Mesoporosity
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. Optimization and Study of the Response Surface of Properties for the Synthesis of ZSM-5 Zeolites with Hierarchical Pore Structure Obtained by Desilication
Hierarchical ZSM-5 zeolites were prepared by alkali treatment (desilication) at two temperatures, two reaction times, and two NaOH concentrations. A 23 factorial design was used to study the effect of these variables on the crystallinity, microporosity, and mesoporosity of the zeolite due to the desilication treatment. The factorial design analysis showed th
J. Braz. Chem. Soc.. Publicado em: 2021-06
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2. Reordering of Depolymerized Silicates as Adsorbents for Large Nitrogen Compounds
The adsorption capacities of two synthesized zeolites (crystalline ZSM-5 and semi-crystalline faujasite Y) for a mixture of indole, quinoline and carbazole were studied. The different samples obtained show different crystalline degree, mesoporosity and Si/Al ratios. The synthesis procedure is based on the simultaneous depolymerization of a mixture of high su
J. Braz. Chem. Soc.. Publicado em: 2021-01
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3. Synthesis of ordered mesoporous silica MCM-41 with controlled morphology for potential application in controlled drug delivery systems
Resumo O MCM-41 é uma das cerâmicas mesoporosas mais estudadas para sistemas de liberação controlada de fármacos. Sua elevada área superficial específica e mesoporosidade permitem alta capacidade de adsorção. Apesar dos inúmeros trabalhos publicados na área biomédica, até o presente momento não há relatos de aplicações comerciais do MCM-41.
Cerâmica. Publicado em: 06/06/2019
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4. Generación de mesoporosidad en zeolitas ZSM-11, BETA e Y por tratamiento alcalino
ABSTRACT Zeolites, Y, ZSM-11 and BETA, widely used in refineries and petrochemical processes, fine chemistry and environmental processes were subjected to an alkaline treatment of desilication, in order to generate mesoporosity in the structure. The process used consisted of treating samples with an aqueous solution of NaOH at 65 ° C for 30 minutes. An exch
Matéria (Rio J.). Publicado em: 19/07/2018
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5. Temporal Variation of Soil Physical Quality under Conventional and No-Till Systems
ABSTRACT: Determination of soil physical quality (SPQ) is very important because it is related to many important soil processes. However, it is not clear which indicators should be considered in this evaluation, and information about temporal variation of SPQ under different soil tillage systems is scarce. The aim of this study was to determine the effects o
Rev. Bras. Ciênc. Solo. Publicado em: 16/04/2018
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6. DESENVOLVIMENTO DE MATERIAIS HÍBRIDOS MICRO-MESOPOROSOS DO TIPO ZSM-12/MCM-41
Micro-mesoporous hybrid materials of ZSM-12/MCM-41 type with different micro- and mesoporosity contributions were prepared by a procedure that uses the desilication of the zeolite in an alkaline medium, followed by recrystallization onto the mesostructure, where the zeolite is used as the silica source in the formation of mesoporous phase. The materials were
Quím. Nova. Publicado em: 2015-03
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7. Geração de mesoporos em zeólitas ZSM-5 e seus efeitos na conversão do etanol em olefinas
Developing mesoporosity in HZSM-5 zeolites is an alternative for improving their catalytic performance on chemical reactions. In this work, alkaline and thermal treatments were used to produce mesoporosity. These treatments increased mesoporous area and volume. They also influenced the acid properties of the samples. Concerning catalytic performance, treatme
Quím. Nova. Publicado em: 2012
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8. Materials hierarchically structuralized with mesoporosa cubical phase: synthesis, characterization and use as support in the immobilization of enzyme HRP / Materiais hierarquicamente estruturados com fase cúbica mesoporosa: síntese, caracterização e uso como suporte na imobilização da enzima HRP
Hierarchical silica porous materials have been successfully synthesized using polystyrene nanospheres as macropore template, triblock copolymer Pluronic F127 as mesopore template, tetramethyl orthosilicate as silica source and ethanol as cosurfactant. The obtained materials were characterized by XRD, TG-DTA, N2 adsorption, Hg porosimetry, SEM, HRSEM, TEM and
Publicado em: 2009
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9. Influência do método de preparação nas propriedades do óxido de ferro suportado. / Influence of preparation method on properties of iron oxide supported.
Styrene is one of the most important basic chemicals to produce valuable commodities such as polystyrene, acrylonitrile-butadiene-styrene and styrene-butadiene-styrene. It is commercially produced by the dehydrogenation of ethylbenzene in the presence of large amounts of steam at high temperatures of 600-700 oC. This process is thermodynamically limited and
Publicado em: 2005
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10. Sintese e caracterização de ferrissilicatos mesoporosos
MCM-41 structured mesoporous ferrisilicates were synthesized by polymerization of sodium silicate over supramolecular arrays of CTABr, used as structure-directing agent. Alternatively, tetramethylammonium silicate was used as source of silicate. The condensation of the silicate was stimulated by decreasing the pH with one of the following acids: hydrofluoric
Publicado em: 2002
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11. Preparation of silica by sol-gel method using formamide
In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS) was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide of 1/1. The performance of formamide in obtaining crack-fre
Materials Research. Publicado em: 2001-07