Catalyst
Mostrando 13-24 de 1204 artigos, teses e dissertações.
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13. Fast Catalytic Pyrolysis of Tetradecanoic Acid: Formation of Ketones as Intermediate Compounds in the Production of Hydrocarbons
This work aimed to compare two different catalysts in the production of a long chain ketone, intermediate in the production of hydrocarbons, during pyrolysis of tetradecanoic acid as a model fatty acid. The studied variables were the temperature, 450 and 600 ºC, and catalysts, γ-Al2O3 and Nb2O5, the latter has never been studied under such conditions. Pyro
Journal of the Brazilian Chemical Society. Publicado em: 2022
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14. Tuning the Photocatalytic Activity of Tin Oxide through Mechanical Surface Activation
Tin oxide (SnO2) nanoparticles were synthesized by the co-precipitation method and mechanically modified by high-energy ball milling. The experimental results demonstrate that the collision with zirconia balls produces slight changes in the crystalline, electronic, morphological, and surface properties of SnO2, which lead to an increase in the redox potentia
Journal of the Brazilian Chemical Society. Publicado em: 2022
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15. Pretreatment and Enzymatic Saccharification of Water Hyacinth, Sugarcane Bagasse, Maize Straw, and Green Coconut Shell Using an Organosolv Method with Glycerol and FeCl3
A method to pretreatment of biomasses using glycerol as a green solvent was developed. Optimization of organosolv pretreatment was performed using a 23 factorial design, investigating synergism among the variables particle size (from < 0.85 to > 2.0 mm), FeCl3 concentration (0.025-0.175 mol L-1), and temperature (160-220 °C). Although the effects of the var
Journal of the Brazilian Chemical Society. Publicado em: 2022
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16. Thermal, structural and optical properties of magnetic BiFeO3 micron-particles synthesized by coprecipitation method: heterogeneous photocatalysis study under white LED irradiation
Abstract Bismuth ferrite, BiFeO3 (BFO) prepared via a coprecipitation method, was used as an effective photocatalyst for the degradation of methylene blue (MB) using a white light-emitting diode (LED-50 W) lamp. The as-prepared material was characterized by TGA, XRD, SEM-EDX, FTIR, and UV-vis-DRS techniques. The effects of experimental key parameters such as
Cerâmica. Publicado em: 2022
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17. Novel Greener Microwave-Assisted Deprotection Methodology for the 1,3-Dioxolane Ketal of Isatin Using Calix[n]arenes
In this work, the combined use of p-sulfonic acid-calix[n]arene and microwave energy to hydrolyze the 1,3-dioxolane ketal of isatin was evaluated with excellent results. This is the first time that p-sulfonic acid-calix[n]arene has been used as the catalyst in a ketal hydrolysis reaction and the deprotection of the ketone carbonyl of isatin is reported. The
Journal of the Brazilian Chemical Society. Publicado em: 2022
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18. Preparation of SAPO-34-Based Catalyst for Conversion of Fructose to 5-Hydroxymethylfurfural
Solid acid-catalyzed dehydration of fructose to produce 5-hydroxymethylfurfural (5-HMF) has been a hotspot in biomass conversion research in recent years. In this study, a novel SAPO-34-based catalyst was prepared by consecutive steps of titanium doping, sulfuric acid impregnation, and sulfonic acid functionalization. Characterization of the catalyst with X-
J. Braz. Chem. Soc.. Publicado em: 2021-08
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19. Ketones as Electrophile in Nitroaldol Reaction: Synthesis of β,β-Disubstituted- 1,3-dinitroalkanes and Allylic Nitro Compounds
Abstract β,β-Disubstituted-1,3-dinitro compounds were obtained exclusively with an overall yield of 83% through a domino nitroaldol/elimination/1,4-addition process, when excess nitromethane was added to cyclohexanone or butanone using DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), as a basic catalyst. On the other hand, β-nitroalcohols could be obtained in 30
J. Braz. Chem. Soc.. Publicado em: 2021-08
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20. Synthesis of Triazoles by Electro-Assisted Click Reaction Using a Copper Foil Electrode
This paper presents an innovative pathway for the synthesis of triazoles using the well-known “click chemistry” assisted by the electrochemical oxidation of metallic Cu0. The click reaction is used to couple a wide range of biological interest compounds. In this case, faster and less polluting methods for a biological environment was achived by in situ C
J. Braz. Chem. Soc.. Publicado em: 2021-07
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21. Liquid Phase Nitration of Benzene Catalyzed by a Novel Salt of Molybdovanadophosphoric Heteropolyacid
A highly efficient and reusable catalyst QA-HPMV was successfully prepared by the reaction of quinoline-2-formic acid (QA) with molybdovanadophosphoric heteropolyacid (H4PMo11VO40, HPMV) for the nitration of benzene. The physical and chemical properties of the sample was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectrosco
J. Braz. Chem. Soc.. Publicado em: 2021-06
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22. Gold Nanorods Capped with Different Ammonium Bromide Salts on the Catalytic Chemical Reduction of p-Nitrophenol
It is known that the reactivity of the nanocatalytic systems is related to the particle size and shape and also to the features of the capping agents on the nanostructures. In this study, gold nanorods (AuNRs) were synthesized by the seed-mediated method using different tetra-alkylammonium bromide salts as capping agents, that are, cetyltrimethylammonium (CT
J. Braz. Chem. Soc.. Publicado em: 2021-06
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23. Porosity of CHA Zeolite Driving the Formation of Polyaromatic Coke Species in the Methanol to Olefins Reaction
The pore size of the chabazite structure is exceptionally suitable for the methanol to olefins (MTO) reaction. The reaction has an induction period required for the formation of a hydrocarbon pool (HP), usually composed of aromatic compounds of different sizes. HP is alkylated by methanol and afterward cracked, leading to the formation of olefins. Despite th
J. Braz. Chem. Soc.. Publicado em: 2021-05
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24. 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