Hydrotalcites
Mostrando 1-12 de 16 artigos, teses e dissertações.
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1. Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification
Abstract The innumerous advantages of heterogeneous catalysts employed in biodiesel production have stimulated the search for a solid catalyst capable of replacing the industrially used homogeneous catalysts. This paper investigates the effect of the sol-gel method in the catalytic activity and stability of Li-MgAl mixed oxides prepared by the “in situ”
Braz. J. Chem. Eng.. Publicado em: 2018-01
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2. Synergistic Interactions between Ti-OOH and (PO4[WO2(O2)]4)3- of HPW/Zn-Ti Hydrotalcites: Efficient Heterogeneous Catalysts for the Epoxidation of Fatty Acid Methyl Ester
A series of HPW/Zn-Ti layered double hydroxides (LDHs) were prepared by immobilizing phosphotungstic acid (HPW) on the Zn-Ti LDHs. Systematically characterizations were performed to elucidate their structure. These HPW/Zn-Ti LDHs hybrids were used as heterogeneous catalysts in the epoxidation of fatty acid methyl ester (FAMEs) with H2O2. The HPW/Zn-Ti LDHs s
J. Braz. Chem. Soc.. Publicado em: 2018-01
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3. ÓXIDOS METÁLICOS DERIVADOS DE MATERIAIS TIPO HIDROTALCITAS CONTENDO Ga3+ COMO CATALISADORES PARA SÍNTESE DE BIODIESEL ETÍLICO
Summary: The synthesis of like-hydrotalcites materials (layered double hydroxides - LDHs) with molecular formula MgxM3+y(CO3)(OH)16·4H2O in different ratios Mg2+/M3+ where M3+ is Al3+, Ga3+ or both was carried out by the coprecipitation method to be applied in the transesterification reactions for synthesis of ethyl biodiesel from soybean oil and ethanol. T
Quím. Nova. Publicado em: 2017-06
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4. Ce - promoted catalyst from hydrotalcites for CO2 reforming of methane: calcination temperature effect
Ce-promoted Ni-catalysts from hydrotalcites were obtained. The effect of calcination temperature on the chemical and physical properties of the catalysts was studied. Several techniques were used to determine the chemical and physical characteristics of oxides. The apparent activation energies of reduction were determined. Catalytic experiments at 48 L g-1h-
Química Nova. Publicado em: 2012
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5. Produção de monoéster via etanólise por hidrotalcitas termoativadas : síntese e caracterização
Among biofuels of the 1st generation, biodiesel stands out for its equivalent features to those of mineral diesel, however less polluting. It can be obtained by transesterification of triglyceride fats or vegetable oils by (m)ethanolysis. Aiming at improving the chemical process, different types of catalysis have been studied: i) homogeneous (acid e.g. H2SO4
Publicado em: 2011
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6. Efecto del pH en la síntesis de hidroxiapatita en presencia de microondas
Synthetic hydroxyapatite, Ca10(PO4)6(OH)2, is a biomaterial used to reconstruct damaged bone tissue or to recover protheses. Indeed, the chemical composition and structure is similar to the mineral phase contained in the scheleton. This similarity favors the formation of bonds with the bone, it becomes then a biocompatible material. Hydroxyapatite may be obt
Matéria (Rio de Janeiro). Publicado em: 2010
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7. Preparation and characterization of hydrotalcites-like compounds with metals Ni-Fe-Cu / Preparação e caracterização de compostos tipo hidrotalcita com metais Ni-Fe-Cu
Sistemas ternários tipo hidrotalcita contendo metais de transição Ni, Fe e Cu tendo o ânion interlamelar o carbonato foram preparados através de um estudo sistemático de composição e parâmetros de síntese. Diferentes quantidades de Cu foram introduzidas na camada tipo brucita da hidrotalcita, sendo estas quantidades de 10, 20, 30, 40 e 50 % em rela
Publicado em: 2009
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8. Influence of basic properties of Mg,Al-mixed oxides on their catalytic activity in knoevenagel condensation between benzaldehyde and phenylsulfonylacetonitrile
The catalytic performance of Mg,Al-mixed oxides (MO20, MO25 and MO33) derived from hydrotalcites was evaluated in the Knoevenagel reaction between benzaldehyde and phenylsulfonylacetonitrile at 373 and 383 K. The best results were obtained for the sample MO20 that presented the highest basic sites density and external area and the smallest crystallite sizes.
Química Nova. Publicado em: 2009
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9. Estudo da adsorção de água em compostos tipo-brucita por cálculos ab initio
The anionic clays, also known as layered double hydroxides (LDH) or hydrotalcitelike compounds, constitute a family of materials whose chemical formula can be represented by: [M2+ (1x) Me3+ x(OH)2]x+ . Amx/ m .nH2O. These compounds have hydroxide planes, or layers, which become permanently positively charged by the substitution of divalent cations M2+ by tri
Publicado em: 2008
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10. Compósitos magnéticos baseados em hidrotalcitas para a remoção de contaminantes aniônicos em água
In this work the adsorption features of hydrotalcites (Al, Mg- CO3) and the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. These magnetic composites can be used as adsorbents for anionic contaminants in water and subsequently removed from the medium by a simple magnetic process. The magnetic hydrotalcite
Química Nova. Publicado em: 2007-10
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11. Preparação, caracterização e propriedades cataliticas de hidrotalcitas MgAICr calcinadas na conversão de etanol / Preparation, characterization and catalytic properties of calcined MgAICr hydrotalcites in ethanol conversion
Materiais do tipo hidrotalcita Mg1-x(Al,Cr)x(OH)2(CO3)x/2yH2O foram sintetizados por coprecipitação a partir de nitratos de magnésio, alumínio e cromo. Os sólidos foram calcinados, caracterizados e testados na conversão de etanol. Na preparação, alumínio foi substituído por cromo na hidrotalcita MgAl nas proporções de 0, 5, 10, 50, 80 e 100% e as
Publicado em: 2007
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12. "Aplicação de catalisadores de níquel e cobalto preparados via precursores do tipo hidrotalcita nas reações de reforma a vapor, oxidação parcial e reforma oxidativa do metano" / "Application of nickel and cobalt catalysts prepared via hydrotalcite-type precursors in the reactions of steam reforming, partial oxidation and oxidative reforming of methane"
One of the most important applications of methane is the syngas production, a mixture of H2 and CO. Three processes can lead to syngas formation from methane: steam reforming, CO2 reforming and partial oxidation. Various non-noble metal catalysts were studied in these processes, although the carbon deposition or the metal sinterization is always observed. Ca
Publicado em: 2007