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Synthesis and structure of cage-like mesoporous silica using different precursors

Fantini, Marcia Carvalho de Abreu; Kanagussuko, Cíntia Fabiana; Zilioti, George José Martins; MARTINS, T. S.
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
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In this work the synthesis of cubic, FDU-1 type, ordered mesoporous silica (OMS) was developed from two types of silicon source, tetraethyl orthosilicate (TEOS) and a less expensive compound, sodium silicate (Na(2)Si(3)O(7)), in the presence of a new triblock copolymer template Vorasurf 504 (EO(38)BO(46)EO(38)). For both silicon precursors the synthesis temperature was evaluated. For TEOS the effect of polymer dissolution in methanol and the acid solution (HCl and HBr) on the material structure was analyzed. For Na(2)Si(3)O(7) the influence of the polymer mass and the hydrothermal treatment time were the explored experimental parameters. The samples were examined by Small Angle X-ray Scattering (SAXS) and Nitrogen Sorption. For both precursors the decrease on the synthesis temperature from ambient, -25 degrees C, to -15 degrees C improved the ordered porous structure. For TEOS, the SAXS results showed that there is an optimum amount of hydrophobic methanol that contributed to dissolve the polymer but did not provoke structural disorder. The less electronegative Br-ions, when compared to Cl-, induced a more ordered porous structure, higher surface areas and larger lattice parameters. For Na(2)Si(3)O(7) the increase on the hydrothermal treatment time as well as the use of an optimized amount of polymer promoted a better ordered porous structure. (C) 2011 Elsevier B.V. All rights reserved.

Síntese e caracterização de catalisadores de níquel suportados em sílica mesoporosa altamente ordenada para hidrogenação de óleos vegetais; Synthesis and characterization of highly ordered mesoporous silica supported nickel catalysts for the hydrogenation of vegetable oils

Oliveira, Nara Andréa de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/04/2008 PT
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Este trabalho teve como objetivo a síntese e caracterização de sílicas mesoporosas suportadas com níquel para atuarem como catalisadores na hidrogenação de óleos vegetais. Foram escolhidas as sílicas mesoporosas ordenadas do tipo SBA-15 e FDU-1, sintetizadas a partir de TEOS como fonte de sílica e copolímeros triblocos como agentes direcionadores de estrutura em meio HCl. O Ni(NO3)2.6H2O foi utilizado como fonte de metal, cuja solução aquosa com a concentração de níquel desejada foi adicionada à sílica antes da remoção do molde polimérico, originando os precursores dos catalisadores. Após a impregnação, as amostras foram submetidas à calcinação sob atmosfera de ar, gerando o precursor na forma de óxido que ao ser tratado com H2 é reduzido Nio , forma ativa do catalisador. As técnicas de termogravimetria, termogravimetria derivada, difração de raios X a alto e baixo ângulo, isotermas de adsorção de nitrogênio e absorção atômica foram empregadas para a caracterização destes materiais. A TG/DTG foi utilizada para a simulação das melhores condições de calcinação/redução. As amostras foram calcinadas em um forno tubular com controlador de temperatura. Os ensaios de DRX confirmaram a fase NiO após calcinação e a fase Nio na redução...

Electrochemical study of o-toluidine blue impregnated in mesoporous silica channels

Utrera Martines, Marco Antonio; do Carmo, Devaney Ribeiro; de Castro, Gustavo Rocha; Caetano, Laercio
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 188-193
ENG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); This paper reports an electrochemical study of ordered mesoporous silica impregnated with a cationic dye (o-toluidine blue), prepared with a non-ionic surfactant as the structure-directing agent. O-toluidine blue was chosen because of its utility as an electron transfer mediator (redox catalyst). O-toluidine blue impregnated mesoporous silica was characterized by nitrogen sorption porosimetry, small angle X-ray scattering, infrared spectroscopy, scanning electron microscopy and cyclic voltammetry using chemically modified carbon paste electrodes. Results indicate that the dye is located within the ordered mesopores of micron-sized silica spheres.

