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.

<p>In this study, the OMCVD method is demonstrated as a powerful, fast, economic and environmental friendly method to produce a set of PGMelectrocatalysts with different supports, metal content and metal alloys in one step and without the multiple processing stages of impregnation, washing, drying, calcinationsand activation.</p>

In this study, the OMCVD method is demonstrated as a powerful, fast, economic and environmental friendly method to produce a set of PGMelectrocatalysts with different supports, metal content and metal alloys in one step and without the multiple processing stages of impregnation, washing, drying, calcinationsand activation.

ABSTRACT CARBON SUPPORTED AND SURFACTANT STABILIZED METAL NANOPARTICLE CATALYSTS FOR DIRECT METHANOL FUEL CELLS &Ccedil / elik, &Ccedil / aglar M.S., Department of Chemistry Supervisor: Assoc. Prof. Dr. G&uuml / ls&uuml / n G&ouml / kaga&ccedil / August 2005, 72 pages Carbon supported surfactant, such as 1-decanethiol and octadecanethiol, stabilized platinum and platinum/ruthenium species have been prepared recently. In this thesis, for the first time, 1-hexanethiol has been used as an organic stabilizer for the preparation of carbon supported platinum and platinum/ruthenium nanoparticle catalysts. These new catalysts were employed for methanol oxidation reaction, which were used for direct methanol fuel cells. Cyclic voltammetry, X-ray photoelectron spectroscopy and transmission electron microscopy have been used in order to determine the nature of the catalysts. The effect of temperature and time on catalytic activity of catalysts were examined and the maximum catalytic activity was observed for carbon supported 1-hexanethiol stabilized platinum nanoparticle catalyst (with 1:1 thiol/platinum molar ratio) which was heated up at 200oC for 5 hours. The particle size of platinum nanoparticles was determined to be ~ 10 nm in diameter. The size and distribution of metal nanoparticles on carbon support, the Pt/Ru surface composition, the relative amount of Pt(0), Pt(II) and Pt(IV) and the removal of organic surfactant molecules around the metal nanoparticles were found to be important in determining the catalytic activity of electrodes towards methanol oxidation reaction. A significant decrease in catalytic activity was observed for carbon supported 1-hexanethiol stabilized Pt75Ru25 and Pt97Ru3 (with 1:1 thiol/PtRu molar ratio) with respect to carbon supported 1-hexanethiol stabilized Pt (with 1:1 thiol/platinum molar ratio). This result might be due to unremoved stabilizer shell around platinum/ruthenium nanoparticles and increase in amount of Pt(II) and Pt(IV) compared to Pt(0) where the methanol oxidation occured.

Thesis (M.S.); Submitted to Central Missouri State University, Warrensburg, MO (US); 17 Dec 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. Kerr, Kent. NNSA Kansas City Site Office (US) NNSA Kansas City Site Office. 12/17/2004. Report is also available in paper and microfiche from NTIS.

Ce travail est en relation avec la thématique "Energies Propres". Le diméthoxyméthane estun composé adapté au stockage de l’hydrogène pour des applications mobiles, de par saforte teneur en hydrogène, sa très faible toxicité et son faible impact sur l'environnement.De ce fait, des catalyseurs mixtes, à base d’oxyde de vanadium et d’oxyde de titanesulfatés ont été préparés et testés dans la réaction d'oxydation sélective du méthanol enDMM, en vue de la production d'hydrogène. Les propriétés acides et redox de surface ontété corrélées aux performances catalytiques. Les mécanismes de réaction et l'identificationdes facteurs limitant l'activité et la sélectivité des catalyseurs ont été aussi étudiés. / This work is related to the subject “Clean Energy”. Dimethoxymethane (DMM) is asuitable H2 storage material for mobile application because of its high content of hydrogen,extremely low toxicity and environmentally benign. Therefore, sulfated vanadia-titania,sulfated binary vanadia-based and titania-based catalysts were prepared and evaluated inthe reaction of selective oxidation of methanol to DMM and further production ofhydrogen. The surface acidic and redox properties of the studied catalysts were correlatedto their catalytic performance. In addition, the reaction mechanisms and the identificationof factors limiting the activity and selectivity of catalysts were also studied.

