Catalysts
Mostrando 13-24 de 901 artigos, teses e dissertações.
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13. The Influence of the Platinum Weight Percentage in the Catalyst Formulation on the Performance of a High Temperature Ethanol Electroreformer Based on H3PO4 Doped Polybenzimidazole for Green Hydrogen Production
A vapor-fed high temperature proton exchange ethanol electroreformer has been developed based on the use of a H3PO4-doped polybenzimidazole membrane to produce green hydrogen. As a key parameter, this article describes the influence of platinum weight percent (wt.%) in the catalyst formulation from different commercial catalysts (20, 40, 60, 80 wt.% Pt/C and
Journal of the Brazilian Chemical Society. Publicado em: 2022
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14. Iron Cobaltite (FeCo2O4) Nanocatalysts for Water-Oxidation: Effects of Annealing Temperature on Catalytic Properties
The development of efficient, stable, and non-precious metal water oxidation catalysts (WOCs) is a matter of importance for sustainable energy research. In this work, iron cobaltite (FeCo2O4) nanoparticles were prepared by the coprecipitation method, and we present the effect of heat treatment (250, 350, 450, 650 and 900 °C) on the catalytic properties. Cat
Journal of the Brazilian Chemical Society. Publicado em: 2022
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15. Biodiesel: An Overview II
The crescent number of scientific articles published per year shows that research on biodiesel continues to play an important role to support the growing demand for this biofuel. The second edition of Biodiesel: An Overview presents the worldwide research in the last 15 years. Microalgae biomass is the most studied raw material alternative in this period and
J. Braz. Chem. Soc.. Publicado em: 2021-07
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16. Effects of Polycyclic Aromatic Hydrocarbon Pendant-Armed Ligands on the Catecholase Activity of Dinuclear Copper(II) Complexes
Herein, we present three new binuclear copper(II) complexes containing different polycyclic aromatic hydrocarbons, able to catalyze the oxidation of 3,5-di-tert-butylcathecol, a model substrate for catechol oxidase. The ligands and complexes were successful characterized in solid and solution states. The structure of C1 was determined by X-ray crystallograph
J. Braz. Chem. Soc.. Publicado em: 2021-05
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17. Synthetic Studies toward (−)-Cleistenolide: Highly Stereoselective Synthesis of New γ-Lactone Subunits
This study describes the stereoselective synthesis of two new γ-lactones in 6 and 3 steps and 19 and 32% yield, respectively, directed toward the total synthesis of the natural product (−)-cleistenolide. The starting material was an enantiomerically pure diacetonide diol, derived from d-mannitol with the required stereocenters for (−)-cleistenolide synt
J. Braz. Chem. Soc.. Publicado em: 2021-04
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18. MODIFICAÇÃO QUÍMICA DO POLIPROPILENO ATRAVÉS DA INTRODUÇÃO DE GRUPOS SULFÔNICOS PARA APLICAÇÃO COMO CATALISADOR EM REAÇÕES DE ESTERIFICAÇÃO
In this work, the chemical modification of pristine polypropylene was carried out through sulfonation reactions with concentrated sulfuric acid (PPS1) and fuming sulfuric acid (PPS2), for production of heterogeneous catalysts used in esterification reactions. Fourier transform infrared spectroscopy, elemental analysis, degree of substitution and ion exchange
Quím. Nova. Publicado em: 2021-04
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19. IMIDAZOL E CATÁLISE: UM PAR PERFEITO
The imidazole (IMZ) ring presents several chemical properties that turns it into a versatile acid-basic/nucleophilic catalyst. The discovery of the biological properties of histidine (amino acid with IMZ ring) instigates the study of this class of compounds. It is found in nature in several enzymes such as chymotrypsin and RNAses due to these properties. Thi
Quím. Nova. Publicado em: 2021-03
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20. New Greener Method for the Preparation of Heteropolyacid Compounds (HPW) Modified with Metallic Tin and Application in the Lactic Acid Esterification Reaction
The main objective of this work was to design an innovative method to prepare heterogeneous heteropolyacid catalysts. The heteropolyacid H3PW12O40 (HPW) was modified with tin(II) by two methodologies: a conventional aqueous ion-exchange (CS) and a redox solid-state (SS). In both cases, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD
J. Braz. Chem. Soc.. Publicado em: 2021-03
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21. Properties of Cu-Co Composite Catalysts for Synthesis of Aliphatic Alcohols
Cu-Co-containing cellulose-based carbon composite materials (Cu-Co/Cel) were formed by a matrix isolation method. Using X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared-Fourier spectroscopy (IR-Fourier spectroscopy), and non-isothermal research methods, the physicochemical properties of the composites were established. The catalysts
J. Braz. Chem. Soc.. Publicado em: 2021-02
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22. Brazilian Mineral Clays: Classification, Acid Activation and Application as Catalysts for Methyl Esterification Reactions
In this study, three raw Brazilian clays from João Pessoa, Paraíba State (Aço AP, AVL and Verde Lodo) were characterized before and after purification and acid activation. Several instrumental techniques were used, and the raw clays were classified as dioctahedral smectites with different compositions, where the AVL sample had the highest content of montm
J. Braz. Chem. Soc.. Publicado em: 2021-01
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23. Abscesso retrofaríngeo complicado: uma causa atípica de mielopatia
In order to increase the specific surface area of Pt-Rh-Pd / Al2O3 automotive three-way catalyst and improve its low-temperature reduction performance, Ce, Zr, and La were added to the Pt-Rh-Pd / Al2O3 catalyst to prepare the fibrous Pt-Rh-Pd / CeO2-ZrO2-La2O3-Al2O3 catalyst via an electrospinning technique. The fibrous catalysts were characterized by XRD, F
Arq. Neuro-Psiquiatr.. Publicado em: 2021-01
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24. Falha do Solitaire Stent retriever durante a trombectomia: há alguma imagem que pode predizer a não recanalização?
In order to increase the specific surface area of Pt-Rh-Pd / Al2O3 automotive three-way catalyst and improve its low-temperature reduction performance, Ce, Zr, and La were added to the Pt-Rh-Pd / Al2O3 catalyst to prepare the fibrous Pt-Rh-Pd / CeO2-ZrO2-La2O3-Al2O3 catalyst via an electrospinning technique. The fibrous catalysts were characterized by XRD, F
Arq. Neuro-Psiquiatr.. Publicado em: 2021-01