Heterogeneous Catalysts
Mostrando 13-24 de 103 artigos, teses e dissertações.
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13. GRAPHENE OXIDE AND A GO/ZnO NANOCOMPOSITE AS CATALYSTS FOR EPOXY RING-OPENING OF EPOXIDIZED SOYBEAN FATTY ACIDS METHYL ESTERS
Abstract In this work, the grapheme oxide (GO) and GO/ZnO nanocomposite were successfully obtained from the oxidation of graphite and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). In the GO/ZnO nanocomposite, the GO sheets were coated with aggregated
Braz. J. Chem. Eng.. Publicado em: 09/12/2019
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14. Hydrogen production from aqueous glycerol using titanate nanotubes decorated with Au nanoparticles as photocatalysts
Abstract: Protonated titanate nanotubes (HTiNts) were synthesized using the hydrothermal method, followed by proton exchange with acid. Gold nanoparticles decorated titanate nanotubes (AuHTiNts) were obtained by the reduction of AuCl4- under vigorous stirring with an aqueous solution of HTiNts containing 1 wt% of ascorbic acid. To investigate the surface str
An. Acad. Bras. Ciênc.. Publicado em: 28/11/2019
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15. Photodegradation study of TiO2 and ZnO in suspension using miniaturized tests
ABSTRACT Miniaturization has been a trend in the instrumentation of chemical analyzes. The interest in miniaturization stems from the perceived benefits of faster, easier, less expensive and less wasteful analyzes than the tradition analyses. Thus, this work proposes a miniaturization of photocatalytic tests using a microplate reader for the analysis of seve
Matéria (Rio J.). Publicado em: 25/11/2019
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16. Síntese de CoFe2O4 sobre os suportes MgAl2O4 e ZSM-5 para uso na degradação de poluente orgânico pelo processo foto-Fenton heterogêneo sob irradiação visível e solar
RESUMO Neste trabalho, ferrita de cobalto (CoFe2O4) foi sintetizada sobre aluminato de magnésio (MgAl2O4) e zeólita ZSM-5 e a atividade catalítica desses materiais na reação foto-Fenton visando a decomposição de um poluente orgânico em solução aquosa foi avaliada. Ferrita de cobalto foi sintetizada sobre os suportes pela rota solvotérmica. Os mate
Matéria (Rio J.). Publicado em: 25/11/2019
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17. Degradation of Acid Red 8 Dye Using Photo-Fenton Reaction Mediated by Titanium Modified Catalysts
Catalysts prepared by co-precipitation of iron and titanium were evaluated in heterogeneous photo-Fenton degradation of the azo dye Acid Red 8 under blacklight irradiation. Materials with different titanium contents (0 < Ti/Fe < 0.6) were characterized using X-ray diffractometry, scanning electron microscopy, X-ray fluorescence spectroscopy, specific surface
J. Braz. Chem. Soc.. Publicado em: 21/10/2019
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18. Gold Catalysis for Selective Hydrogenation of Aldehydes and Valorization of Bio-Based Chemical Building Blocks
Gold catalysts are best known for their selectivity in oxidation reactions, however, there is a promising future for gold in selective hydrogenations. Herein, the hydrogenation of several aldehydes and important bio-based chemical building blocks, namely 5-hydroxymethylfurfural (5-HMF), furfural and vanillin, was performed throughout the combination of Au na
J. Braz. Chem. Soc.. Publicado em: 21/10/2019
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19. CHARACTERIZATION-PERFORMANCE OF ZnO AND ZnO/ZnFe2O4 CATALYST USING ARTIFICIAL AND SOLAR LIGHT FOR MERCURY (II) REDUCTION
Abstract This study describes the application of ZnO commercial oxide and ZnO/ZnFe2O4 mixed oxides to reduce the mercury ion (Hg2+) in the aqueous phase. The catalysts synthesized were characterized by thermogravimetric analysis, adsorption and desorption of N2, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, photoac
Braz. J. Chem. Eng.. Publicado em: 30/09/2019
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20. Simple Niobium Catalysts Applied in Reflux and Ultrasound-Assisted Systems for Biofuel Synthesis
Using niobium compounds as heterogeneous catalysts in biodiesel production is a promising methodology from economic and environmental viewpoints. However, the application of niobium catalysts still is a challenge due to the high temperatures and pressures for moderate biofuel yields. Therefore, easily handled and applied materials have been developed to opti
J. Braz. Chem. Soc.. Publicado em: 16/09/2019
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21. Different Strategies to Anchor Organotin Methoxides on Silica and Their (Re)Use as Heterogeneous Catalysts for Transesterification Reactions
Catalysts were prepared by the heterogenization of the tributyltin(IV) methoxide (n-Bu3Sn(OMe)) and dibutyltin(IV) dimethoxide (n-Bu2Sn(OMe)2) on silica by two strategies: (i) anchoring of the organotin(IV) compounds on silica and (ii) anchoring of the organotin(IV) compounds on a silica gel functionalized with mercaptopropyl groups (SiO2–SH). The characte
J. Braz. Chem. Soc.. Publicado em: 16/09/2019
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22. SYNTHESIS AND THEORETICAL STUDY OF HPW CATALYSTS SUPPORTED ON NIOBIA CALCINATED AT 500 AND 600 ºC
Keggin heteropolyacids (HPW) supported on niobia have been considered for both homogeneous and heterogeneous catalysis due to its special features, like the strong Brönsted acidity, low volatility, high activity and high selectivity for various reactions in comparison with mineral acids. Literature reports many different preparation methods for these cataly
Quím. Nova. Publicado em: 26/08/2019
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23. Síntese, caracterização e modificação da hidroxiapatita com zinco para aplicação na reação de esterificação
RESUMO A hidroxiapatita tem se destacado entre os materiais cerâmicos devido a sua versatilidade estrutural, pois permite a substituição do Ca2+ ou do PO43-da sua estrutura possibilitando diversas aplicações. A utilização da hidroxiapatita como suporte e, ou catalisador tem recebido destaque como tema de pesquisa. Com isso, o objetivo deste trabalho f
Matéria (Rio J.). Publicado em: 20/05/2019
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24. Methyl Esters Production by Heterogeneous Catalyst Mixtures of CaO/Nb2O5 with Simulation of Analysis of Environmental Impacts
The conventional biodiesel process, although it reaches high conversion yields and productivity, faces problems related to the use of homogeneous catalysts. This work aims to study mixtures of calcium oxide (CaO) and niobium oxide (Nb2O5) as the heterogeneous catalyst. It was used a full 23 factorial design with four central points to analyze how the mass pe
J. Braz. Chem. Soc.. Publicado em: 2019-03