Palladium
Mostrando 13-24 de 193 artigos, teses e dissertações.
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13. MORE ACTIVE AND SULFUR RESISTANT BIMETALLIC Pd-Ni CATALYSTS
The influence of the kind of metal precursor and the sequence of impregnation on the properties of Pd-Ni catalysts was evaluated during the test reaction of selective hydrogenation of styrene to ethylbenzene by means of physicochemical characterization. The focus was put on the final hydrogenating activity and the resistance to deactivation by sulfided compo
Quím. Nova. Publicado em: 2018-02
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14. Influence of Nanoxides on Diffusivity and Solubility of Hydrogen in Pd-based alloys
The hydrogen interaction in palladium alloys with addition of Ce, Zr and Y was studied. These alloys are produced by arc-melting and then cold rolled into thin foils. Heat treatment at 800ºC for 24h in air atmosphere is applied to induce internal oxidation. Hydrogen permeation tests and TDS (Thermal Desorption Spectroscopy) are carried out to evaluate hydro
Mat. Res.. Publicado em: 11/01/2018
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15. Cellulose Oxidation and the Use of Carboxyl Cellulose Metal Complexes in Heterogeneous Catalytic Systems to Promote Suzuki-Miyaura Coupling and C-O Bond Formation Reaction
This work shows the modification of microcrystalline cellulose by the selective oxidation of primary hydroxyl groups to carboxylate groups by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated system and its application as a heterogeneous ligand by ionic exchange with catalytic metals ions such as palladium, nickel and copper. Afterwards is desc
J. Braz. Chem. Soc.. Publicado em: 2017-11
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16. DESEMPENHO DO ELETRODO DE FILME DE PALÁDIO NA DETERMINAÇÃO DE TÁLIO E CHUMBO EM AMOSTRAS DE ÁGUAS NATURAIS POR VOLTAMETRIA DE REDISSOLUÇÃO ANÓDICA COM PULSO DIFERENCIAL
The use of a palladium film electrode (PdFE) as an alternative electrode for the determination of thallium (Tl+) and lead (Pb2+) in water samples by anodic stripping voltammetry is proposed. Preliminary studies of the influence of the substrate were performed on the electrochemical behavior of PdFE prepared ex situ. Using a silver solid amalgam electrode as
Quím. Nova. Publicado em: 2017-09
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17. Impact of Ni Substitution on Structural, Electrical and Thermoelectrical Properties of Zinc Alluminium Chromites Synthesized by sol-gel Route and their Photocatalytic Investigation
Nanostructured nickel substituted zinc alluminium chromites (Zn1-xNixAlCrO4, where, x= 0.0, 0.25, 0.50, 0.75, 1.0) were prepared by simple, cost effective, sol-gel autocombustion method. Temperature of phase formation was analyzed by thermogravimetric and differential thermal analysis (TGA/DTA). Crystallographic studies of all the samples show formation of s
Mat. Res.. Publicado em: 17/08/2017
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18. Antitubercular Activity Increase in Labdane Diterpenes from Copaifera Oleoresin through Structural Modification
The labdane diterpenes copalic acid, 3β-acetoxy-copalic acid, 3β-hydroxy-copalic acid and ent-agathic acid were isolated from Copaifera langsdorffii oleoresin. These four compounds were submitted to structural modifications by reduction with hydrogen/palladium, esterification with diazomethane, esterification with methanol/sulfuric acid and conversion into
J. Braz. Chem. Soc.. Publicado em: 2017-06
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19. The Effect of Gamma-Al2O3 Support on the NO Adsorption on Pd4 Cluster
The effect of γ-Al2O3 support on the NO adsorption on Pd4 clusters was investigated by means of density functional theory (DFT) calculations. Pd4 adsorbed on γ-Al2O3 (represented by a Al14O24H6 cluster) changes its preferential geometry from tetrahedral to a distorted planar structure. The alumina support promotes a higher dispersion in the palladium catal
J. Braz. Chem. Soc.. Publicado em: 2016-11
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20. MODELING STYRENE HYDROGENATION KINETICS USING PALLADIUM CATALYSTS
Abstract The high octane number of pyrolysis gasoline (PYGAS) explains its insertion in the gasoline pool. However, its use is troublesome due to the presence of gum-forming chemicals which, in turn, can be removed via hydrogenation. The use of Langmuir-Hinshelwood kinetic models was evaluated for hydrogenation of styrene, a typical gum monomer, using Pd/9%N
Braz. J. Chem. Eng.. Publicado em: 2016-09
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21. CHARACTERISATION OF ASYMMETRIC ALUMINA HOLLOW FIBRES: APPLICATION FOR HYDROGEN PERMEATION IN COMPOSITE MEMBRANES
Abstract Asymmetric alumina hollow fibres produced by the phase inversion/sintering method present advantages in that high area/volume ratios and low mass transfer resistances are achieved due to the geometric configuration and the pore size distribution, respectively. Here we characterise hollow fibres that were prepared with different internal coagulants a
Braz. J. Chem. Eng.. Publicado em: 2016-09
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22. SÍNTESES TOTAIS NO BRASIL EMPREGANDO ACOPLAMENTOS CRUZADOS MEDIADOS POR PALÁDIO
This article aims to show the selected total syntheses of organic compounds conducted by Brazilian researchers, performed in Brazil, which have employed a palladium catalyzed cross-coupling reaction as key step. We intended to thus create an account, although restricted to the use of palladium, showing the evolution and current state of art of Synthetic Orga
Quím. Nova. Publicado em: 2016-08
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23. FLUOROUS SUPPORTED SYNTHESIS OF PYRAZOLONE DERIVATIVES FROM ALLYLIC ALCOHOLS USING A PALLADIUM-CATALYZED STRATEGY
Ten substituted pyrazolone derivatives were easily synthesized from perfluorinated allylic alcohols, via a straightforward two steps reaction involving a Heck-coupling/isomerization reaction and subsequent condensation of hydrazines. This fluorous supported methodology, that combines a cyclo-release approach and F-SPE purification allows for the obtaining of
Quím. Nova. Publicado em: 2016-08
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24. Pd-Impregnated activated carbon and treatment acid to remove sulfur and nitrogen from diesel
ABSTRACT Removal of sulfur and nitrogen compounds from national commercial diesel through adsorption onto activated carbon was studied. Brazilian commercial activated carbon samples (AC) were modified by acid oxidation and, alternatively, were impregnated with palladium chloride. Modified carbon samples showed a significant increase in the quantity of acid s
Matéria (Rio J.). Publicado em: 2016-06