This dissertation addresses three research areas in the sol-gel synthesis of functionalmaterials. The first is the kinetics of hydrolysis and condensation of variousorganoalkoxysilanes. Two mathematical models are developed for the sol-gel reaction inbasic conditions with and without nearest-neighbor effects. Effects on reactivity aremeasured with systematic changes in the organic group structure. Replacing onemethoxy group on the precursor with a methyl group decelerates hydrolysis under basicconditions, but accelerates condensation under acidic conditions. Replacing two methylfunctionalprecursors with one ethylene-bridged precursor accelerates hydrolysis in base,but decelerates condensation in acid. Replacing an ethylene bridge with a hexylenebridge always decelerates the sol-gel reactions. Adding an amine into the hexylenebridge always accelerates the sol-gel reactions. These trends show inductive effectsplaying a role only under basic conditions, while steric effects play a role at all pHvalues. The second topic of this thesis is the synthesis of organic-inorganic materialswith bridging or non-bridging organics. The structure of the organic-inorganic hybrids ispartially correlated with the kinetics of the precursors, but the trends indicate anadditional structural role of siloxane cyclization. The third topic of this thesis is thesynthesis of surfactant-templated nanoporous particles. The key to preparing orderedhybrid materials is found to be encouraging aggregation with a surfactant whilediscouraging random condensation of silanes independent of the surfactants. Ahomologous series of cationic pyridinium chloride fluorinated surfactants with varyingchain length are used as pore templates. Typical pore structures such as hexagonal closepackedcylinders are synthesized, as well as new pore structures including random meshphase pores and vesicular silica particles with bilayer or multilayer shells.Fluorosurfactants enable the formation of unusually small pores (1.6 nm) and poresformed from discs or bilayers. In the presence of ethanol, spherical particles with radiallyoriented pores are shown by TEM to form by precipitation of disordered silica-surfactantparticles followed by assembly into organized structures. High-capacity hollow particleswith ordered mesoporous shells are prepared by dual latex / surfactant templating.Finally, we load amine-functionalized mesoporous silica with highly dispersedsuperparamagnetic iron oxide nanoparticles.

Bitumen-derived heavy gas oil contains large amounts of sulfur (~4.0 wt.%) and nitrogen (~0.4 wt.%), which need to be lowered before it becomes suitable as a feedstock for refineries. The most widely used upgrading process is hydrotreating, and the conventional catalyst used for hydrotreating is Ni or Co and Mo or W supported on γ-Al2O3. Additionally, environmentally driven regulations impose strict limits on sulfur and nitrogen levels in transportation fuels. Therefore, the main focus of this work was to enhance the activity of a NiMo supported catalyst through its modification and to improve its selectivity to removal of bulky sulfur- and nitrogen-containing compounds from heavy gas oil under industrial hydrotreating conditions. This work was divided into four phases, and this thesis summarizes the research outcomes of each phase. The first phase examined the effects of chelating ligands, specifically, ethylenediaminetetraacetic acid (EDTA), on hydrotreating activity and the sulfidation mechanism. EDTA was seen to have a beneficial effect on hydrotreating activity. Detailed mechanistic aspects of interactions between support and EDTA, EDTA and metallic species, support and metal, support and active phase, and metallic species and metallic species at different reaction conditions, were also studied. Characterization by XANES revealed that the presence of a chelating agent delayed nickel sulfidation, which was the main cause of improvement in hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities. It also showed that EDTA plays a role in redistribution of active phases during sulfidation and favors the formation of octahedral molybdenum oxides. The second phase studied the effects of support modification and combinations of different supports and EDTA. In this phase, several mesoporous materials, including M-SBA-15 (M= Al, Ti and Zr), mesoporous mixed metal oxides (TiO2-Al2O3, ZrO2-Al2O3 andSnO2-Al2O3) and mesoporous metal oxides (ZrO2, Al2O3), were synthesized and used as support materials for a NiMo catalyst. NiMo/M-SBA-15 catalysts showed higher HDS and HDN activities and, the increase in activity is attributed to incorporation of heteroatoms in an SBA-15 matrix, which resulted in increase in metal support interaction, acidic strength and dispersion of active metals. The addition of EDTA to these catalysts helps in the formation of octahedral molybdenum oxide, which are easily reducible during sulfidation. This is evident from the XANES Mo LIII-edge study of the oxide catalysts. The increase in hydrodenitrogenation (HDN), hydrodesulfurization (HDS) and hydrodearomatization (HDA) activities as compared to that shown by the NiMo/γ-Al2O3 catalyst were also observed on addition of EDTA in large-pore, high-surface-area mesoporous zirconia supported NiMo catalysts. The incorporation of different metal oxides in alumina, as in the case of mixed metal oxides, resulted in a change in acidic strength and metal support interactions. It was observed with acridine-FTIR analysis that the catalysts with higher acidic strength tightly held acridine at high temperatures. This implies that catalysts with higher acidity are prone to inhibition by nitrogen-containing compounds present in feed, which will affect catalytic activity. The HDS and HDN activities for hydrotreating of heavy gas oil suggest that mesoporous alumina and titania-alumina supported catalysts perform better as compared to the conventional NiMo/γ-Al2O3 catalyst. Therefore, the effects of EDTA to Ni molar ratio (EDTA/Ni = 0 to 2) on the activities of the NiMo/MesoAl2O3 and NiMo/MesoTiO2-Al2O3 catalysts were studied, and EDTA was observed to have a negative impact on catalytic activity for these catalysts. This is attributed to a decrease in the active metal dispersion in these catalysts caused by the addition of EDTA. The catalysts NiMo/MesoAl2O3 and NiMo/MesoTiO2-Al2O3 without EDTA showed high active metal dispersion due to their high surface area and ordered structure. The third phase studied the combined effects of phosphorus and EDTA on the hydrotreating activity of NiMo supported catalysts. The effects of method of phosphorus addition (sequential and co-impregnation method) were also studied. When phosphorus was added using a co-impregnation method, as in the catalyst NiMoP/MesoAl2O3(CI), an increase in HDN, HDA and HDS activities was observed. However, the catalysts containing both EDTA and phosphorus showed a decrease in HDS and HDN activities. The fourth phase included a kinetic study using the Power Law and L-H models. The catalyst, NiMoP/mesoAl2O3(CI), was found to have higher HDN and HDS activities as compared to a conventional γ-Al2O3 supported catalyst containing phosphorus.

