Molecular Sieves
Mostrando 1-12 de 51 artigos, teses e dissertações.
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1. Influence of Crystallization and Ageing Time on the Reproducibility of Mesoporous Molecular Sieve SBA-15
ABSTRACT The study aimed to assess how the crystallization and ageing times in SBA-15 synthesis influence the reproducibility and particle size of mesoporous molecular sieves. X-ray diffraction showed that higher crystallization times provide greater reproducibility of mesoporous silica, due to the fact that there is no significant variation in the width and
Matéria (Rio J.). Publicado em: 10/06/2019
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2. SYNTHESIS OF 2,6-DIMETHYLNAPHTHALENE OVER SAPO-11, SAPO-5 AND MORDENITE MOLECULAR SIEVES
Abstract Shape-selective methylation of naphthalene over SAPO-11, SAPO-5 and mordenite molecular sieves were carried out in a fixed-bed flow reactor under atmospheric pressure. Methanol and mesitylene were used as methylation and solvent agents. The experiment results showed that SAPO-11 exhibited higher stability, higher selectivity of 2,6-dimethylnaphthale
Braz. J. Chem. Eng.. Publicado em: 2017-01
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3. Comparison of Kinetic Study of CTMA+ Removal of Molecular Sieve Ti-MCM-41 Synthesized with Natural and Commercial Silica
This work aimed to determine and compare the apparent activation energy, involved in thermal decomposition of CTMA+ from the pores of Ti-MCM-41 synthesized by two different source of silica in order to evaluate their influence in the template removal. The molecular sieves Ti-MCM-41 were synthesized using rice husk ash (RHA), as alternative low cost source of
Mat. Res.. Publicado em: 2015-06
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4. Molecular Sieves Mediated Green Per-O-Acetylation of Carbohydrate Templates and Lipase Catalyzed Regioselective Alcoholysis of 2,3,5-Tri-O-Acetyl-D-Ribonolactone
The per-O-acetylation of D-ribono-1,4-lactone and representative carbohydrates through the combination of acetic anhydride and molecular sieves under solvent-free conditions is demonstrated. The use of 13X/KCl molecular sieves as the heterogeneous catalyst was found to be more efficient than the excess of pyridine normally employed in the conventional method
J. Braz. Chem. Soc.. Publicado em: 2015-04
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5. Simulation of ethanol extractive distillation with mixed glycols as separating agent
Extractive distillation is an alternative for ethanol dehydration processes that has been shown to be more effective than azeotropic distillation and, in close proximity, to be very competitive against the process that uses adsorption with molecular sieves. Glycols have been shown to be the most effective solvents in extractive distillation, mainly ethylene
Braz. J. Chem. Eng.. Publicado em: 2014-03
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6. Adsorção de CO2 em peneiras moleculares micro e mesoporosas
Microporous molecular sieves of type Y, Beta, ZSM-5, ZSM-12 and ZSM-35, and mesoporous molecular sieves of type MCM-41 and MCM-48, and these sieves modified with triethanolamine and ethylenediamine were obtained and characterized by XRD, FTIR, TGA and nitrogen adsorption. The adsorption tests were performed by the gravimetric method under a stream of CO2 at
Quím. Nova. Publicado em: 2014
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7. DESENVOLVIMENTO DE PENEIRAS MOLECULARES MESOPOROSAS DO TIPO MCM-41 E MCM-48 IMPREGNADAS COM AMINAS PARA UTILIZAÇÃO NA ADSORÇÃO DE CO2. / DEVELOPMENT OF TYPE MESOPOROUS MOLECULAR SIEVES MCM-41 AND MCM-48 IMPREGNATED WITH AMINES FOR USE IN ADSORPTION CO2.
O aumento significativo das emissões de dióxido de carbono na atmosfera vem acentuando o efeito do aquecimento global. A busca por fontes energéticas que minimizem as emissões é de grande importância, como também o uso de ações complementares como processos para captura deste gás das principais fontes emissoras. Dentre alguns processos já bem conh
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 25/07/2012
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8. Iodeto de potássio suportado em peneiras moleculares mesoporosas (SBA-15 e MCM-41) como catalisador básico para síntese de biodiesel
Iodide potassium incorporated on mesoporous molecular sieves (SBA-15 and MCM-41) was used as heterogeneous catalysts in the transesterification of sunflower oil under different conditions of reaction time and ratio catalyst/oil (w/w). The results have showed that the system supported in SBA-15 has been more active than the supported in MCM-41, promoting a co
Química Nova. Publicado em: 2012
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9. Simulação do processo de adsorção psa para separação da mistura etanol-água / Simulation of the adsorption process psa for separation of ethanol-water mixtures
One of the problems with ethanol production is the high energy cost which is associated with the separation of ethanol due to of excess water and the existence of an azeotrope in the mixture ethanol-water, by conventional distillation the mixture can be separated up to 95% weight. Currently, there is great interest in the development of technological process
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 04/07/2011
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10. Mesoporous molecular sieve MCM-41 synthesis from fluoride media
A study of the synthesis of MCM-41 mesoporous molecular sieves in fluoride media, having no alkaline metal ions, was performed by changing the gel composition and crystallization temperature and time. X-ray diffraction and nitrogen adsorption analyses showed that highly ordered MCM-41 samples were obtained from gels with a NH4OH/SiO2 molar ratio in the 3.25-
Brazilian Journal of Chemical Engineering. Publicado em: 2011-12
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11. Efficient synthesis of sulfonamide derivatives on solid supports catalyzed using solvent-free and microwave-assisted methods
In this work we report the synthesis of sulfonamide derivatives using a conventional procedure and with solid supports, such as silica gel, florisil, alumina, 4Å molecular sieves, montmorillonite KSF, and montmorillonite K10 using solvent-free and microwave-assisted methods. Our results show that solid supports have a catalytic activity in the formation of
Química Nova. Publicado em: 2011
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12. Efeitos da incorporação de peneiras moleculares 3A, 4A, 5A e 13X em membranas compósitas de quitosana/poli(vinil álcool)
The composite membranes prepared via incorporation of 12.5% of molecular sieves 3A, 4A, 5A and 13X into chitosan/poly(vinyl alcohol) (1:1). The composite membranes were immersed in the cross-linker sulfuric acid in order to acquire high proton conductivity for applications in electrolytes in PEMCF and DMF. The influence of the molecular sieves on the structu
Química Nova. Publicado em: 2010