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Transition metal (Cu, Cr, and V) modified MCM-41 for the catalytic wet air oxidation of aniline

Gomes, Helder; Selvam, Parasuraman; Dapurkar, Sudhir; Figueiredo, José; Faria, Joaquim
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG; ENG
Relevância na Pesquisa
68.540176%
Mesoporous MCM-41 based materials containing various transition metals (Cr, Cu and V) were prepared hydrothermally and characterized using various analytical and spectroscopic techniques. Cr and Cu are randomly anchored to the surface of MCM-41 support, while V is predominantly present as penta-valent species within the framework structure of the support. The catalytic activity was tested in the wet air oxidation of aniline aqueous solutions (2 g/L) using a high-pressure reactor at 200 C with an oxygen partial pressure of 6.9 bar. Among the prepared materials, (Cu)MCM-41 showed a significant catalytic activity with an aniline conversion after 2 h of 96% and a selectivity towards CO2 formation of 76%. Although some leaching of the Cu was observed, the catalyst showed a good performance and stability after re-use in at least three consecutive cycles.

Catalytic wet air oxidation of aniline on transition metal modified MCM-41 catalysts

Gomes, Helder; Selvam, Parasuraman; Dapurkar, Sudhir; Figueiredo, José; Faria, Joaquim
Fonte: [s.n.] Publicador: [s.n.]
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
68.540176%
Transition metal (Cu, Cr and V) MCM-41 catalysts were prepared hydrothermally and characterized by X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray (SEM/EDX), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and N2 adsorption-desorption analysis at -196ºC. The catalysts were tested in the catalytic wet air oxidation (CWAO) of aniline aqueous solutions at 200ºC and 6.9 bar of oxygen partial pressure. The (Cu)MCM-41 catalyst showed the best performance with respect to combined activity and selectivity for aniline conversion to nonorganic compounds. After 2 h of reaction, 96% aniline conversion and 76% of selectivity were attained. Under the employed reaction conditions, leaching of copper was detected in small extent. However, heterogeneous catalytic activity was proved and attributed to copper oxide anchored to MCM-41.

Zinc(II) phthalocyanines immobilized in mesoporous silica Al-MCM-41 and their applications in photocatalytic degradation of pesticides

Silva, M.; Calvete, M. J. F.; Gonçalves, N. P. F.; Burrows, H. D.; Sarakha, M.; Fernandes, A.; Ribeiro, M. F.; Azenha, M. E; Pereira, M. M.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
68.658184%
In the present study the authors investigated a set of three new zinc(II) phthalocyanines (zinc(II) tetranitrophthalocyanine (ZnTNPc), zinc(II) tetra(phenyloxy)phthalocyanine (ZnTPhOPc) and the tetraiodide salt of zinc(II)tetra(N,N,N-trimethylaminoethyloxy) phthalocyaninate (ZnTTMAEOPcI)) immobilized into Al-MCM-41 prepared via ship-in-a-bottle methodology. The samples were fully characterized by diffuse reflectance-UV–vis spectroscopy (DRS-UV–vis), luminescence, thermogravimetric analysis (TG/DSC), N2 adsorption techniques and elemental analysis. A comparative study was made on the photocatalytic performance upon irradiation within the wavelength range 320–460 nm of these three systems in the degradation of pesticides fenamiphos and pentachlorophenol. ZnTNPc@Al-MCM-41 and ZnTTMAEOPcI@Al-MCM-41 were found to be the most active systems, with the best performance observed with the immobilized cationic phthalocyanine, ZnTTMAEOPcI@Al-MCM-41. This system showed high activity even after three photocatalytic cycles. LC–MS product characterization and mechanistic studies indicate that singlet oxygen (1O2), produced by excitation of these immobilized photosensitizers, is a key intermediate in the photocatalytic degradation of both pesticides.

