Navegando por Autor "Bernardo-Gusmão, Katia"
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Artigo Heterogeneous complexes of nickel MCM-41 with β-diimine ligands: applications in olefin oligomerization(Elsevier, 2015-03) Rossetto, Enéderson; Nicola, Bruna Pes; Souza, Roberto Fernando de; Bernardo-Gusmão, Katia; Pergher, Sibele Berenice CastellãThe β-diimine ligands 2-(phenyl)amine-4-(phenyl)imine-2-pentene and 2-(2,6-dimethylphenyl)amine-4-(2,6-dimethylphenyl)imine-2-pentene were combined with the alkoxysilane group chloropropyltrimethoxysilane (CPTMS) and covalently anchored to a mesoporous MCM-41 support; they were ordered via interactions with the silanols of the silica matrix and complexed with nickel. The complexes were synthesized for use in ethylene and propylene oligomerization and for comparing the results of homogeneous and heterogeneous systems. The support was first synthesized, calcined, anchored to the ligand, and then, complexed with nickel. These materials were characterized using various techniques, such as 1H, 13C, and 29Si NMR, small angle XRD, thermogravimetric analysis, adsorption isotherms, transmission electron microscopy, and flame atomic absorption spectroscopy, to confirm the success of the synthesis. Both homogeneous and heterogeneous complexes are active and selective for the reactions of ethylene and propylene oligomerizationArtigo Nickel oligomerization catalysts heterogenized on zeolites obtained using ionic liquids as templates(Elsevier, 2010-02-01) Mignoni, Marcelo Luis; Souza, Michèle Oberson de; Pergher, Sibele Berenice Castellã; Souza, Roberto Fernando de; Bernardo-Gusmão, KatiaSynthesis of zeolites using 1-butyl-3-methylimidazolium chloride (BMI.Cl) as a template yields highly crystalline materials after a 3-day reaction time. SEM micrographs of material obtained with a Si/Al molar ratio of 50 showed formation of very regular microspherical agglomerates with approximate diameters of 30 μm composed of ZSM-5 crystallites with 3–5 μm long edges. The regular format of these crystallites has been attributed to the formation of micellar aggregates due to the ionic liquid. Decreasing the Si/Al molar ratio to 20 reduces the diameter of the microspheres to less than 1 μm. The ZSM-5 zeolites show a specific area of 384 m2 g−1 and a microporous volume of 0.10 cm3 g−1, and the β-zeolite, obtained after 7 days of crystallization, shows a specific area of 418 m2 g−1 and a microporous volume of 0.11 cm3 g−1. The β-zeolite was used as support for a nickel β-diimine complex and the system used in ethylene catalytic oligomerization reactions.