Catalysis
Mostrando 37-48 de 1422 artigos, teses e dissertações.
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37. Controlled synthesis of noble metal nanomaterials: motivation, principles, and opportunities in nanocatalysis
ABSTRACT This review describes some principles of the controlled synthesis of metal nanoparticles, focusing on how the fundamental understanding of their synthesis in the solution-phase can be put to tailor size, shape, composition, and architecture. The maneuvering over these parameters not only enable the tuning of properties, but also the maximization and
An. Acad. Bras. Ciênc.. Publicado em: 16/04/2018
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38. A Novel Electrochemical Aptamer Biosensor Based on DNAzyme Decorated Au@Ag Core-Shell Nanoparticles for Hg2+ Determination
As a kind of important water pollutant, heavy metal ions have a detrimental effect on the health of human. In this study, Au@Ag core-shell nanoparticles were synthesized by simple reduction of Ag + around Au nanoparticles and functionalized by DNAzyme. Based on thymine-Hg2+-thymine binding mode, a sensitive aptamer biosensor was constructed by utilizing func
J. Braz. Chem. Soc.. Publicado em: 2018-02
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39. FATTY ACID ETHYL ESTERS FROM MICROALGAE OF Scenedesmus ecornis BY ENZYMATIC AND ACID CATALYSIS
Microalgae are an indispensable food source for the various growth stages of mollusks, crustaceans, and several fish species. Using a microalgae biomass present in the Amazonian ecosystem (Macapá-AP), we study extraction methods for fatty acid such as solvent extraction (magnetic stirring and/or Soxhlet) and/or hydrolysis (acid and/or enzymatic catalysis) f
Quím. Nova. Publicado em: 2018-01
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40. ESTERIFICAÇÃO E TRANSESTERIFICAÇÃO HOMOGÊNEA DE ÓLEOS VEGETAIS CONTENDO ALTO TEOR DE ÁCIDOS GRAXOS LIVRES
The high free fatty acids content in some vegetable oils can have a negative impact in the sustainable production of biodiesel. The previous treatment of these feedstock oils can contribute to the reduction of the process total costs as well as the environment, turning the biodiesel a more competitive in relation to the fossil diesel. The aim of this work wa
Quím. Nova. Publicado em: 2018-01
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41. Organic Synthesis: New Vistas in the Brazilian Landscape
ABSTRACT In this overview, we present our analysis of the future of organic synthesis in Brazil, a highly innovative and strategic area of research which underpins our social and economical progress. Several different topics (automation, catalysis, green chemistry, scalability, methodological studies and total syntheses) were considered to hold promise for t
An. Acad. Bras. Ciênc.. Publicado em: 2018
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42. Biodiesel Glycerides from the Soybean Ethylic Route Incomplete Conversion on the Diesel Engines Combustion Process
An evaluation was made to determine the effect of the glycerides presence resulting from the incomplete conversion of soybean biodiesel produced via alkaline catalysis and ethylic route on engine performance, and emissions in formulations containing 10 and 20% (m/m) of biodiesel used as additives in base diesel with low sulfur content and cetane ratings of 4
J. Braz. Chem. Soc.. Publicado em: 2017-12
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43. AVANÇOS RECENTES NA HIDROAMINAÇÃO DE COMPOSTOS INSATURADOS
This review presents thermodynamics and kinetics aspects of the hydroamination reaction, recent advancements on this field for non-activated alkenes, alkynes and allenes, employing transition metal catalysis or organocatalysis, including activation by hydrogen bonding or Brønsted acids. Selected syntheses that contain a strategic hydroamination step will be
Quím. Nova. Publicado em: 2017-09
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44. AgAu Nanotubes: Investigating the Effect of Surface Morphologies and Optical Properties over Applications in Catalysis and Photocatalysis
We herein report the preparation of AgAu nanotubes displaying controlled surface morphologies and optical properties by varying the reaction temperature during the galvanic reaction between Ag nanowires and AuCl4-(aq). As the AgAu nanotubes presented similar sizes and compositions, they enabled us to isolate the influence of surface morphology and optical pr
J. Braz. Chem. Soc.. Publicado em: 2017-09
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45. UM PANORAMA DA CATÁLISE NO BRASIL NOS ÚLTIMOS 40 ANOS
In this work, the catalysis area in Brazil is analyzed from several perspectives between 1977 and 2017. The conceptual aspects and the area at world level are briefly introduced. A history of the main organizational initiatives of the area is also presented, highlighting the activities of the Catalysis Division of the Brazilian Chemical Society. An overview
Quím. Nova. Publicado em: 2017-07
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46. Efficient numerical method for solution of boundary value problems with additional conditions
Abstract An efficient numerical method for solution of boundary value problems with additional condition is presented. The approach is based on the shooting method but the procedure of seeking “the proper shot” allows one to satisfy “additional” boundary conditions. General considerations are illustrated by a real example. The computational example c
Braz. J. Chem. Eng.. Publicado em: 2017-07
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47. Intercalation of Molybdate Ions into Ni/Zn Layered Double Hydroxide Salts: Synthesis, Characterization, and Preliminary Catalytic Activity in Methyl Transesterification of Soybean Oil
This study reports the synthesis and characterization of a Ni/Zn layered double hydroxide salt intercalated with acetate ions and the subsequent replacement of the acetate ions with molybdate ions via an ion exchange reaction, conducted at two different pH values. Regardless of the pH employed during the synthesis, the basal spacing in the Ni/Zn layered doub
J. Braz. Chem. Soc.. Publicado em: 2017-07
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48. Ethylene Glycol Electro-Oxidation on Platinum-Free Surfaces: How the Composition of PdRuRh Surfaces Influences the Catalysis
In this work we performed electrochemical (cyclic voltammetry and chronoamperommetry) and spectroelectrochemical studies (in situ Fourier transform infrared (FTIR)) in PdRuRh electrodeposits in acidic media in presence of ethylene glycol (0.5, 1.0 and 2.0 mol L-1). The electrochemical results show that the ethylene glycol oxidation is sensitive to the compos
J. Braz. Chem. Soc.. Publicado em: 2017-06