Rhodamine 6G encapsuled mesoporous silica channels

Saran, Priscila Samara; Martines, Marco Antonio Utrera; Brito, Hermi Felinto de; Castro, Gustavo Rocha de; Messaddeq, Younes; Ribeiro, Sidney Jose Lima
Fonte: Trans Tech Publications Ltd Publicador: Trans Tech Publications Ltd
Tipo: Conferência ou Objeto de Conferência Formato: 62-67
ENG
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We report the effect of solvent on the rhodamine 6G encapsuled into channels of mesoporous silica, synthesized by two-step process that gives intermediary stable hybrid micelles. Mesoporous materials have been obtained by the method that involves surfactant micelles (mainly cationic) and inorganic precursor of the structure to be obtained. MSU-X type mesoporous silica has been synthesized with polyethylene oxide surfactant as the directing-structure agent and tetraethyl orthosilicate Si(OEt)(4) as the silica source. The influence of the solvent on the encapsulation of rhodamine dye was systematically explored, specially its influence on the luminescence properties. Rhodamine 6G encapsuled into mesoporous silica channel was characterized by UV-Vis and luminescence spectroscopies, scanning electron microscopy, small angle x ray scattering and N(2) sorption-desorption. The pore size and the solvent effects into luminescence dye encapsuled into mesoporous silica channels are observed in the visible absorption and emission spectra of rhodamine 6G. The intense photo luminescence band of rhodamine 6G dye is in 500 to 600 nm region. The observed shift of the absorption and emission bands can be assigned to the effect of the solvents dielectric constant and pore size of mesoporous silica.

On the specific filtration mechanism of a mesoporous silica membrane, prepared with non-connecting parallel pores

Boissière, Cédric; Martines, Marco U.; Larbot, André; Prouzet, Eric
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 17-28
ENG
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We report the singular filtration properties of an ultrafiltration membrane made with mesoporous silica that exhibits cylindrical pores aligned mostly normal to the support. This membrane supported on tubular commercial macroporous alumina supports was prepared by the interfacial growth mechanism between stable silica-surfactant hybrid micelles made of the association of silica oligomers with polyethyleneoxide-based (PEO) surfactants and sodium fluoride, a well-known silica condensation catalyst [Boissière et al., An ultrafiltration membrane made with mesoporous MSU-X silica, Chem. Mater. 15 (2003) 460-463]. It appears that the combined effect of the silica nature of the membrane, whose surface charge can be easily adjusted by changing the pH and the non-connected cylindrical shape of the pores provides a new behavior in the retention properties, as proved by the filtration of polyoxyethylene polymers (PEO) with different molecular weights. Depending on the filtration conditions, a rejection rate of 80% and a steep cut-off at 2000 Da can be obtained or, on the reverse, polymers three times bigger than the pore diameter can diffuse through the membrane. This new filtration mechanism, which opens up new modes of separation modes, is explained in the light of both topology of the porous network and pH-dependent interactions between PEO polymers and silica porous media. © 2004 Elsevier B.V. All rights reserved.

About the thermal stability and pore elimination in the ordered hexagonal mesoporous silica SBA-15

Silveira, T. da; Awano, C. M.; Donatti, D. A.; Vicente, F. S. de; Vollet, D. R.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 227-233
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Ordered hexagonal mesoporous silica was prepared using Pluronic P123 template and removal of the polymer by washing in ethanol. The thermal stability and the pore elimination was studied under heat treatment by a fixed time at 500, 600, 750, 825, 900, and 1050 degrees C. The most part of the porosity is built up by cylindrical pores belonging to the ordered hexagonal 2D pore structure. The lattice parameter and the pore volume of the hexagonal 20 structure diminish regularly with the temperature up to 900 degrees C. All porosity is eliminated at 1050 degrees C. The porosity elimination occurs in a mechanism described by a geometric model of contracting area, in which the diameter of the cylindrical pore diminishes while its length is kept constant. An activation energy of (92 +/- 2) kJ/mol was estimated for the process. The ordered porosity of an ethanol-washed and vacuum dried sample was found to be even larger with a narrower pore size distribution in comparison to a sample directly calcined at 500 degrees C without previous washing in ethanol. (C) 2014 Elsevier Inc. All rights reserved.

Sol-gel thin-film based mesoporous silica and carbon nanotubes for the determination of dopamine, uric acid and paracetamol in urine

Canevari, Thiago C.; Raymundo-Pereira, Paulo A.; Landers, Richard; Benvenutti, Edilson V.; Machado, Sergio A. S.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 726-735
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 11/23047-7; Processo FAPESP: 12/17689-9; This work describes the preparation, characterization and application of a hybrid material composed of disordered mesoporous silica (SiO2) modified with multiwalled carbon nanotubes (MWCNTs), obtained by the sol-gel process using HF as the catalyst. This hybrid material was characterized by N-2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HR-TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This new hybrid material was used for the construction of a thin film on a glassy carbon electrode. The modified electrode using this material was designated SiO2/MWCNT/GCE. The electrocatalytic properties of the electrode toward dopamine, uric acid and paracetamol oxidation were studied by differential pulse voltammetry. Well-defined and separated oxidation peaks were observed in phosphate buffer solution at pH 7.0, in contrast with the ill-defined peaks observed with unmodified glassy carbon electrodes. The electrode had high sensitivity for the determination of dopamine...