The removal of trace amounts of acetylene in ethylene streams is a high-volume industrial process that must possess high selectivity of alkyne hydrogenation over hydrogenation of alkenes. Current technology uses metallic nanoparticles, typically palladium or platinum, for acetylene removal. However, problems arise due to the deactivation of the catalysts at high temperatures as well as low selectivities at high conversions. Pore expanded MCM-41 is synthesized via a two-step strategy in which MCM-41 was prepared via cetyltrimethylammonium bromide (CTMABr) followed by the hydrothermal treatment with N,N-dimethyldecylamine (DMDA). This material was washed with ethanol to remove DMDA, or calcined to remove both surfactants. PE-MCM-41 based materials were impregnated with palladium, gold, and palladium-gold nanoparticles. The removal of DMDA had an effect on both the conversion and selectivity, in which they were found to drop significantly. However, by using the bimetallic PdAu catalysts, higher selectivity could be achieved due to increased electron density.

Submitted by RAFAEL MIGUEL SÁBIO null (rafaelmsabio@gmail.com) on 2016-11-01T21:14:55Z No. of bitstreams: 1 THESE RAFAEL MIGUEL SABIO 26_10_2016.pdf: 9769437 bytes, checksum: 37a38ed4b54498b696d4fe43ebcdfa2e (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-10T13:19:03Z (GMT) No. of bitstreams: 1 sabio_rm_dr_araiq_par.pdf: 1635130 bytes, checksum: e5de0aa69e20b9d8d68afedc85cab297 (MD5) / Made available in DSpace on 2016-11-10T13:19:03Z (GMT). No. of bitstreams: 1 sabio_rm_dr_araiq_par.pdf: 1635130 bytes, checksum: e5de0aa69e20b9d8d68afedc85cab297 (MD5) Previous issue date: 2016-10-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Le design de complexes luminescents hétérobimétalliques a suscité ces dernières années un intérêt croissant en raison de leurs propriétés photophysiques uniques. Dans ces complexes de lanthanide (Nd (III) et Yb (III)) associé à des chromophores du bloc d, la forte émission des métaux de transition dans le visible est utilisée pour sensibiliser de façon efficace les niveaux f-f des lanthanides(III) qui émettent à leur tour dans le visible ou l’IR selon les terres rares. Plus spécifiquement l’attention s’est focalisée sur le développement de complexes hétérobimétalliques d-f pour l’émission dans le proche infrarouge (NIR). En effet le proche infrarouge, comparé à l’UV, pénètre plus facilement les tissus biologiques humains notamment la peau. Bien que de telles propriétés confèrent à ces complexes bimétalliques un fort potentiel pour le diagnostic médical, aucun complexe hétérobimétallique d-f greffé de façon covalente à une matrice de silice n’a été décrit. Dans ce travail de nouveaux complexes hétérobimétalliques d-f contenant des ligands silylés ont été préparés et greffés sur la silice. Les complexes monomères [Ru(bpy)2(bpmd)]Cl2 (noté Ru), [Ru(bpy)(bpy-Si)(bpmd)]Cl2 (noté RuL) et [Ln(TTA-Si)3] (noté LnL3) et les complexes hétérobimétalliques d-f Ru-LnL3 et Ln-RuL (Ln = Nd3+, Yb3+) ont été préparés. La caractérisation des complexes a été effectuée par spectroscopie Raman, RMN 1H et 13C RMN. Les spectres RMN 1D 1H et 13C NMR ainsi que 2D de corrélation HSQC confirment les structures proposées. L’étude des propriétés photophysiques met en évidence l’émission de l’élément lanthanide dans le proche infrarouge ainsi que l'efficacité du processus de transfert d'énergie Ru-Ln qui est facilité par le ligand (2,2'-bipyrimidine). Les mesures de durée de vie et de rendement quantique (ET) pour le transfert d'énergie indiquent des valeurs remarquables comprises entre 30 et 84 %. La valeur du rendement quantique (ET) du complexe d'Yb-RuL, 73,4 %, est à ce jour la plus grande valeur rapportée pour un complexe hétérobimétallique Ru (II)-Yb (III). Le greffage sur différentes matrices de silice, mésoporeuse SiO2 ou dense SiO2 d, a été réalisé. Les nanohybrides SiO2-RuL, SiO2-NdL3 et SiO2-YbL3 ont été obtenus avec des taux de greffage allant de 0,08 à 0,18 mmol de complexe par gramme de silice. SiO2-RuNd et SiO2- RuYb ont été obtenus par greffage simultané des complexes silylés monomères de ruthénium et de lanthanide, des taux de greffage de 0,10 à 0,16 mmol.g-1 ont été obtenus, respectivement. Les rendements quantiques ET de transfert d’énergie des nanohybrides SiO2-RuNd et SiO2-RuYb sont respectivement de 40 and 27,5 %. La valeur remarquable obtenue pour le nanohybride impliquant le néodyme, SiO2-RuNd, s’explique par bonne adéquation entre les niveaux d’énergie du donneur et de l’accepteur. Les nanohybrides SiO2- RuYbL3, SiO2-YbRuL, SiO2d-YbRuL et SiO2-NdRuL ont été obtenus par greffage des complexes silylés hétérobimétallic d-f élaborés dans ce travail, les taux de greffage, de 0,03 à 0,17 mmol.g-1 permettent d’envisager une fonctionnalisation chimique ultérieure de ces nanoobjets. Les propriétés de luminescence de ces nanohybrides sont similaires à celles des complexes non greffés hormis pour SiO2-YbRuL and SiO2d-YbRuL qui présentent des profils de luminescence différents comparés au complexe libre Yb—RuL. Le greffage à l'intérieur des pores de la silice pourrait éviter le processus de désactivation de la luminescent contrairement au greffage sur la matrice de silice dense. Les propriétés photophysiques associées à la morphologie et à la stabilité de la matrice de silice mésoporeuse permettent d’envisager l’utilisation de ces nouveaux nanohybrides luminescents dans le proche infrarouge comme nanosondes ou nanomarqueurs de systèmes biologiques. / The design of heterobimetallic luminescent complexes has gained growing interest in recent years due to their unique photophysical properties. More specifically, the development of heterobimetallic complexes using d-block chromophores to sensitize the near-infrared (NIR) emission of lanthanide complexes (such as Nd(III) and Yb(III)) has received significant attention taking into account their longer emission wavelengths and the interest of the NIR emission which penetrates human tissue more effectively than UV light. These properties give them potential applications in medical diagnostics or biomedical assays. Transitions to excited state levels of transition metal complexes occurring in the visible and characterized by large absorption coefficients, could efficiently sensitize f-f levels of Ln(III) ions. In this work new d-f heterobimetallic complexes containing silylated ligands were prepared supported on silica materials. [Ru(bpy)2(bpmd)]Cl2 (labeled Ru), [Ru(bpy)(bpy-Si)(bpmd)]Cl2 (labeled RuL) and [Ln(TTA-Si)3] (labeled LnL3) and d-f heterobimetallic complexes, Ru—LnL3 and Ln—RuL (Ln = Nd3+, Yb3+) were prepared. Structural characterization was carried out by Raman Scattering, 1H and 13C NMR spectroscopies. Results obtained from 1H-13C HMBC and HSQC correlation NMR spectra confirm the formation of proposed complexes. Photophysical properties studies highlight the efficiency of Ru—Ln energy transfer processes in NIR-emitting lanthanide complexes mediated by conjugated bridging ligand (2,2'-bipyrimidine). Lifetime measurements were carried out and values of quantum yield for energy transfer (ET) between 30 and 84 % could be evaluated. ET of 73.4 % obtained for the Yb—RuL complex is the largest value reported for Ru(II)—Yb(III) heterobimetallic complexes so far. Grafting on different silica matrix was also demonstrated. SiO2-Ru, SiO2-NdL3 and SiO2-YbL3 nanohybrids were obtained with grafting efficiencies from 0.08 to 0.18 mmol g-1 of silica. SiO2-RuNd and SiO2-RuYb were performed from simultaneous grafting of ruthenium and lanthanides silylated complexes. Grafting efficiencies from 0.10 to 0.16 were obtained. ET of 40 and 27.5 % were obtained from SiO2-RuNd and SiO2-RuYb, respectively. The higher values observed for the Nd(III) nanohybrid is well explained by the matching of donor and acceptor energy levels. SiO2-RuYbL3, SiO2-YbRuL, SiO2 d-YbRuL and SiO2-NdRuL were carried out from grafting of d-f heterobimetallic silylated complexes. Grafting efficiencies from 0.03 to 0.17 were obtained. Luminescent properties from these nanohybrids were similar to the free complexes. However the SiO2-YbRuL and SiO2 d-YbRuL showed distinct luminescent profiles compared with the free Yb—RuL. The grafting inside the mesoporous channels may prevent luminescent desactivation processes comparing to the dense silica matrix. The photophysical properties associated with the morphology and stability of the mesoporous silica matrix allow suggesting these new NIR luminescent nanohybrids as nanoprobes or nanomarkers in biomedicine.

CORREIA, L. M. Fe2O3 ou Co3O4 suportados em sílicas mesoporosas modificadas com NH4F e Ti para adsorção de benzotiofeno e reação de oxidação catalítica seletiva parcial de H2S a S. 2017. 233 f. Tese (Doutorado em Engenharia Química)-Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2017. / Submitted by Hohana Sanders (hohanasanders@hotmail.com) on 2017-10-03T18:25:12Z No. of bitstreams: 1 2017_tese_lmcorreia.pdf: 3519700 bytes, checksum: 80fb75064a529c39bee1587404389fd8 (MD5) / Approved for entry into archive by Marlene Sousa (mmarlene@ufc.br) on 2017-11-08T14:44:39Z (GMT) No. of bitstreams: 1 2017_tese_lmcorreia.pdf: 3519700 bytes, checksum: 80fb75064a529c39bee1587404389fd8 (MD5) / Made available in DSpace on 2017-11-08T14:44:39Z (GMT). No. of bitstreams: 1 2017_tese_lmcorreia.pdf: 3519700 bytes, checksum: 80fb75064a529c39bee1587404389fd8 (MD5) Previous issue date: 2017-07-31 / The presence of sulfur (S) in automotive fuels must be retrain, once it generates air pollution and promotes damage to the motor (corrosion), affecting the health of living beings. The conventional process of hydrodesulfurization (HDS) for sulfuric compounds removal, used by petrochemical industries, generates large amount of H2S, which can be used in selective partial oxidation reaction of H2S to S. The HDS treatment process is not effective to remove refractory compounds at low concentrations of S, making polish techniques, such as adsorption, necessary due to environmental constraints increase. This situation has led to a need of deeper research in the area of sulfur compounds removal in fossil fuels (gas and diesel). Thus, the development of methodologies to prepare and characterize new adsorbents with high sulfur removal are necessary. The adsorption of BT (standard organic molecule contained in gas and diesel) was investigated using a regular mesoporous silica SBA-15 type and modified with NH4F, and impregnated with Fe and Co respectively. The experiments were done in batch, with different initial BT concentrations (3-15 mmol.L-1) at different temperatures (30 °C, 40 °C and 50 °C). In the second part of the research, the H2S was partially oxidized to S and SO2 using a tubular fixed bed catalytic reactor, containing mesoporous silica HMS, SBA-15, and MCM-41 modified with NH4F and Ti, and respectively Fe2O3 and Co3O4. The catalytic tests were conducted at 180 °C and 170 oC. Reactional conditions were a catalyst mass of 100 mg (40-60 mesh), operating with a 125 mL.min-1 total flow, with molar ratio H2S/Air/He (1/5/94). The brackets, adsorbents and active phases of mesoporous catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), adsorption and desorption isotherms at -196°C, x-ray photoeletronic spectroscopy (XPS), Fourier transform infrared (FTIR), Elemental analysis (CHNS) and spectroscopy of UV-visible region. The results show that mycotoxin adsorbents are promising for the hydrodesulfurization process for BT removal, especially, the sample (15Co/SBA-15/NH4F). All the prepared catalysts are active and promising for the elementary S production. The most stable catalyst was 15Fe/MCM-41, obtaining conversion values of H2S (89.72%), selectivity of S (96.19%), and selectivity of SO2 (3.81%) at 180 °C and 360 min of reaction time in the H2S to S selective oxidation partial reaction in gas phase / A presença de enxofre (S) nos combustíveis automotivos deve ser combatida, uma vez que gera a poluição atmosférica e traz prejuízos ao motor (corrosão), afetando também à saúde dos seres vivos. O processo convencional de hidrodessulfurização (HDS) para remoção dos compostos de S, utilizado pelas indústrias petroquímicas, gera elevada quantidade de H2S, o qual pode ser utilizado na reação de oxidação seletiva parcial de H2S a S. O processo de tratamento por HDS não é eficaz para remoção de compostos refratários em baixas concentrações de S, o que torna necessário a técnicas de acabamento como a adsorção, devido a um aumento nas restrições ambientais. Essa situação tem levado a uma necessidade de maiores pesquisas na área de remoção de sulfurados nos combustíveis (gasolina e diesel). Assim, busca-se desenvolver metodologias para preparar e caracterizar novos adsorventes com elevada capacidade de remoção de enxofre. A adsorção de BT (molécula orgânica modelo contida na gasolina e diesel) foi investigada utilizando-se sílicas mesoporosas do tipo SBA-15 e modificadas com NH4F, e impregnadas respectivamente com Fe e Co. Os experimentos foram feitos em batelada, com diferentes concentrações iniciais de BT (3-15 mmol/L) e temperaturas distintas (30 oC, 40 oC e 50 oC). Na segunda parte da pesquisa o H2S foi parcialmente oxidado a S e SO2 utilizando um reator catalítico de leito fixo do tipo tubular, contendo sílica mesoporosa do tipo HMS, SBA-15, e MCM-41 modificadas com NH4F e Ti, e respectivamente Fe2O3 e Co3O4. Os testes catalíticos foram conduzidos a uma temperatura de reação de 180 ºC e 170 oC. As condições reacionais foram massa do catalisador de 100 mg (40-60 mesh), operando com uma vazão total de 125 mL min-1, com razão molar H2S/Ar/He (1/5/94). Os suportes, adsorventes e as fases ativas dos catalisadores mesoporosos foram caracterizados por difração de raios-X (DRX), microscopia eletrônica de transmissão (MET), isotermas de adsorção e dessorção a -196 oC, espetroscopia fotoeletrônica de raios-X (XPS), infravermelho com transformada de Fourier (FTIR), análise elementar (CHNS) e espectroscopia da região do UV-visível. Os resultados demonstram que os adsorventes são promissores para o processo de hidrodessulfurização para a remoção da molécula de BT, especialmente, a amostra (15Co/SBA-15/NH4F). Todos os catalisadores preparados são ativos e promissores para produção de S elementar. O catalisador mais estável foi 15Fe/MCM-41, obtendo-se valores de conversão de H2S (89,72%), seletividade a S (96,19%), e seletividade a SO2 (3,81%) na temperatura de 180 oC e tempo reacional de 360 min na reação parcial de oxidação seletiva de H2S a S em fase gás

Made available in DSpace on 2016-06-02T19:56:58Z (GMT). No. of bitstreams: 1 6661.pdf: 7538464 bytes, checksum: 48b2c202273cc209a796ea8ef2da1b35 (MD5) Previous issue date: 2015-02-23 / Universidade Federal de Sao Carlos / In recent years there has been growing interest in studies on the use of heterogeneous catalysts in the biodiesel production, since such materials have some advantages over homogeneous catalysts such as ease of separation of product generated and the possibility of being reused. Among these catalysts, it is important to emphasize the mesoporous molecular sieves, since they have some advantages that enable its catalytic application. This study aimed to synthesize spheres of hybrid silica, with mesoporous occluded by the driver structure (CTA-SiO2), and to investigate the influence of different alcohols in the properties of these materials and evaluate their catalytic activity in the transesterification reaction. The mesoporous silicas were synthesized with varying the length of the alkyl chain (C1-C3) and amount of alcohol in the reaction mixture. The silicas were characterized by different techniques, such as X-ray scattering at small angles (SAXS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis. The results showed that the structure and morphology of the mesoporous silica containing organic driver may be controlled during synthesis by varying alcohol content, leading to the formation of materials with different phases, levels of organization and morphology, with the best results obtained from the samples synthesized with methanol and ethanol. For the evaluation of activity and catalytic stability, hybrid silicas were tested in transesterification reaction between ethyl acetate and methanol. The materials showed activity, and when the pore structure is well organized, larger amount of catalytic sites is available resulting in higher conversions. Thus synthesized materials with lower amounts of alcohol had higher catalytic activity compared with other materials. Silicas synthesized showed little catalytic stability compared to successive uses in the transesterification reaction. Thus, materials synthesized with the use of smaller amounts of alcohol tended to stability in comparison to other samples. Part of the activity is due to the presence of basic species formed as a result of leaching of cations CTA+, promoting the reaction also in the homogeneous phase. / Nos últimos anos tem sido crescente o interesse por estudos sobre o emprego de catalisadores heterogêneos na produção de biodiesel, uma vez que esses materiais possuem algumas vantagens em relação à catálise homogênea, tais como a facilidade de separação dos produtos gerados e possibilidade de serem reutilizados. Dentre esses catalisadores, torna-se importante salientar as peneiras moleculares mesoporosas, pois apresentam algumas vantagens que viabilizam sua aplicação catalítica. O presente estudo teve como objetivo sintetizar sílicas híbridas em formato de esferas, com mesoporos ocluídos pelo direcionador de estrutura (CTA-SiO2), bem como investigar a influência de diferentes álcoois nas propriedades desses materiais e avaliar sua atividade catalítica na reação de transesterificação. As sílicas mesoporosas foram sintetizadas com variação do comprimento da cadeia alquílica (C1-C3) e quantidade de álcool na mistura reacional. Foram caracterizadas por diferentes técnicas, como: espalhamento de raios X a ângulos pequenos (SAXS), difratometria de raios- X (DRX), microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (MET) e análise termogravimétrica. Os resultados mostraram que a estrutura e morfologia das sílicas mesoporosas contendo direcionador orgânico podem ser controladas durante a síntese através da variação do teor de álcool, levando à formação de materiais com diferentes fases, níveis de organização e morfologia, sendo os melhores resultados obtidos a partir das amostras sintetizadas com metanol e etanol. Para avaliação da atividade e a estabilidade catalítica, as sílicas híbridas foram testadas na reação de transesterificação entre o acetato de etila e metanol. Os materiais apresentaram atividade, sendo que quando a estrutura dos poros é bem organizada, maior quantidade de sítios catalíticos fica disponível resultando em maiores conversões. Consequentemente, os materiais sintetizados com menores teores de álcool apresentaram maior atividade catalítica em comparação com os demais materiais. As sílicas sintetizadas mostraram pouca estabilidade catalítica frente a sucessivos usos na reação de transesterificação. Assim, os materiais sintetizados com emprego de menores teores de álcool apresentaram uma tendência à estabilidade em relação às demais amostras. Parte da atividade se deve à presença de espécies básicas formadas em consequência da lixiviação dos cátions CTA+, promovendo a reação também na fase homogênea.

Made available in DSpace on 2014-06-11T19:35:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-12Bitstream added on 2014-06-13T18:46:22Z : No. of bitstreams: 1 rocha_la_dr_araiq.pdf: 3758896 bytes, checksum: 8f9b1dddc8f92a0c77915bd317de357f (MD5) / Partículas esféricas de sílica mesoporosa foram obtidas a partir da síntese “template” pelo processo de pirólise de aerossol. O processo foi otimizado para a obtenção de materiais mesoporosos sem resíduos orgânicos e preparados em uma única etapa, eliminando assim, a longa etapa de remoção do surfactante na metodologia tradicional (tratamento térmico ou extração soxhlet, podendo durar dezenas de horas). A otimização do processo de pirólise de aerossol proposta nesta tese reduziu este tempo para apenas alguns minutos. Os materiais apresentaram uma área superficial (BET) de até 1028 m2 .g-1 , com volume de poros (BJH) de 0,58 cm3 .g-1 . Os difratogramas de raios-X indicaram um alto grau de organização com um arranjo hexagonal de poros, confirmado também pela microscopia eletrônica de transmissão. Além disto, bandas características de grupos orgânicos não foram observadas nos espectros de absorção na região do infra-vermelho para as amostras obtidas acima de 600ºC. Amostras dopadas com íons Eu3+ também foram preparadas durante a tese. A análise por espectroscopia de luminescência, para íons Eu3+ , indicou que o íon está encapsulado nos canais mesoporosos sem prévia modificação química da matriz. Posteriormente, moléculas de 1,10- Fenantrolina foram coordenadas ao íon Eu3+ aumentando a faixa espectral de excitação do íon (efeito antena). Além disto, partículas luminescentes também foram obtidas pela incorporação do complexo Eu(fod)3 ou rodamina-B nos poros das matrizes. Finalmente, testes de recobrimento (core shell, SiO2 mesoporoso-SiO2) das partículas luminescentes foram realizados e os resultados indicaram que independentemente da espessura obtida pelo processo de recobrimento, o grau de organização dos poros e a fotoluminescência não sofreram alterações / Spherical mesoporous silica particles were obtained using the template synthesis by spray pyrolysis process. The process was optimized for the preparation of the mesoporous materials in one-pot route without organic residues, eliminating thus, the long process of removal of the surfactant, usually used in the available methods (heat treatment or soxhlet extraction, which require several hours or days). The one- pot route proposed in this thesis reduced the extraction process to only a several minutes. These materials presented a surface area value (BET) of 1028m2 .g-1 and pore volume (BJH) was 0,58 cm3 .g-1 . The X-ray diffraction patterns and the transmission electronic micrographs show an ordered typical p6mm 2D hexagonal mesostructure. Characteristics bands of organic groups were not observed in the infra-red absorption spectra for the samples obtained at 600ºC. Moreover, SiO2 mesoporous doped with Eu3+ ions were also prepared. Luminescence data suggest that the Eu3+ ions were successful encapsulated into the channels of mesoporous silica without any preliminary chemical modification of the matrix. Moreover, extra ligands such as 1,10-Phenantroline can be further coordinated, increasing the spectral range excitation (antenna effect). Furthermore, luminescent particles were also prepared by the wet impregnation of Eu(fod)3 complex and rhodamine-B molecules. Finally, tests of coating (core shell, SiO2 mesoporous-SiO2) of luminescent particles had been carried through and the The results obtained show spherical shape and the observation of a highly ordered hexagonal array of mesochannels further confirms the 2D hexagonal p6m structure. Luminescence results reveal that rhodamine-B has been successfully encapsulated into the channels of mesoporous particles. Silica coating has been observed in TEM measurements

abstract: This dissertation provides a fundamental understanding of the properties of mesoporous carbon based materials and the utilization of those properties into different applications such as electrodes materials for super capacitors, adsorbents for water treatments and biosensors. The thickness of mesoporous carbon films on Si substrates are measured by Ellipsometry method and pore size distribution has been calculated by Kelvin equation based on toluene adsorption and desorption isotherms monitored by Ellipsometer. The addition of organometallics cobalt and vanalyl acetylacetonate in the synthesis precursor leads to the metal oxides in the carbon framework, which largely decreased the shrink of the framework during carbonization, resulting in an increase in the average pore size. In addition to the structural changes, the introduction of metal oxides into mesoporous carbon framework greatly enhances the electrochemical performance as a result of their pseudocapacitance. Also, after the addition of Co into the framework, the contraction of mesoporous powders decreased significantly and the capacitance increased prominently because of the solidification function of CoO nanoparticles. When carbon-cobalt composites are used as adsorbent, the adsorption capacity of dye pollutant in water is remarkably higher (90 mg/g) after adding Co than the mesoporous carbon powder (2 mg/g). Furthermore, the surface area and pore size of mesoporous composites can be greatly increased by addition of tetraethyl orthosilicate into the precursor with subsequent etching, which leads to a dramatic increase in the adsorption capacity from 90 mg/g up to 1151 mg/g. When used as electrode materials for amperometric biosensors, mesoporous carbons showed good sensitivity, selectivity and stability. And fluorine-free and low-cost poly (methacrylate)s have been developed as binders for screen printed biosensors. With using only 5wt% of poly (hydroxybutyl methacrylate), the glucose sensor maintained mechanical integrity and exhibited excellent sensitivity on detecting glucose level in whole rabbit blood. Furthermore, extremely high surface area mesoporous carbons have been synthesized by introducing inorganic Si precursor during self-assembly, which effectively determined norepinephrine at very low concentrations. / Dissertation/Thesis / Ph.D. Chemical Engineering 2012

Orientador: Claudio Airoldi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-17T19:54:52Z (GMT). No. of bitstreams: 1 Badshah_Syed_D.pdf: 4398020 bytes, checksum: 41352eaf93af6ab6efa1bf20fb83ffd9 (MD5) Previous issue date: 2011 / Resumo: No presente trabalho, híbridos inorgânico-orgânicos nanoestruturados de sílica mesoporosa e de filossilicatos de magnésio lamelares com estrutura similar ao talco foram sintetizados e caracterizados. A máxima capacidade sorptiva de cátions dos híbridos e as características energéticas das interações dos cátions com centros básicos, na interface sólido/líquido, foram também estudadas. A sílica mesoporosa análoga aos materiais SBA-15 tem sido sintetizada por meio do tribloco co-polímero EO20-PO70 -EO20 (P123 - Pluronic®), que atua como um agente direcionador estrutural. Os materiais SBA-15 sintetizados foram funcionalizados com vários agentes sililantes, os quais apresentam os seguintes grupos funcionais: amida, nitrila e marfolina ou base de Schiff do anel tiofênico. Os agentes sililantes com os grupos funcionais mencionados acima foram sintetizados por meio de reações de adição de Michael do aceptor de Michael a,b - insaturado (acrilamida, acrilonitrila e 4- acriloilmarfolina), ou por meio da reação de base de Schiff do 2-tiofenocaboxaldeído com os agentes sililantes aminados, comercialmente disponíveis. As técnicas de espalhamento de raios X a baixa ângulo (SAXS) e de adsorção/desorção de nitrogênio para a SBA-15 pura e a SBA-15 funcionalizada mostraram um arranjo estrutural hexagonal bem-ordenado nos materiais. Os filossilicatos lamelares híbridos com diferentes porções orgânicas presentes dentro dos nanoespaços lamelares foram sintetizados por meio de reações sol-gel de uma única etapa. Com esse intuito, os agentes sililantes com vários grupos funcionais (tiopropanamida, tiocarbamato, nitrila e base de Schiff ou anel tiofênico) foram sintetizados e reagiram com uma solução metanólica de nitrato de magnésio, sob condições básicas. A difratometria de raios X indicou distâncias basais maiores de que 1 nm para os filossilicatos híbridos sintéticos. A técnica de difração de raios X também mostrou que a estrutura inorgânica dos filossilicatos híbridos era similar àquela do talco natural. A estrutura inorgânica do filossilicato híbrido é composta de camadas octaédricas ocupadas pelo átomo de magnésio hexacoordenado presentes entre duas camadas tetraédricas silícicas, em que a porção orgânica está covalentemente ligada à camada tetraédrica da estrutura em camadas. A integridade das porções orgânicas ligadas à rede inorgânica da sílica mesoporosa ou dos filossilicatos foi confirmada por meio da Espectroscopia no Infravermelho com transformada de Fourier e por meio da técnica de Ressonância Magnética no estado sólido para os núcleos Si e C. A máxima incorporação de porções orgânicas foi determinada por meio da análise elementar. As porções orgânicas ligadas aos materiais híbridos contêm: nitrogênio, oxigênio e enxofre, os quais correspondem aos sítios básicos disponíveis para a remoção de espécies como: Pb, Cu, Cd e Ni. As capacidades sorptivas máximas dos materiais híbridos para tais cátions foram obtidas por meio de Isotermas de adsorção de Langmuir. Os resultados revelam que os filossilicatos lamelares híbridos apresentam elevada capacidade para remoção de cátions em comparação com os materiais SBA-15, devido ao elevado grau de funcionalização. A energética das interações entre os cátions e os centros básicos ao longo da interface sólido/líquido foram determinadas através da microcalorimetria. As variações negativas da energia de Gibbs, de entalpia e os valores positivos de variação entrópica indicam interações espontâneas e favoráveis entre os sólidos e os íons metálicos. Esses resultados favoráveis indicam que os híbridos sintetizados podem ser úteis na remoção de cátions tóxicos de soluções aquosas, auxiliando na despoluição de ecossistemas / Abstract: In the present work, nanostructured inorganic-organic hybrids based on mesoporous silica and lamellar magnesium phyllosilicates with talc-like structure were synthesized and characterized. The maximum cations sorption capacity of the hybrids and energetic features from cation- basic center interactions at the solid liquid interface were also studied. The mesoporous silica analogous to SBA-15 materials has been synthesized through the triblock co-polymer EO20-PO70 -EO20 (P123 ¿ Pluronic®) as a structured directing agent. The synthesized SBA-15 materials were functionalized with various silylating agents having organic functional groups of amide, nitrile, and marpholine or Schiff base of thiophenic ring. The silylating agents with the aforementioned functional groups were synthesized either by the Michael addition reactions of a,b-unsaturated Michael acceptor (acrylamide, acrylonitrile and 4-acryloylmarpholine) or by the Schiff base reaction of 2-thiophenecaboxaldehyde with commercially available aminated silylating agents. Small angle X-ray scattering (SAXS) and nitrogen adsorption/desorption experiments for both SBA-15 and functionalized SBA-15 showed well-ordered hexagonal array structure. The lamellar phyllosilicates hybrids with different organic moieties inside the lamellar nanospaces were synthesized through a single step sol-gel reaction. For this purpose, silylating agents with various functional groups (thiopropanamide, thiocarbamate, nitrile and Schiff base of thiophenic ring) were synthesized and reacted with methanolic solution of magnesium nitrate under basic conditions. The X-ray diffraction showed basal distances of more than 1 nanometer for the synthetic hybrid phyllosilicates. The XRD also showed that the inorganic structure of the hybrid phyllosilicates was similar to that of natural talc. The inorganic network of the hybrid phyllosilicate is composed of octahedral sheet occupied by hexacoordinated magnesium atom sandwiched between two tetrahedral silicic sheets, and the organic moiety is covalently bonded to the tetrahedral sheet of the layered structure. The integrity of organic moieties attached to the inorganic network of mesoporous silica or phyllosilicates was confirmed by the Fourier transform infrared spectroscopy and nuclear magnetic resonance in the solid-state for the Si and C nuclei. The maximum incorporation of organic moieties was determined through elemental analysis. The attached organic moieties of the hybrid materials contain nitrogen, oxygen or sulfur basic centers available for divalent lead, copper, cadmium and nickel cation removal. The maximum sorption capacities of the hybrids for such cations were obtained through Langmuir adsorption isotherms. The results reveal that the lamellar magnesium phyllosilicate hybrids present high capacity for cations removal as compared to functionalized SBA-15 materials, due to a high degree of functionalization. The energetic of cation-basic centers interactions at the solid/liquid interface were determined through microcalorimetry. The negative Gibbs energy, exothermic enthalpy and positive entropic values indicate spontaneous and favorable interactions between the solids and metal ions. These favorable results indicated that the synthesized hybrids can be useful for removal of toxic cations from aqueous solutions for the improvement of ecosystem / Doutorado / Quimica Inorganica / Doutor em Ciências

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A exigÃncia de um maior controle na emissÃo de poluentes de automÃveis, com uma reduÃÃo na emissÃo de enxofre, tem levado a um intenso esforÃo de pesquisas sobre tÃcnicas de remoÃÃo de sulfurados nos combustÃveis. Nos Ãltimos anos, a adsorÃÃo à vista como uma tÃcnica alternativa adequada para atingir os nÃveis de dessulfurizaÃÃo das correntes das unidades de processo de hidrodessulfurizaÃÃo (HDS). O processo HDS à muito eficiente na remoÃÃo de mercaptanas e dissulfetos, porÃm maior severidade seria necessÃria para converter as molÃculas cÃclicas de enxofre, tais como tiofenos e benzotiofenos. Devido ao tamanho volumoso destes compostos refratÃrios de enxofre, adsorventes mesoporosos sÃo vistos como mais adequado para a adsorÃÃo do que sÃlidos microporosos convencionais, tais como zeÃlitas. A dessulfurizaÃÃo por adsorÃÃo com adsorventes modificados e seletivos à um processo alternativo promissor com relaÃÃo à hidrodessulfurizaÃÃo convencional por se tratar de um processo que nÃo necessita de condiÃÃes severas de operaÃÃo que comprometam a octanagem da gasolina e o custo final de operaÃÃo. Neste trabalho foi realizado um estudo de remoÃÃo de enxofre a partir de soluÃÃes de benzotiofeno em iso-octano, utilizando os adsorventes SBA-15 e SBA-15/PdCl2. Ãrea superficial BET, volume de poros e diÃmetro de poro dos materiais mesoporos, SBA-15 e SBA-15/PdCl2, foram medidos. A adsorÃÃo do benzotiofeno em iso-octano foi avaliada atravÃs do estudo dinÃmico usando uma coluna de leito fixo em escala de laboratÃrio, utilizando os adsorventes SBA-15 e SBA-15/PdCl2. Para a SBA-15/PdCl2 o estudo de adsorÃÃo em leito fixo foi realizado em quatro temperaturas: 25, 35, 45 e 60ÂC. Curvas de breakthrough foram simuladas de acordo com um modelo matemÃtico que considera as seguintes hipÃteses: operaÃÃo isotÃrmica, fluxo com dispersÃo axial, taxa de fluxo constante, resistÃncia à transferÃncia de massa externa Ãs partÃculas (filme) desprezÃvel, transferÃncia de massa descrita por uma aproximaÃÃo de forÃa motriz linear (LDF), isoterma de adsorÃÃo linear e equilÃbrio de adsorÃÃo atingido instantaneamente na superfÃcie externa das partÃculas adsorventes. Os resultados confirmaram a eficiÃncia da SBA-15/PdCl2 para a utilizaÃÃo em processos de adsorÃÃo de compostos sulfurados. / The demand of a larger control in the emission of pollutants from automobiles, with a reduction in the emission of sulfur, has led to an intense research effort on techniques of sulfur removal from fuels. In the last few years, adsorption is thought to be a suitable polishing technique to achieve a deep desulfurization of streams from hydrodesulfurization (HDS) units. The HDS process is very efficient in the removal of mercaptans and disulfides but higher severity would be required to convert cyclic sulfur molecules, such as tiophenes and benzotiophenes. Due to the bulky size of these refractory sulfur compounds, mesoporous adsorbents are thought to be best suited for adsorption than conventional microporous solids, such as zeolites. The desulfurization by adsorption with modified and selective sorbents is a promising alternative process when compared to the conventional hydrodesulfurization once that process does not need severe conditions of operation which compromise the octane of the gasoline and the final cost of operation. In this present work, a study was coducted to remove sulfur from benzothiophene solutions in isooctante, using the adsorbent SBA-15 and SBA-15/PdCl2. BET surface area, pore volume and pore diameter of SBA-15 and SBA-15/PdCl2 mesoporous materials were measured. Adsorptive desulfurization in benzothiophene/isooctane mixture was carried trough dynamic study using a column of fixed bed in laboratory scale, using sorbents SBA-15 and SBA-15/PdCl2. The adsorption study using SBA-15/PdCl2 was carried on four temperatures: 25, 35, 45 and 60ÂC. Breakthrough curves were simulated according to a mathematical model that assumes the following hypotheses: isothermal operation; flow with axial dispersion; constant fluid flow rate; negligible external film resistance to mass transfer; internal mass transfer described by LDF approximation; linear adsorption isotherm and equilibrium reached instantaneously at the external surface of adsorbent particles. The results confirmed the efficiency of SBA-15/PdCl2 for use in adsorption process of sulfur compounds.