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-26Bitstream added on 2014-06-13T20:50:43Z : No. of bitstreams: 1 dib_fh_me_ilha.pdf: 1753088 bytes, checksum: 6f21fa7a5002d96add683e1ad3d75eb9 (MD5) / Neste trabalho são analisadas técnicas de produção do biodiesel a partir do óleo residual reciclado, visando a diversificação da matriz energética brasileira e minimização dos impactos ambientas decorrentes do descarte inadequado desses óleos. Antes do início da produção de biodiesel é necessária a realização de um pré-tratamento deste óleo, o que envolve processos de filtragem, secagem e determinação do teor de acidez, seguida de neutralização, pois de acordo com a porcentagem de ácidos graxos livres presentes na matéria-prima é que os métodos para obtenção dos ésteres são adotados. Primeiramente, foram realizados testes laboratoriais em pequena escala para produção de biodiesel, utilizando como matérias prima o óleo residual reciclado e o óleo de soja degomado para efeito comparativo, tendo sido utilizado hidróxido de sódio como catalisador e experimentadas as rotas metílica e etílica, não tendo sido obtidos resultados satisfatórios neste último caso. Em seguida, a produção foi expandida para uma escala semi-piloto, através da utilização de um reator com capacidade de produzir entre 75 e 80 litros de biodiesel por batelada, sendo neste caso utilizado apenas óleo residual reciclado e processo de transesterificação através da rota metílica, tendo o hidróxido de sódio como catalisador. Depois disso, foi feita a caracterização básica do biodiesel produzido, utilizando-se os equipamentos disponíveis, e foram realizados testes comparativos com outros tipos de biodiesel (Comercial, Vegetal e Animal) e frações de misturas (B25, B50, B75 e B100), tendo como base o biodiesel comercial (B5). Por fim, foram feitos testes com esses combustíveis em um moto-gerador diesel de 6 kVA, variando-se a carga de 0 a 3 kW e determinando-se o consumo específico e a temperatura dos gases de exaustão... / This study analyzes the technical production of biodiesel from waste oil recycling, aimed at diversifying the Brazilian energy matrix and minimizing the environmental impacts of inadequate disposal of waste oils. Before the production of biodiesel it is necessary to perform a previous treatment of this oil, which involves processes of filtration, drying and determination of acidity, followed by neutralization, because according to the percentage of free fatty acids present in the raw material is that the methods for obtaining the esters are defined. Firstly, laboratory tests were performed on a small scale biodiesel production using raw materials like soybean oil and recycle waste soybean oil for comparison, having been used sodium hydroxide as catalyst and tested methyl and ethyl routes, being no obtained satisfactory results in this last case. Then, the production was expanded to a semi-pilot scale, using a reactor that can produces between 75 and 80 liters of biodiesel per batch, being in which case only used recycle waste oil and the transesterification process using methanol route, with sodium hydroxide as catalyst. After that, a basic characterization of biodiesel had been done, using equipment available, and were conducted comparative tests with other types of biodiesel (commercial, vegetable and animal) and fractions of blends (B25, B50, B75 and B100), with commercial biodiesel like base of comparison (B5). Finally, tests were performed with these fuels in a 6 kVA diesel generator set, varying a resistive load from 0 to 3 kW and determining the specific consumption and temperature of the exhaust gases. Analyzing the results, it was verified that the physical and chemical properties measured are within acceptable limits, with density between 0,871 and 0,910 g/ml, viscosity between 3,9 and 6,1 cSt and flash point between 51 and 183°C,... (Complete abstract click electronic access below)