Híbridos inorgânico-orgânicos nanoestruturados de sílica mesoporosa e filossilicatos - energética da remoção de cátions na interface sólido/líquido; Nanostructured inorganic-organic hybrids based on mesoporous silica and phyllosilicates - energetics of cations removal at the solid/liquid interface

Syed Badshah
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/02/2011 PT
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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...

Mesoporous silica containing sulfonic acid groups as catalysts for alpha-pinene methoxylation

Castanheiro, J; Guerreiro, L; Fonseca, I; Ramos, A; Vital, J
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
POR
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The methoxylation of a-pinene was studied over sulfonic acid-functionalized mesoporous silica (MCM-41, PMO) at 60ºC. The support functionalization was achieved by the introduction of 3-(mercaptopropyl)trimethoxysilane onto the surface of these materials either by grafting or by co-condensation. The thiol groups were oxidized to SO3H by treatment with H2O2. All the catalysts were active in the studied reaction being the PMO-SO3H-g the best one. Good values of selectivity to a-terpinyl methyl ether were obtained with these catalysts. Catalytic stability of the PMO-SO3H-g was evaluated by performing consecutive batch runs with the same catalyst sample. After the third batch it was observed a stabilisation of the activity.

Adsorption of n-Pentane on Mesoporous Silica and Adsorbent Deformation

Gor, G.Y.; Paris, O.; Prass, J.; Russo, P.A.; Ribeiro Carrott, M.M.L.; Neimark, A.V.
Fonte: ACS Publications Publicador: ACS Publications
Tipo: Artigo de Revista Científica
ENG
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Development of quantitative theory of adsorption-induced deformation is important, e.g., for enhanced coalbed methane recovery by CO2 injection. It is also promising for the interpretation of experimental measurements of elastic properties of porous solids. We study deformation of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs from the shape predicted by thermodynamic theory of adsorption-induced deformation. We show that this difference can be attributed to the difference of disjoining pressure isotherm, responsible for the solid−fluid interactions. We suggest the disjoining pressure isotherm suitable for n-pentane adsorption on silica and derive the parameters for this isotherm from experimental data of n-pentane adsorption on nonporous silica. We use this isotherm in the formalism of macroscopic theory of adsorption-induced deformation of mesoporous materials, thus extending this theory for the case of weak solid−fluid interactions. We employ the extended theory to calculate solvation pressure and strain isotherms for SBA-15 and MCM-41 silica and compare it with experimental data obtained from small-angle X-ray scattering. Theoretical predictions for MCM-41 are in good agreement with the experiment...

Pineapple fruit bromelain recovery using recyclable functionalized ordered mesoporous silica synthesized from sugarcane leaf ash

Arumugam,A.; Ponnusami,V.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 EN
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Bromelain, a protease enzyme found in Ananas comosus (Pineapple), was recovered from the fruit juice by adsorption using recyclable functionalized Santa Barbara Acid-15 (SBA-15) synthesized from sugarcane leaf ash. In this work, highly ordered mesoporous silica was synthesized from sugarcane leaf ash by a template-assisted method. It was successfully used as an adsorbent for the recovery of bromelain from pineapple fruit pulp. Amine-functionalized mesoporous silica exhibited a recovery efficiency of 97.89% and a 6.2-fold purification. It was also established that the adsorbent could be easily regenerated by adjusting the pH. In this study, the adsorbent was reused for three cycles without noticeable loss in recovery efficiency. Thus, adsroption using functionalized SBA-15 appears to be a promising alternate separation technique for the recovery of fruit bromelain.

Synthesis of mesoporous silica microsphere from dual surfactant

Narayanan,Venkatathri
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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A new procedure is reported to synthesis mesoporous silica micro sphere for the first time. In these method two surfactants namely Span 80 and Tween 80 were used. Small angle X ray diffraction and N2 adsorption analysis shows the synthesized material has mesoporous property. The material has spherical morphology with 1-10 µm particle size. Beside the material found to have microcapsule property as observed from the Transmission electron microscopy. The Fourier transform Infrared spectroscopic analysis reveals that the materials are similar to other mesoporous materials. We also encapsulated an UV-absorber Ibuprofen inside the microcapsule, by mixing it before the synthesis. This shows a possibility of the materials in cosmetic applications.

PH-responsive nutraceutical-mesoporous silica nanoconjugates with enhanced colloidal stability

Guillet-Nicolas, R.; Popat, A.; Bridot, J.L.; Monteith, G.; Qiao, S.; Kleitz, F.
Fonte: Wiley-V C H Verlag GMBH Publicador: Wiley-V C H Verlag GMBH
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
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An innovative platform for targeted oral drug delivery is proposed based on the functionalization of drug/dye-loaded mesoporous silica nanoparticles (MSNs) with a biodegradable nutraceutical (β-lactoglobulin). The attachment of the nutraceutical not only protects the drug/dye from leaching in acidic environment, but also effectively allows their release in desired basic sites (pH 7.4).; Rémy Guillet-Nicolas, Amirali Popat, Jean-Luc Bridot, Gregory Monteith, Shi Zhang Qiao, and Freddy Kleitz

Mesoporous silica nanoparticles act as a self-adjuvant for ovalbumin model antigen in mice

Mahony, D.; Cavallaro, A.; Stahr, F.; Mahony, T.; Qiao, S.; Mitter, N.
Fonte: Wiley - VCH Verlag GmbH & Co KGaA Publicador: Wiley - VCH Verlag GmbH & Co KGaA
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
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Immunization to the model protein antigen ovalbumin (OVA) is investigated using MCM-41 mesoporous silica nanoparticles as a novel vaccine delivery vehicle and adjuvant system in mice. The effects of amino surface functionalization and adsorption time on OVA adsorption to nanoparticles are assessed. Amino-functionalized MCM-41 (AM-41) shows an effect on the amount of OVA binding, with 2.5-fold increase in binding capacity (72 mg OVA/g AM-41) compared to nonfunctionalized MCM-41 (29 mg OVA/g MCM-41). Immunization studies in mice with a 10 μg dose of OVA adsorbed to AM-41 elicits both antibody and cell-mediated immune responses following three subcutaneous injections. Immunizations at a lower 2 μg dose of OVA adsorbed to AM-41 particles results in an antibody response but not cell-mediated immunity. The level of antibody responses following immunization with nanoformulations containing either 2 μg or 10 μg of OVA are only slightly lower than that in mice which receive 50 μg OVA adjuvanted with QuilA, a crude mixture of saponins extracted from the bark of the Quillaja saponaria Molina tree. This is a significant result, since it demonstrates that AM-41 nanoparticles are self-adjuvanting and elicit immune responses at reduced antigen doses in vivo compared to a conventional delivery system. Importantly...

MESOPOROUS SILICA MATERIALS IN ASYMMETRIC CATALYSIS AND SELECTIVE FUNCTIONALIZATION

Seki, Tomohiro
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
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This thesis describes the synthesis and application of three types of selectively functionalized mesoporous materials. In the first section, periodically ordered mesoporous organosilicas (PMOs) are prepared that have the axially chiral bidentate phosphine ligand 2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) embedded in the wall structure. Asymmetric hydrogenation of β-ketoesters under high-pressure hydrogen gas and hydrogen transfer reduction were carried out using Ru catalysts resulting from these materials. In the next chapter, our new methodology to selectively functionalize the internal/external surface of SBA-15, a mesoporous silica whose pore diameter is ~8 nm, by blocking the pore surface with reloaded Pluronic P123® micelles is presented. Multiple tests were attempted to validate the efficiency of the methodology including nitrogen adsorption, quantitative analysis by solid state NMRs, fluorescence measurements, elemental analysis and XPS. Eventually SS NMR proved to be the most appropriate. Finally, chapter four describes ordered organic materials in catalysis, namely star-shaped polymers containing chiral core-gels synthesized from chiral 1,1’- binaphthalene-2,2’-diol (BINOL) and 1,1’-binaphthalene-2,2’-diamine (BINAM). The kinetic resolution of 1-phenyl ethanol was carried out expecting to see differential affinity of the chiral core-gel to one enantiomer of the substrate in hydrogen transfer oxidation reaction.; Thesis (Ph.D...

The Chemoselective, Enantiospecific Cross-Coupling of Secondary Boronic Esters and the Stability of Mesoporous Silica Supports for Pd Catalysis

GLASSPOOLE, BEN WILLIAM
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
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The Suzuki-Miyaura Cross-Coupling of aryl halides and aryl boronic esters has become one of the most important and oft used C-C bond forming reactions in industry and academia alike. Recently, substantial effort has been invested in expanding this reaction to include alkyl boronic esters as coupling partners, though until recently, success has been limited to primary alkyl boronic esters. Secondary alkyl boronic esters, with the inherent possibility of being chiral, have proven to be more difficult to couple. As a means of expanding our program on the enantio- and regioselective hydroboration of styrene derivatives, we sought to develop conditions that could couple benzylic (secondary) boronic esters. Not only was the coupling to aryl iodides achieved in moderate to good yield with a commercially available (and relatively cheap) catalyst system and phosphine, but the coupling reaction proceeds with almost complete retention of the stereochemistry installed during the hydroboration reaction. Interestingly, these conditions leave primary (linear) alkyl boronic esters completely untouched. Further examination of the chemoselectivity of the reaction revealed that, despite being unable to cross-couple strictly aliphatic secondary boronic esters...

Surfactant-templated mesoporous silica as a pigment in inkjet paper coatings

Wedin, Par; Svanholm, E; Alberius, P C A; Fogden, Andrew
Fonte: Pulp and Technical Association of Canada Publicador: Pulp and Technical Association of Canada
Tipo: Artigo de Revista Científica
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The feasibility of a novel type of surfactant-templated mesoporous silica particles as pigments in Inkjet paper has been evaluated. The surfactant-templated mesoporous silica pigments with small pores and narrow pore-size distribution were investigated, a

Surfactant-templated mesoporous silica as a pigment in inkjet paper coatings

Wedin, Par; Svanholm, E; Alberius, P C A; Fogden, A
Fonte: Pulp and Technical Association of Canada Publicador: Pulp and Technical Association of Canada
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
69.00568%
The feasibility of a novel type of surfactant-templated mesoporous silica particles as pigments in Inkjet paper has been evaluated. The surfactant-templated mesoporous silica pigments with small pores and narrow pore-size distribution were investigated, a

Phase behavior and preparation of mesoporous silica in aqueous mixtures of fluorinated surfactant and hydrophobic fluorinated polymer

Sharma, Suraj Chandra; Kunieda, Hironobu; Esquena, Jordi; Rodríguez Abreu, Carlos
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 19968 bytes; application/msword
ENG
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8 pages, 10 figures.; The phase behavior and formation of self-assemblies in the ternary water/fluorinated surfactant (C8F17EO10)/hydrophobic fluorinated polymer (C3F6O)nCOOH system and the application of those assemblies in the preparation of mesostructured silica have been investigated by means of phase study, small angle X-ray scattering, and rheology. Hexagonal (H1), bicontinuous cubic (V1) with Ia3d symmetry, and polymer rich lamellar () are observed in the ternary diagram. C8F17EO10 molecules are dissolved in polymer rich aggregates, whereas (C3F6O)nCOOH molecules are practically insoluble in the surfactant lamellar phase due to packing restrictions. Hence, two types of lamellar phases exist: one with surfactant rich (Lα) and the other with polymer rich () in the water/C8F17EO10/(C3F6O)nCOOH system. As suggested by rheological measurements, worm-like micelles are present in C8F17EO10 aqueous solutions but a rod-sphere transition takes place by solubilization of (C3F6O)nCOOH. C8F17EO10 acts as a structure directing agent for the preparation of hexagonal mesoporous silica by the precipitation method. The addition of (C3F6O)nCOOH induces the formation of larger but disordered pores.; We dedicate this paper to the memory of our dear Prof. Hironobu Kunieda who recently passed away. This work was supported by CREST of JST (Japan Science and Technology Corporation). C.R. is grateful to the Japan Society for the Promotion of Science (JSPS) for a research grant. We acknowledge Prof. J. Tatami and Dr. T. Wakihara of Yokohama National University for their help in the adsorption measurements...

Hydrothermal Synthesis of Mesoporous Silica MCM-41 Using Commercial Sodium Silicate

Meléndez-Ortiz,Héctor Iván; Mercado-Silva,Alfonso; García-Cerda,Luis Alfonso; Castruita,Griselda; Perera-Mercado,Yibran Argenis
Fonte: Sociedad Química de México A.C. Publicador: Sociedad Química de México A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
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In this work, ordered mesoporous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na2SiO3) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as pH regulator. The influence of CTAB/SiO2 molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption isotherms. Ordered mesoporous MCM-41 silica was obtained at 80 °C by using a range of CTAB/SiO2 molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-PrOH) as co-surfactant.