Preparation of different basic Si-MCM-41 catalysts and application in the Knoevenagel and Claisen-Schmidt condensation reactions

Martins, Leandro; Hoelderich, Wolfgang; Hammer, Peter; Cardoso, Dilson
Fonte: Academic Press Inc. Elsevier B.V. Publicador: Academic Press Inc. Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 220-227
ENG
Relevância na Pesquisa
68.87337%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); In the present work, the basicity of three different Si-MCM-41 mesoporous materials, namely, (1) as-synthesized Si-MCM-41, (2) Si-MCM-41 modified by dispersing cesium oxide (Cs(2)O) and (3) Si-MCM-41 with anchored aminopropylsilyl group was compared for the first time. The fact that Knoevenagel and Claisen-Schmidt condensations stand out to be important in carbon-carbon bond formation as well as in the preparation of fine chemicals and intermediates, led them to be used as model reactions for the purpose of evaluating the catalytic performance. The activity of the modified samples was compared with that of the as-synthesized material [CTA(+)]-Si-MCM-41 (where CTA(+) stands for the structure directing agent). This catalyst presented the highest catalytic activity compared to that of Si-MCM-41 modified with Cs(2)O or aminopropylsilyl group. This is of extreme high advantage, because it can be used as-synthesized without further modification. Furthermore, structural properties of the Si-MCM-41 samples were determined based on X-ray diffraction measurements (XRD), nitrogen adsorption/desorption isotherms, (29)Si nuclear magnetic resonance (MAS NMR) and X-ray photoelectron spectroscopy (XPS). (C) 2010 Elsevier B.V. All rights reserved.

Effect of the catalyst MCM-41 on the kinetic of the thermal decomposition of poly(ethylene terephthalate)

Araujo, Sulene A.; Araujo, Antonio S.; Fernandes, Nedja S.; Fernandes, Valter J.; Ionashiro, Massao
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 465-469
ENG
Relevância na Pesquisa
68.658184%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); The aim of this work is to determine the activation energy for the thermal decomposition of poly (ethylene terephthalate)-PET, in the presence of a MCM-41 mesoporous catalyst. This material was synthesized by the hydrothermal method, using cetyltrimethylammonium as template. The PET sample has been submitted to thermal degradation alone and in presence of MCM-41 catalyst at a concentration of 25% in mass (MCM-41/PET). The degradation process was evaluated by thermogravimetry, at temperature range from 350 to 500 degrees C, under nitrogen atmosphere, with heating rates of 5, 10 and 25 degrees C min(-1). From TG, the activation energy, determined using the Flynn-Wall kinetic method, decreased from 231 kJ mol(-1), for the pure polymer (PET), to 195 kJ mol(-1), in the presence of the material (MCM-41/PET), showing the catalyst efficiency for the polymer decomposition process.

Sintese e caracterização de [Nb]-MCM-41 e NbxOy(OH)z-montmorilonita e aplicações em catalise redox e acida; Synthesis and characterization of [Nb]-MCM-41 and NbxOy(OH)z-montmorillonite and its applications in redox and acid catalysis

Jean Marcel Ribeiro Gallo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/09/2005 PT
Relevância na Pesquisa
68.91948%
Otimizamos a síntese da Nb-MCM-41 à temperatura ambiente, variando a base, as fontes de sílica e nióbio e a ordem de adição da fonte de nióbio. Os materiais, antes e após a calcínação, foram caracterizados por difração de raios-X e reflectância difusa na região do UV-Vis. A Nb-MCM-41 com o melhor resultado foi silanizada e caracterizada por espectroscopia de emissão atômica por plasma indutivamente acoplado (ICP-OES), análise termogravimétrica (TGA), adsorção-dessorção de nitrogênio, ressonância magnética nuclear no ângulo mágico (RMN-MAS) de Si, análise elementar de carbono, hidrogênio e nitrogênio (CHN) e espectroscopia na região do infravermelho (IV). As Nb-MCM-41 calcinada e a silanizada foram testadas na epoxidação de cis-cicloocteno com terc-butilhidroperóxido (TBHP) 69,4 % em cicloexano obtendo após 48 h, 46,6 e 62,2 % de conversão e 77 e 94 % de seletividade, respectivamente. Usando peróxido de hidrogênio 70 % em água obtivemos após 5 h, 8 % de conversão e 80% de seletividade para a amostra calcinada e 13 % de conversão e 70 % de seletividade para a silanizada. Nas reações usando peróxido de hidrogênio aquoso. este foi todo consumido nas 10 primeiras horas. mostrando que o nióbio decompõe facilmente o peróxido de hidrogênio. Montmorilonita K-10 foi trocada com polihidroxi-nióbio e caracterizada por difração de raios-X...

Síntese e caracterização de MCM-41 impregnada com bário e cromo e suas propriedades catalíticas para reações de convensão de etanol; Synthesis and characterization of MCM-41 impregnated with barium and chromium and their catalytic properties for ethanol conversion reactions

Nathália La Salvia
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 02/07/2010 PT
Relevância na Pesquisa
69.043257%
Peneiras moleculares do tipo MCM-41 foram sintetizadas e impregnadas com 16% de bário e 1,4%; 2,9% e 5,6 % de cromo. As amostras foram então calcinadas e caracterizadas, e utilizadas na conversão catalítica de etanol. Esses materiais apresentaram áreas superficiais entre 400 a 1.200 m2 g-1. Os difratogramas de raios X mostraram que fases da MCM-41 foram obtidas. A introdução de Ba e Cr resultou em picos de DRX diferentes da MCM-41, sugerindo a formação de fases cristalinas diferentes dentro da peneira molecular. O aumento da quantidade do Cr (1,4; 2,9 e 5,6%) provoca um aumento na intensidade cristalina. Os testes catalíticos foram realizados em um reator de leito fixo, as temperaturas de reação utilizadas foram 600, 650, 700 e 750 K e as pressões de etanol de 5820, 4278, 3110 e 2220 Pa, a massa utilizada foi 30 mg, e o fluxo de etanol de 2×10-6 m3 s-1. Os produtos da reação identificados por um cromatógrafo a gás com uma coluna Porapak Q foram o eteno, etoxietano, acetaldeído, água e butadieno e suas concentrações foram calculadas com base na área do pico e os fatores de resposta térmicos. Os cálculos dos efeitos difusivos demonstraram que a transferência de massa externa para reações a 750 K podem ser limitantes da reação. Foram realizados também os cálculos da taxa de reação...

Estudo das reações de etanol catalisadas com MCM-41 impregnada com molibdênio e magnésio; Study of ethanol reactions catalyzed with impregnate molybdenum and magnesium in MCM-41

Pablo Miguel Coha Vesga
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/07/2013 PT
Relevância na Pesquisa
68.747407%
Reações de desidrogenação e desidratação no etanol são de grande interesse, já que levam à produção de compostos que são utilizados na indústria química, farmacêutica e cosmética. No presente trabalho, catalisadores de magnésio e molibdênio suportados na peneira molecular MCM-41 foram utilizados no estudo das reações de desidrogenação e desidratação de etanol. Os catalisadores foram preparados através da impregnação por umidade incipiente de nitrato de magnésio e heptamolibdato de amônia, com teores de 0,5% a 2,0% em massa para o magnésio e de 3,0% para o molibdênio. O Mg após a impregnação se apresentou como óxido de Mg e o Mo como óxido de Mo ou carbeto de Mo. Os materiais foram secados, calcinados e caracterizados através de Microscopia Eletrônica de Varredura (MEV), Energia Dispersiva de Raios-X (EDS), Difração de Raios X (DRX), Adsorção Física de Nitrogênio, Análise Infravermelho, Análise Termogravimétrica (TGA). Depois de calcinados, os catalisadores foram carregados no reator, pré-tratados e então testados nas reações de conversão de etanol entre 200 °C e 300 °C. Os produtos da reação foram analisados por cromatografia gasosa (CG). Houve produção de metano, propano, propeno...

Immobilization of cobalt phthalocyanine and tetrasulfophthalocyanine onto MCM-41 and MCM-48: effect of immobilization method on catalytic activity

Pirouzmand,Mahtab; Amini,Mostafa M.; Safari,Nasser; Hamoule,Touba
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2013 EN
Relevância na Pesquisa
68.985903%
Cobalt tetrasulfophthalocyanine (CoPcS) was chemically anchored to amine-modified MCM-41 and MCM-48 surface. These mesoporous silica were prepared by hydrothermal procedure. Physical mixtures of CoPc in MCM-41 and in MCM-48 were also prepared for comparison purposes. The four prepared catalysts, 10 wt.% CoPcS/NH2-MCM-41, 10 wt.% CoPcS/NH2-MCM-48, 10 wt.% CoPc/MCM-41 and 10 wt.% CoPc/MCM-48, were characterized by X-ray diffractometry (XRD), diffuse reflectance UV-Vis spectroscopy and BET specific surface analysis. The catalytic activity of the immobilized catalysts was tested in the aerobic epoxidation of cyclohexene. CoPcS/NH2-MCM-41 and CoPcS/NH2-MCM-48 showed relatively high epoxide selectivity but low conversion of cyclohexene compared to CoPc/MCM-41 and CoPc/MCM-48. No leaching of metallophthalocyanine from the catalysts immobilized by chemical bonding into the reaction medium was observed and these catalysts could be reused four times.

A Cu/Al-MCM-41 mesoporous molecular sieve: application in the abatement of no in exhaust gases

Batista,M. S.; Melo,R. A. A.; Wallau,M.; Urquieta-González,E. A.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2005 EN
Relevância na Pesquisa
68.658184%
Propane oxidation and reduction of NO to N2 with propane under oxidative conditions on a Cu-Al-MCM-41 mesoporous molecular sieve and Cu-ZSM-5 zeolites were studied. Both types of catalysts were prepared by ion exchange in aqueous solutions of copper acetate and characterised by X-ray diffraction (XRD), nitrogen sorption measurement, diffuse reflectance ultra-violet spectroscopy (DRS-UV), diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS) of the adsorption of CO on Cu+ and temperature-programmed reduction with hydrogen (H2-TPR). The NO reduction was performed between 200 and 500 ºC using a GHSV = 42,000 h-1. H2-TPR data showed that in the prepared Cu-Al-MCM-41 all the Cu atoms are on the surface of the mesopores as highly dispersed CuO, which results in a decrease in specific surface area and in mesopore volume. H2-TPR together with DRIFTS data provided evidence that in Cu/ZSM-5 catalysts, Cu atoms are found as two different Cu2+ cations: Cualpha2+ and Cubeta2+, which are located on charge compensation sites, and their thermo-redox properties were different from those of Cu atoms in Cu-Al-MCM-41. The specific activity of the Cu2+ exchangeable cations in Cu-ZSM-5, irrespective of their nature, was much greater than that of the Cu2+ in Cu-Al-MCM-41...

Síntese e impregnação de peneiras moleculares Fe MCM-41 derivada de sílica da casca do arroz

Miranda, Auristela Carla de
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
68.95592%
The mesoporous molecular sieves of the MCM-41 and FeMCM-41 type are considered promissory as support for metals used as catalysts in oil-based materials refine processes and as adsorbents for environmental protection proposes. In this work MCM-41 and FeMCM41 were synthesized using rice husk ash - RHA as alternative to the conventional silica source. Hydrothermal synthesis was the method chosen to prepare the materials. Pre-defined synthesis parameters were 100°C for 168 hours, later the precursor was calcinated at 550°C for 2 hours under nitrogen and air flow. The sieves containing different proportions of iron were produced by two routes: introduction of iron salt direct synthesis; and a modification post synthesis consisting in iron salt 1 % and 5% impregnation in the material followed by thermal decomposition. The molecular sieves were characterized by X ray diffraction XRD, Fourier transform infrared spectroscopy FT-IR, X ray fluorescence spectroscopy XFR, scanning electronic microscopy SEM, specific surface area using the BET method, Termogravimetry TG. The kinetic model of Flynn Wall was used with the aim of determining the apparent activation energy of the surfactant remove (CTMABr) in the MCM- 41 porous. The analysis made possible the morphology characterization...

Síntese e caracterização de peneiras moleculares mesoporosas do tipo MCM-41 e AlMCM-41 a partir de fontes alternativas de sílica e de alumínio

Silva, Marta Lígia Pereira da
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
68.85589%
The mesoporous molecular sieves of MCM-41 and AlMCM-41 type are considered as promising support for metal in the refining processes of petroleum-based materials as catalysts and adsorbents for environmental protection. In this work the molecular sieves MCM-41 and AlMCM-41 were synthesized by replacing the source of silica conventionally used, for quartz, an alternative and abundant, and the use of waste from the production of diatomaceous earth, an aluminum-silicate, as a source aluminum, due to abundant reserves of diatomaceous earth in the state of Rio Grande do Norte in the city of Ceará-Mirim, with the objective of producing high-value materials that have similar characteristics to traditional commercial catalysts in the market. These materials were synthesized by the method of hydrothermal synthesis at 100 º C for 7 days and subjected to calcination at 500 º C for 2 hours under flow of nitrogen and air. The molecular sieves were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and thermogravimetric analysis (TG), adsorption of N2 (BET and BJH methods), spectroscopy in the infra red (FTIR), microscopy scanning electron (SEM) and transmission electron microscopy (TEM). The analysis indicated that the synthesized materials showed characteristic hexagonal structure of mesopores materials with high specific surface area and sort and narrow distribution of size of pores; Conselho Nacional de Desenvolvimento Científico e Tecnológico; As peneiras moleculares mesoporosas do tipo MCM-41 e AlMCM-41 são consideradas promissoras como suporte para metais em processos de refino de materiais a base de petróleo...

Preparação e caracterização de catalisadores à base de titânio suportado em MCM-41 para produção de compostos oxigenados através da pirólise catalítica do capim elefante

Fontes, Maria do Socorro Braga
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
68.87337%
In recent years, the area of advanced materials has been considerably, especially when it comes to materials for industrial use, such as is the case with structured porosity of catalysts suitable for catalytic processes. The use of catalysts combined with the fast pyrolysis process is an alternative to the oxygenate production of high added value, because, in addition to increasing the yield and quality of products, allows you to manipulate the selectivity to a product of interest, and therefore allows greater control over the characteristics of the final product. Based on these arguments, in this work were prepared titanium catalysts supported on MCM-41 for use in catalytic pyrolysis of biomass, called elephant grass. The reactions of pyrolysis of biomass were performed in a micro pyrolyzer, Py-5200, coupled to GC / MS, the company CDS Corporation, headquartered in the United States. The catalysts Ti-MCM-41 in different molar ratios were characterized by XRD, TG / DTG, FT-IR, SEM, XRF, UV-visible adsorption of nitrogen and the distribution of particle diameter and specific surface area measurement by the BET method. From the catalytic tests it was observed that the catalysts synthesized showed good results for the pyrolysis reaction.The main products were obtained a higher yield of aldehydes...

Reforma a seco de metano com catalisadores Ni/MCM-41 sintetizados a partir de fontes alternativas de sílica

Montenegro, Danielle Lobo
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: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
69.01885%
The production of synthesis gas has received renewed attention due to demand for renewable energies to reduce the emissions of gases responsible for enhanced greenhouse effect. This work was carried out in order to synthesize, characterize and evaluate the implementation of nickel catalysts on MCM-41 in dry reforming reactions of methane. The mesoporous molecular sieves were synthesized using as silica sources the tetraethyl orthosilicate (TEOS) and residual glass powder (PV). The sieves were impregnated with 10% nickel to obtain the metallic catalysts (Ni/MCM-41). These materials were calcined and characterized by Thermogravimetric Analysis (TG), Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Temperature-Programmed Reduction (TPR) and N2 Adsorption/Desorption isotherms (BET/BJH). The catalytic properties of the samples were evaluated in methane dry reforming with CO2 in order to produce synthesis gas to be used in the petrochemical industry. The materials characterized showed hexagonal structure characteristic of mesoporous material MCM-41 type, being maintained after impregnation with nickel. The samples presented variations in the specific surface area, average volume and diameter of pores based on the type of interaction between the nickel and the mesoporous support. The result of the the catalytic tests showed conversions about 91% CO2...

Síntese, caracterização e aplicação do MCM-41 e A1-MCM-41 na pirólise do resíduo atmosférico de petróleo

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: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
69.19615%
In present work, mesoporous materials of the M41S family were synthesized, which were discovered in the early 90s by researchers from Mobil Oil Corporation, thus allowing new perspectives in the field of catalysis. One of the most important members of this family is the MCM-41, which has a hexagonal array of mesopores with pore diameters ranging from 2 to 10 nm and a high surface area, enabling it to become very promising for the use as a catalyst in the refining of oil in the catalytic cracking process, since the mesopores facilitate the access of large hydrocarbon molecules, thereby increasing the production of light products, that are in high demand in the market. The addition of aluminum in the structure of MCM-41 increases the acidity of the material, making it more beneficial for application in the petrochemical industry. The mesoporous materials MCM-41 and Al-MCM-41 (ratio Si / Al = 50) were synthesized through the hydrothermal method, starting with silica gel, NaOH and distilled water. CTMABr was used as template, for structural guiding. In Al-MCM-41 the same reactants were used, with the adding of pseudoboehmite (as a source of aluminum) in the synthesis gel. The syntheses were carried out over a period of four days with a daily adjustment of pH. The optimum conditions of calcination for the removal of the organic template (CTMABr) were discovered through TG / DTG and also through analysis by XRD...

Síntese e caracterização da peneira molecular MCM-41 contendo terras raras na dessulfurização, utilizando tiofeno como molécula sonda

Alves, José Antônio Barros Leal Reis
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: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
69.10038%
Mesoporous molecular sieves of MCM-41 type are considered as promising support for metal in the refining processes of petroleum-based materials as catalysts and adsorbents for environmental protection. In this work, mesoporous molecular sieves MCM-41 were modified with different rare earth ions (La, Eu e Yb) for the obtaining nanostrutured materials with catalytic properties. The catalysts were synthesized by the hydrothermal method at 100oC for 120 h, presenting, all the samples, in the gel of synthesis molar ratio Si/Ln = 50. The obtained materials after calcination at 500oC for 2 h were characterized by XRD, surface area BET, TG/DTG, FTIR, and hydrothermal stability at 700ºC. The XRD analysis of the catalysts indicated that the materials containing rare earth presented characteristic hexagonal structure of the mesoporous materials of the type MCM-41. The TG curves showed that the decomposition of the structural template occurs in the materials at temperatures lower than 500oC. The samples presented variations as the specific superficial area, average diameter of pores and thickness of the silica wall, as a function of the nature of the rare earth impregnated in the mesoporous material. Hydrotermal stability was evaluated through the exposition of the materials to water vapour at 700°C. The thiophene adsorptions reach a maximum at 80% of conversion and incorporation of the rare earths showed influence in the process. Adsorption capacity followed the sequence: Yb-MCM-41 < La-MCM-41 < Eu-MCM-41 < MCM-41; ; As peneiras moleculares mesoporosas do tipo MCM-41 são consideradas promissoras como suporte para metais em processos de refino de materiais a base de petróleo...

Avaliação da remoção de hidrocarbonetos aromáticos (BTEX) em águas utilizando materiais nanoestruturados do tipo Ti-MCM-41

Morais, Lidiane Alves 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: Dissertação Formato: application/pdf
POR
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Volatile Organic Compounds are pollutants coming mainly from activities that use fossil fuels. Within this class are the BTEX (benzene, toluene, ethylbenzene and xylenes) compounds that are considered hazardous. Among the various existing techniques for degradation of pollutants, there is advanced oxidation using H2O2 generating hidoxil radical ( OH). In this work, the mesoporous material of MCM-41 was synthesized by hydrothermal method and then was used as support, the impregnation of titanium by the method of synthesis with excess solvent to obtain the catalyst Ti-MCM-41. The catalyst was used in the reaction catalyzed removal of BTEX in water using H2O2 as oxidant. The materials were characterized by: XRD, TG/DTG, FTIR, nitrogen adsorption-desorption and FRX-EDX, in order to verify the method of impregnation of the mesoporous titanium support was effective. Catalytic tests were carried out in reactors of 20 mL containing BTEX (100.0 μg/L), H2O2 (2.0 M) and Ti-MCM-41 (2.0 g/L) in acid medium. The reaction occurred for 5 h at 60 °C and analysis were performed by gas chromatography with photoionization detector and static headspace sampler. The characterizations have proven the effectiveness of the synthesis method used and the incorporation of titanium lt in the support. The catalytic tests showed satisfactory results with conversion of more than 95 % for the studied compounds...

