700 °C, utilizando acetato de zinco e pH 1. Os espectros de IV e Raman confirmaram a presença dos octaedros [ZnO6], [TiO6],[SnO6] e tetraedro (ZnO4). Os parâmetros utilizados na descoloração do corante foram: massa fixa de catalisador e tempos de radiação. Os resultados mostraram que um maior tempo de radiação proporcionou maior eficiência. O Zn2SnO4 apresentou o melhor resultado, com descoloração de 81% após 4 h de radiação. À medida que o estanho foi substituído pelo titânio na estrutura do espinélio, a eficiência do catalisador foi decrescendo, chegando a 37% para o Zn2TiO4.