Molecular Sieves
Mostrando 13-24 de 51 artigos, teses e dissertações.
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13. Membranas de peneira molecular de carbono obtidas pela pirólise de poli(imidas) ramificadas / Carbon molecular sieves obtained from branched poly(imide) pyrolysis
Nesse trabalho obtiveram-se membranas de poli(imida) ramifricada com tamanho de poro ajustável usando melamina como agente de ramificação e indutor da formação de poros. Estas poli(imidas) foram sulfonadas usando-se ácido sulfúrico concentrado eficazmente. Finalmente, obtivemos membranas de carbono molecular por pirólise sob atmosfera inerte das poli
Publicado em: 2010
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14. Síntese e avaliação de sílica tipo M41S contendo cátions CTA em transesterificação catalítica
The investments in the biofuel production have increased a lot in the last years mainly because of smaller damages they cause to the environment in comparison with the derived conventional petroleum fuels. The reaction of biodiesel formation is denominated transesterification and, nowadays that reaction happens in the presence of homogeneous catalyst as the
Publicado em: 2010
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15. Synthesis, characterization and catalytic activity of mesoporous materials Al-MCM-41 in transesterification reaction of cottonseed oil / Síntese, caracterização e avaliação catalítica do aluminossilicato mesoestruturado AI-MCM-41 na transesterificação de óleos vegetais
Molecular sieves have been applied to the processing of triacylglycerols, to produce biofuels. In this context, the mesoporous catalyst Al-MCM-41 was proposed in this work as an alternative to acid heterogeneous transesterification of cottonseed oil with ethanol. This material was prepared using various Si/Al molar ratios (25, 50, 75 and 100) with reaction t
Publicado em: 2010
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16. Desidratação de etanol sobre material nanoestruturado do tipo LaSBA-15
La-incorporated SBA-15 mesopourous molecular sieves (LaSBA-15) were directly synthesized with aim to convert ethanol to ethylene. The samples were characterized by XRD, XRF, nitrogen sorption and acidity, by thermodesorption of n-buthylamine. The results have indicated that all the samples have showed high ordered mesostructure with a large average pore size
Química Nova. Publicado em: 2010
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17. Vanadium-modified molecular sieves: preparation, characterization and catalysis
Vanadium-containing molecular sieves are redox catalysts and are good candidates as substitutes for oxide-supported V2O5 in a number of reactions. These materials have the advantage of presenting better dispersion of vanadium species, as well as shape-selective properties and controllable acidities. They may be prepared by one-pot synthesis or by post-synthe
Química Nova. Publicado em: 2009
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18. Síntese e caracterização de peneiras moleculares mesoporosas do tipo MCM-41 e AlMCM-41 a partir de fontes alternativas de sílica e de alumínio
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
Publicado em: 2009
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19. Síntese, caracterização e aplicação de MCM-41 funcionalizado com diisopropilamina no processo de adsorção do dióxido de carbono
As emissões de CO2 na atmosfera vêm aumentando sucessivamente devido a vários mecanismos provocados pela ação humana, principalmente como a queima de combustíveis fósseis e processos químicos industriais. Isso leva ao aumento da temperatura média na atmosfera, a qual chamamos de aquecimento global. A busca por novas tecnologias para minimizar os imp
Publicado em: 2009
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20. Aplicação de peneiras moleculares contendo cátions orgânicos em catálise básica
This thesis was aimed at studying novel basic catalysts based on molecular sieves containing alkylammonium cations. The studied molecular sieves were faujasite zeolites (FAU) and mesoporous silicate (like MCM-41). The following parameters were evaluated: (1) different alkylammonium cations, (2) different amount of alkylammonium cations and (3) application of
Publicado em: 2008
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21. Síntese e caracterização de materiais nanoporosos para pirólise catalítica de óleos pesados
The present work reports the study of nanoporous structures, aiming at their use in research directed to the current demand of the petroleum industry to value heavy oil. Initially, two ways were chosen for the synthesis of porous structures from the molecular sieves of type Si-MCM-41. In the first way, the structure MCM-41 is precursory for heteroatom substi
Publicado em: 2008
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22. Síntese, caracterização e avaliação catalítica do silicoaluminofosfato SAPO-11 sulfatado
Due to environmental restrictions around the world, clean catalytic technology are of fundamental importance in the petrochemical industry and refineries. Creating the face of this a great interest in replacing the liquid acids for solid acids, so as molecular sieves have been extensively studied in reactions involving the acid catalysis to produce chemical
Publicado em: 2008
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23. Formação de mesoporos na síntese de zeólitas ZSM-5 via nanomoldagem avaliação no craqueamento de n-decano / Formação de mesoporos na síntese de zeólitas ZSM-5 via nanomoldagem avaliação no craqueamento de n-decano
The use of zeolites in the cracking of hydrocarbons is limited because the molecules higher than 0.74 nm do not diffuse in their micropores. In the other hand, molecular sieves as MCM-41, MCM-48 ou SBA-15, whose diameters are up 10 nm for the two formers and up to 30 nm for the last, have low hydrothermal stability and catalytic activity. To overcome those l
Publicado em: 2008
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24. SÃntese de Derivados de Vitamina A utilizando Lipase de Candida antartica Imobilizada (Novozyme 435) / Vitamin A derivatives synthesis using immobilized lipase from Candida antarctica (Novozyme 435)
The main objective of this work was to synthesize vitamin A derivatives through an enzymatic route, as an alternative to chemistry route, more aggressive to the environment. The conversion of retinyl acetate into retinyl palmitate would result in a product with better market acceptance, since it is more stable than the ester used as substrate. Retinyl adipat
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 31/08/2007