Estudo cinético da degradação térmica e catalítica de petróleo pesado usando Al-MCM-41

Oliveira, Aline Araújo Alves 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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69.10038%
The mesoporous nanostructured materials have been studied for application in the oil industry, in particular Al-MCM-41, due to the surface area around 800 to 1.000 m2 g-1 and, pore diameters ranging from 2 to 10 nm, suitable for catalysis to large molecules such as heavy oil. The MCM-41 has been synthesized by hydrothermal method, on which aluminum was added, in the ratio Si/Al equal to 50, to increase the generation of active acid sites in the nanotubes. The catalyst was characterized by X-ray diffraction (XRD), surface area by the BET method and, the average pore volume BJH method using the N2 adsorption, absorption spectroscopy in the infrared Fourier Transform (FT-IR) and determination of surface acidity with application of a probe molecule - n-butylamine. The catalyst showed well-defined structural properties and consistent with the literature. The overall objective was to test the Al-MCM-41 as catalyst and thermogravimetric perform tests, using two samples of heavy oil with API º equal to 14.0 and 18.5. Assays were performed using a temperature range of 30-900 ° C and heating ratios (β) ranging from 5, 10 and 20 °C min-1.The aim was to verify the thermogravimetric profiles of these oils when subjected to the action of the catalyst Al- MCM-41. Therefore...

Síntese e caracterização de peneira molecular mesoporosa mcm-41 com níquel impregnadas e in situ

KLEIN, Karina Vitti
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Química; Educação em Química Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Química; Educação em Química
Tipo: Dissertação Formato: application/pdf
POR
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The new family mesoporosas molecular sieves, known as M41S, have been very studied since its discovery in 1992, with bigger prominence for MCM-41, that had its mesoporosa structure that allows ample applications in catalytic processes. In this work were studied two reactions conditions of preparation of the MCM-41 and three forms of nickel incorporation. In the synthesis of the MCM-41 the hidrotérmico treatment and in conditions was used surrounding, while in the incorporation, was used to impregnation of ions nickel and nanopartículas of nickel oxide, as well as the direct synthesis where the nickel was introduced in the structure of the MCM-41, during the synthesis. The gotten materials had been characterized by elementary nickel analysis, X-ray diffraction, nitrogen adsorption/desorption, FT-IR spectra, thermogravimetric analysis, thermoprogrammed reduction. The characterizations had indicated that it had the formation of the mesoporosa structure with periodic pore system, typical of the MCM-41, in both methods of synthesis, being able to be evidenced the biggest viability of the synthesis of the MCM-41 in the surrounding conditions. It can also be verified that it had nickel incorporation in all samples, independent of as this element was inserted. The introduced samples that had had nickel during the synthesis had presented greater excessively average diameter of pores in relation. After the characterization...

VAPOR-PHASE CATALYTIC CONVERSION OF ETHANOL INTO 1,3-BUTADIENE ON Cr-Ba/MCM-41 CATALYSTS

La-Salvia,N.; Lovón-Quintana,J. J.; Valença,G. P.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2015 EN
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AbstractAl-MCM-41, 16%Ba/Al-MCM-41 and 1.4%Cr-16%Ba/Al-MCM-41 were used as catalysts in the vapor-phase catalytic conversion of ethanol. Physical-chemical properties of the catalysts and the effect of barium and chromium on the Al-MCM-41 activity and 1,3-butadiene yield were studied. The catalysts were characterized by X-ray diffraction (XRD), N2 physisorption (BET method), CO2chemisorption and Fourier transform infrared spectroscopy (FT-IR). When ethanol was completely converted on Al-MCM-41 and 16%Ba/Al-MCM-41, the reaction products showed a high selectivity for ethylene (90-98%). However, on the 1.4%Cr-16%Ba/Al-MCM-41 catalyst, a greater number of reaction products were obtained such as ethylene, acetaldehyde, diethyl ether and 1,3-butadiene. The maximum 1,3-butadiene yield obtained from ethanol reaction was 25% at 723 K and W/FEtOH = 15 g h mol-1. The latter result was obtained in a single step and without addition of reaction promoters (e.g., acetaldehyde, crotonaldehyde, hydrogen) in the feed stream to the reactor.