Made available in DSpace on 2016-06-02T19:55:42Z (GMT). No. of bitstreams: 1 6569.pdf: 7813080 bytes, checksum: 5bddbc1ed667ee4456bc01f930d2c15a (MD5) Previous issue date: 2014-11-25 / Financiadora de Estudos e Projetos / study evaluated the production of hydrogen and methane from sugarcane vinasse in anaerobic fluidized bed reactor. Two fluidized bed reactors filled with expanded clay were operated under two different concentrations: R5 (5 gCOD.L-1) and R10 (10 g.CODL-1). During the first stage, glucose was used as the primary carbon source. Along the first step vinasse was added from 0% to 100% of the organic source under HRT of 6 h. In a second step with 100% of sugarcane vinasse, HRT was reduced to 4, 2 and 1 h. In another reactor R15 (15 gCOD.L-1) it was varied the substrate (100% glucose; 50 % glucose/ 50 % vinasse; 100 % vinasse) under HRT of 8 h. All reactors were operated in room temperature and a sludge from the treatment of swine wastewater was used. It was not observed methane production in R15. Hydrogen production rate and hydrogen yield reached, respectively: 0,01 L.h-1.L-1 e 0,10 mmolH2.g-1COD added. In reactors R5 and R10, biogas was formed by H2 and CO2 when glucose was present in the feed. Methane was formed when vinasse became the main substrate. The best operating condition occurred under HRT of 1 h, vinasse 100% at a concentration of 5 gCOD. L-1 with a hydrogen production rate of 0.57 L.h.-1L-1. As regards the yield, the best condition was under HRT of 6 h when the affluent comprised vinasse and glucose (3:1) reaching an yield of 3.07 mmolH2.g-1CODadded. Methane production in acidic conditions showed that the methanogens have adapted to a slightly acidic pH of 4.5. The principal metabolites were ethanol, butyric acid, propionic acid and methanol. Microbial characterization revealed the presence of Prevotella and Megasphaera belonging to the domain Bacteria and Methanobacterium and Methanosphaera belonging to the Archaea domain. / O presente estudo avaliou a produção de hidrogênio e metano a partir de vinhaça de cana-de-açúcar em reator anaeróbio de leito fluidizado. Dois reatores de leito fluidizado preenchidos com argila expandida foram operados sob duas diferentes concentrações de substratos: R5 (5 gDQO.L-1) e R10 (10 gDQO.L-1). Durante a primeira etapa, a glicose foi utilizada como fonte de carbono principal. Em seguida, a vinhaça foi adicionada passando de 0% a 100% da fonte orgânica sob o tempo de detenção hidráulica de 6 h. Numa segunda etapa com 100 % de vinhaça, foi feita a redução do TDH para 4, 2 e 1 h. Um terceiro reator foi empregado com uma concentração maior R15 (15 gDQO.L-1) na qual foi variado o substrato (100% glicose, 50% glicose/50 % vinhaça, 100 % vinhaça) sob o tempo de detenção hidráulica de 8 h. Todos os reatores foram operados em temperatura ambiente e foi utilizado lodo proveniente do tratamento de resíduos da suinocultura. Não foi observada produção de metano no reator R15, apenas H2 e CO2. A produção volumétrica e rendimento de hidrogênio atingiu um máximo de 0,01 L.h-1.L-1 e 0,10 mmolH2.g- 1DQOadicionada na fase de alimentação com vinhaça. Nos reatores R5 e R10 o biogás foi formado por H2 e CO2 quando ainda havia glicose como substrato. Metano foi formado quando a vinhaça se tornou o substrato principal. A melhor condição de operação se deu sob o TDH de 1 h, vinhaça 100 % a uma concentração de 5 gDQO.L-1 quando foi obtida uma produção volumétrica de hidrogênio de 0,57 L.h-1.L-1. No que se refere ao rendimento, a melhor condição se deu sob o TDH de 6 h quando o afluente era constituído por vinhaça e glicose (3:1) e um rendimento de 3,07 mmolH2.g-1DQOadicionada. A produção de metano em condições ácidas mostrou que as metanogênicas consumidoras de hidrogênio se adaptaram ao pH levemente ácido de 4,5. Os principais metabólitos produzidos foram etanol, ácido butírico, ácido propiônico e metanol. A caracterização microbiana revelou a presença de Prevotella e Megasphaera pertencentes ao domínio Bacteria e Methanobacterium e Methanosphaera pertencentes ao domínio Archaea.

Made available in DSpace on 2014-10-09T12:35:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:26Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:42:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:44Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP