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Síntese de carbonos cerâmicos mesoporosos para aplicação como eletrodos em células a combustível a metanol direto; Synthesis of the novel mesoporous carbon ceramics for application on direct fuel cell electrodes

Jean Marcel Ribeiro Gallo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/03/2010 PT
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Esse trabalho teve como objetivo a aplicação de peneiras moleculares mesoporosas de sílica como suporte para metal em aplicações em eletrodos na Célula a combustível a metanol direto (DMFC). As peneiras moleculares mais importantes, MCM-41, MCM-48 e SBA-15, foram escolhidas. Em um primeiro momento a reprodutibilidade das sínteses foi verificada. Como pesquisa lateral foi estudada a acidez de superfície da SBA-15 contendo alumínio obtida por síntese direta. Além disso, foi desenvolvida a primeira síntese direta para a [Al]-SBA-15 Sílica é um isolante elétrico e, portanto, não pode ser utilizada como um eletrodo, deste modo, uma nova família de compósitos chamada Carbonos Cerâmicos Mesoporosos (MCC) foi preparada pela adição de grafite comercial na síntese das sílicas mesoporosas (MCM-41, MCM-48 ou SBA-15). A grafite não influenciou na formação da mesofase de sílica, de qualquer maneira, a MCC-MCM-41 e a MCC-MCM-48 cresceram na superfície da grafite. As MCCs preparadas com razão em massa sílica/carbono de 1/1 e 1/1.25 apresentaram condutividades elétricas similares enquanto MCCs com menos quantidade de carbono se mostraram isolantes elétricos. As MCCs(1/1) modificadas com 20 % em massa de paládio foram usadas na DMFC chegando no máximo a desempenhos 10 vezes menores que o do sistema usando o suporte comercia Vulcan XC-72R. Esse comportamento foi atribuida a menos condutividade elétrica dos MCCs. Para aumentar a condutividade elétrica dos MCCs(1/1)...

Direct synthesis without addition of acid of Al-SBA-15 with controllable porosity and high hydrothermal stability

Lin, S.; Shi, L.; Ribeiro Carrott, M.M.L.; Carrott, P.J.M.; Rocha, J.; Li, M.R.; Zou, X.D.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
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Using triblock copolymer Pluronic P123 as a structure-directing agent, water as solvent, tetraethyl orthosilicate (TEOS) and aluminium sulfate (Al2(SO4)3 18H2O) as silica and aluminium sources, respectively, a series of Al-SBA-15 with well-ordered mesostructure has been hydrothermally synthesized up to high aging temperature through a one-step approach in an environmentally friendly mineral acid-free medium. The influence of some synthesis parameters such as Si/Al molar ratio (5–100), P123/Si molar ratio (0.0025–0.014) and aging temperature (363–443 K) on the properties of the resultant materials were investigated by powder X-ray diffraction (XRD), nitrogen adsorption–desorption at 77 K, transmission electron microscopy (TEM), and solid state 27Al MAS NMR analyses. The textural properties of Al-SBA-15, such as specific surface area, pore volume and mesopore size, can be modified by simply adjusting those synthesis parameters. Solid state 27Al MAS NMR results show direct evidence that aluminium is introduced onto the wall structure and located mainly at tetrahedrally coordinated sites. The structural ordering increases with increasing aluminium sulfate amount in the gel from Si/Al of 100–5, with the aluminium species playing an important role in the formation of the ordered mesostructure. The increase of aging temperature causes widening of mesopores...

ADSORÇÃO DE NAPROXENO, NORFLOXACINA E RODAMINAS EM MATERIAIS MESOPOROSOS ORDENADOS

Galacho, Cristina; Carrott, Manuela; Carvalhal, Cristina; Caixinha, Nadia; Russo, Patrícia; Carrot, Perer
Fonte: XXXV Reunião Ibérica de Adsorção Publicador: XXXV Reunião Ibérica de Adsorção
Tipo: Artigo de Revista Científica
POR
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O presente trabalho foca o estudo da influência das propriedades texturais e químicas de materiais mesoporosos, assim como, das condições operacionais do meio, nomeadamente, temperatura e pH, no processo de adsorção / imobilização de alguns compostos das classes referidas. O trabalho envolve a preparação, funcionalização e caracterização de materiais mesoporosos ordenados (incluindo do tipo MCM-41 e SBA-15) e estudos cinéticos e de equilíbrio de adsorção / imobilização de fármacos e de compostos luminescentes com dimensão molecular considerável, como por exemplo, o naproxeno (anti-inflamatório não esteroíde), a norfloxacina (antibiótico) e as rodaminas B e 6G (corantes orgânicos da família das fluoronas).

Antibody Specificities and Effect of Meningococcal Carriage in Icelandic Teenagers Receiving the Norwegian Serogroup B Outer Membrane Vesicle Vaccine

Wedege, Elisabeth; Kuipers, Betsy; Bolstad, Karin; van Dijken, Harry; Frøholm, L. Oddvar; Vermont, Clementien; Caugant, Dominique A.; van den Dobbelsteen, Germie
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2003 EN
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18.825186%
Antibody specificities of pre- and postvaccination serum samples from 40 (53%) teenagers who received three doses of the Norwegian Neisseria meningitidis serogroup B vaccine (B:15:P1.7,16) during a previous trial in Iceland (Perkins et al., J. Infect. Dis. 177:683-691, 1998) were analyzed with serum bactericidal activity (SBA) and immunoblotting assays with reference and isogenic meningococcal H44/76 vaccine strains. The H44/76 variants demonstrated significant vaccine-induced SBA to P1.7,16 PorA and Opc but not to PorB, Opa5.5, and a heterologous PorA protein. On blots, immunoglobulin G levels to all these proteins increased significantly after vaccination. Measurement of SBA to the two main variable regions (P1.7 and P1.16) on the P1.7,16 PorA with PorA deletion mutants revealed significantly higher activity to the P1.7,− and P1.−,16 mutants compared to the P1.7,16 strain, indicating exposure of new accessible epitopes. Only 12 (30%) serum samples showed distinct decreases with these or the P1.−,− mutant, with most samples containing SBA to the P1.7 and P1.16 combination. In contrast, P1.16-specific antibodies were mainly found on blots. Thirteen of the vaccinees (32.5%) were carriers of meningococci at the time of the third dose...

Protection by Natural Human Immunoglobulin M Antibody to Meningococcal Serogroup B Capsular Polysaccharide in the Infant Rat Protection Assay Is Independent of Complement-Mediated Bacterial Lysis

Toropainen, Maija; Saarinen, Leena; Wedege, Elisabeth; Bolstad, Karin; Michaelsen, Terje E.; Aase, Audun; Käyhty, Helena
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2005 EN
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Neisseria meningitidis, an important cause of bacterial meningitis and septicemia worldwide, is associated with high mortality and serious sequelae. Natural immunity against meningococcal disease develops with age, but the specificity and functional activity of natural antibodies associated with protection are poorly understood. We addressed this question by using a selected subset of prevaccination sera (n = 26) with convergent or discrepant serum bactericidal activity (SBA) and infant rat protective activity (IRPA) against the serogroup B meningococcal strain 44/76-SL (B:15:P1.7,16) from Icelandic teenagers (B. A. Perkins et al., J. Infect. Dis. 177:683-691, 1998). The sera were analyzed by opsonophagocytic activity (OPA) assay, immunoblotting, immunoglobulin G (IgG) quantitation against live meningococcal cells by flow cytometry, and enzyme immunosorbent assay (EIA). High levels of SBA and OPA were reflected in distinct IgG binding to major outer membrane proteins and/or lipopolysaccharide in immunoblots. However, we could not detect any specific antibody patterns on blots that could explain IRPA. Only IgM antibody to group B capsular polysaccharide (B-PS), measured by EIA, correlated positively (r = 0.76, P < 0.001) with IRPA. Normal human sera (NHS; n = 20) from healthy Finnish children of different ages (7...

Kinetics of Antibody Persistence following Administration of a Combination Meningococcal Serogroup C and Haemophilus influenzae Type b Conjugate Vaccine in Healthy Infants in the United Kingdom Primed with a Monovalent Meningococcal Serogroup C Vaccine ▿

Borrow, Ray; Andrews, Nick; Findlow, Helen; Waight, Pauline; Southern, Joanna; Crowley-Luke, Annette; Stapley, Lorraine; England, Anna; Findlow, Jamie; Miller, Elizabeth
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
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The kinetics of antibody persistence following the administration of a combination meningococcal serogroup C and Haemophilus influenzae type b (Hib) conjugate vaccine (Menitorix) in the second year of life in children primed with two doses of one of three monovalent meningococcal serogroup C (MCC) vaccines was investigated. The study subjects were administered either Menitorix at 12 to 15 months of age, followed by the seven-valent pneumococcal conjugate vaccine (PCV7) and the measles, mumps, and rubella vaccine 4 to 6 weeks later, or all three vaccines concomitantly at 12 to 15 months of age. Blood samples were collected before and 1, 2, 12, and 24 months after the boosting. Sera were analyzed for meningococcal serogroup C serum bactericidal antibody (SBA) and IgG as well as Hib-polyribosylribitol phosphate (PRP)-specific IgG. The antibody persistence data from this study were compared to those of a prior study of Southern et al. (Clin. Vaccine Immunol. 14:1328-1333, 2007) in which children were given three primary doses of a vaccine containing both the MCC and the Hib vaccines but were boosted only with a Hib conjugate vaccine. The magnitude of the meningococcal SBA geometric mean titer was higher for those subjects primed with the MCC vaccine conjugated to tetanus toxoid (NeisVac-C) than for those primed with one of two MCC vaccines conjugated to CRM197 (Menjugate or Meningitec) up to 1 year following boosting. Two years after boosting...

Infuence of Microstructure in Drug Release Behavior of Silica Nanocapsules

Gonzalez, Gema; Sagarzazu, Amaya; Zoltan, Tamara
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
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27.317896%
Meso- and nanoporous structures are adequate matrices for controlled drug delivery systems, due to their large surface areas and to their bioactive and biocompatibility properties. Mesoporous materials of type SBA-15, synthesized under different pH conditions, and zeolite beta were studied in order to compare the different intrinsic morphological characteristics as pore size, pore connectivity, and pore geometry on the drug loading and release process. These materials were characterized by X-ray diffraction, nitrogen adsorption, scanning and transmission electron microscopy, and calorimetric measurements. Ibuprofen (IBU) was chosen as a model drug for the formulation of controlled-release dosage forms; it was impregnated into these two types of materials by a soaking procedure during different periods. Drug loading and release studies were followed by UV-Vis spectrophotometry. All nano- and mesostructured materials showed a similar loading behavior. It was found that the pore size and Al content strongly influenced the release process. These results suggest that the framework structure and architecture affect the drug adsorption and release properties of these materials. Both materials offer a good potential for a controlled delivery system of ibuprofen.

Pyrolysis and co-pyrolysis of Laminaria japonica and polypropylene over mesoporous Al-SBA-15 catalyst

Lee, Hyung Won; Choi, Suek Joo; Park, Sung Hoon; Jeon, Jong-Ki; Jung, Sang-Chul; Kim, Sang Chai; Park, Young-Kwon
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 01/08/2014 EN
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The catalytic co-pyrolysis of a seaweed biomass, Laminaria japonica, and a typical polymer material, polypropylene, was studied for the first time. A mesoporous material Al-SBA-15 was used as a catalyst. Pyrolysis experiments were conducted using a fixed-bed reactor and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). BET surface area, N2 adsorption-desorption isotherms, and NH3 temperature programmed desorption were measured to examine the catalyst characteristics. When only L. japonica was pyrolyzed, catalytic reforming slightly increased the gas yield and decreased the oil yield. The H2O content in bio-oil was increased by catalytic reforming from 42.03 to 50.32 wt% due to the dehydration reaction occurring on the acid sites inside the large pores of Al-SBA-15. Acids, oxygenates, mono-aromatics, poly aromatic hydrocarbons, and phenolics were the main components of the bio-oil obtained from the pyrolysis of L. japonica. Upon catalytic reforming over Al-SBA-15, the main oxygenate species 1,4-anhydro-d-galactitol and 1,5-anhydro-d-manitol were completely removed. When L. japonica was co-pyrolyzed with polypropylene, the H2O content in bio-oil was decreased dramatically (8.93 wt% in the case of catalytic co-pyrolysis), contributing to the improvement of the oil quality. A huge increase in the content of gasoline-range and diesel-range hydrocarbons in bio-oil was the most remarkable change that resulted from the co-pyrolysis with polypropylene...

Nanoporous composites prepared by a combination of SBA-15 with Mg–Al mixed oxides. Water vapor sorption properties

Pérez-Verdejo, Amaury; Sampieri, Alvaro; Pfeiffer, Heriberto; Ruiz-Reyes, Mayra; Santamaría, Juana-Deisy; Fetter, Geolar
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 07/08/2014 EN
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This work presents two easy ways for preparing nanostructured mesoporous composites by interconnecting and combining SBA-15 with mixed oxides derived from a calcined Mg–Al hydrotalcite. Two different Mg–Al hydrotalcite addition procedures were implemented, either after or during the SBA-15 synthesis (in situ method). The first procedure, i.e., the post-synthesis method, produces a composite material with Mg–Al mixed oxides homogeneously dispersed on the SBA-15 nanoporous surface. The resulting composites present textural properties similar to the SBA-15. On the other hand, with the second procedure (in situ method), Mg and Al mixed oxides occur on the porous composite, which displays a cauliflower morphology. This is an important microporosity contribution and micro and mesoporous surfaces coexist in almost the same proportion. Furthermore, the nanostructured mesoporous composites present an extraordinary water vapor sorption capacity. Such composites might be utilized as as acid-base catalysts, adsorbents, sensors or storage nanomaterials.

Degradacao termica e catalitica da borra oleosa de Petroleo com materiais nanoestruturados al-mcm-41 e AL-SBA-15

Paulino, Ana Adalgisa Dias
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia do Petróleo; Pesquisa e Desenvolvimento em Ciência e Engenharia de Petróleo Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia do Petróleo; Pesquisa e Desenvolvimento em Ciência e Engenharia de Petróleo
Tipo: Tese de Doutorado Formato: application/pdf
POR
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99.21936%
Aiming to reduce and reuse waste oil from oily sludge generated in large volumes by the oil industry, types of nanostructured materials Al-MCM-41 and Al-SBA-15, with ratios of Si / Al = 50, were synthesized , and calcined solids used as catalysts in the degradation of oily sludge thermocatalytic oil from oilfield Canto do Amaro, in the state of Rio Grande do Norte. Samples of nanostructured materials were characterized by thermogravimetric analysis (TG / DTG), X-ray diffraction (XRD), scanning electron microscopy (SEM), absorption spectroscopy in the infrared Fourier transform (FT-IR) and adsorption nitrogen (BET). The characterization showed that the synthesized materials resulted in a catalyst nanostructure, and ordered pore diameter and surface area according to existing literature. The oily sludge sample was characterized by determining the API gravity and sulfur content and SARA analysis (saturates, aromatics, resins and asphaltenes). The results showed a material equivalent to the average oil with API gravity of 26.1, a low sulfur content and considerable amount of resins and asphaltenes, presented above in the literature. The thermal and catalytic degradation of the oily sludge oil was performed from room temperature to 870 ° C in the ratios of heating of 5...

Degradação térmica e catalítica do resíduo atmosférico de petróleo (RAT), utilizando materiais nanoestruturados do tipo SBA-15

Castro, Kesia Kelly Vieira de
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Química; Físico-Química; Química Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Química; Físico-Química; Química
Tipo: Tese de Doutorado Formato: application/pdf
POR
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In this work were synthesized and characterized the materials mesoporous SBA-15 and Al- SBA-15, Si / Al = 25, 50 and 75, discovered by researchers at the University of California- Santa Barbara, USA, with pore diameters ranging from 2 to 30 nm and wall thickness from 3.1 to 6.4 nm, making these promising materials in the field of catalysis, particularly for petroleum refining (catalytic cracking), as their mesopores facilitate access of the molecules constituting the oil to active sites, thereby increasing the production of hydrocarbons in the range of light and medium. To verify that the materials used as catalysts were successfully synthesized, they were characterized using techniques of X-ray diffraction (XRD), absorption spectroscopy in the infrared Fourier transform (FT-IR) and adsorption nitrogen (BET). Aiming to check the catalytic activity thereof, a sample of atmospheric residue oil (ATR) from the pole Guamaré-RN was performed the process by means of thermogravimetry and thermal degradation of catalytic residue. Upon the curves, it was observed a reduction in the onset temperature of the decomposition process of catalytic ATR. For the kinetic model proposed by Flynn-Wall yielded some parameters to determine the apparent activation energy of decomposition...

Preparació d'òxids mesoporosos mitjançant nanocasting

Cabo Sanz, Moisés; Pellicer Vilà, Eva M.; Rossinyol Casals, Emma
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
Publicado em //2008 CAT
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S’ha sintetitzat pel mètode de nanocasting pols nanomètrica d’In2O3, NiO i Co3O4 utilitzant diferents mesoestructures de sílice (SBA-16, SBA-15 i KIT-6) com a motlle rígid. Les rèpliques obtingudes s’han caracteritzat amb les tècniques de difracció de raigs X, microscòpia electrònica de rastreig, microscòpia electrònica de transmissió d’alta resolució i BET. L’òxid d’indi, l’òxid de níquel i l’òxid de cobalt obtinguts a partir de la sílice SBA-15 i KIT-6 conserven perfectament l’estructura mesopòrica del motlle, amb valors del diàmetre de porus al voltant dels 7-8 nm. Les rèpliques del motlle SBA-15 estan formades per nanofilaments llargs, mentre que les rèpliques de KIT-6 presenten una estructura hexagonal. A partir del motlle de tipus gàbia (SBA-16), si bé el Co3O4 obtingut és mesopòric, en els altres dos casos (In2O3 i NiO) no s’ha observat ordenament. Per a les rèpliques In2O3 KIT-6 i NiO SBA-15, la caracterització mitjançant BET ha permès corroborar el caràcter mesoestructurat de les mostres.; In2O3, NiO and Co3O4 nanopowders were synthesized by the nanocasting method using different silica mesostructures (SBA-16, SBA-15 and KIT-6) as hard templates. The replicas were characterized by X-ray powder diffraction...

ADSORCIÓN DE METIL METACRILATO EN SÍLICES MESOPOROSAS TIPO SBA-15 Y SBA-16 Y PREPARACIÓN DEL HÍBRIDO PMMA/SBA-16

GÓMEZ,LORENA; PABÓN GÉLVES,ELIZABETH; LÓPEZ,BETTY LUCY; RAMÍREZ VÉLEZ,ALEJANDRO
Fonte: DYNA Publicador: DYNA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 ES
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En este trabajo se reporta la síntesis del material híbrido polimetilmetacrilato (PMMA)/sílice mesoporosa SBA-16. El monómero metacrílico es adsorbido por la sílice y posteriormente polimerizado mediante tratamiento térmico, empleando como iniciador peróxido de benzoilo. El porcentaje en peso adsorbido es determinado empleando espectroscopia ultravioleta y su conversión a PMMA es seguida mediante espectroscopia infrarroja con transformada de Fourier. La disminución en el área superficial y en los diámetros de poro, además de la ausencia de una temperatura de transición vítrea, confirman que las macromoléculas se encuentran ocluidas en los canales del sólido. La inserción del polímero al interior de la estructura mesoporosa, origina una red orgánica-inorgánica interpenetrada, convirtiendo a este compuesto molecular en un potencial agente reforzante para matrices poliméricas basadas en metacrilatos.

Transformación de n-pentano sobre catalizadores de platino soportado en tamices moleculares mesoporosos SBA-15 con aluminio

López,Carmen M; Ortiz,Carolina; Sazo,Virginia; García,Luis
Fonte: Universidad Central de Venezuela Publicador: Universidad Central de Venezuela
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 ES
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48.00948%
Se realizó la transformación de n-pentano en condiciones de hidroisomerización bajo corriente de H2 a 300ºC y deshidroisomerización a 500ºC bajo un flujo H2:N2. Los catalizadores usados en este estudio consisten de Pt soportado en tamices moleculares mesoporosos tipo SBA-15, con aluminio incorporado mediante síntesis directa y por impregnación de los soportes silícicos. La incorporación de Al resultó exitosa por ambos métodos, produciendo sólidos con actividad catalítica para la transformación de n-pentano en las condiciones evaluadas. En la deshidroisomerización, la incorporación de Pt produjo un aumento notable de la selectividad a pentenos, mientras que en la hidroisomerización mostró un papel determinante en la conversión lograda, con alta selectividad a iso-pentano en el catalizador soportado sobre el sólido impregnado con aluminio.