Olefins
Mostrando 1-12 de 79 artigos, teses e dissertações.
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1. 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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2. ANÁLISE DE AMOSTRAS DE COMBUSTÍVEIS POR FOTOMETRIA, NIR PORTÁTIL E RMN DE 1H - UMA COMPARAÇÃO COM OS RESULTADOS ENCONTRADOS POR TÉCNICAS NORMATIZADAS
It has been recurring adulterations in fuels (such as gasoline, ethanol and diesel), being necessary the exploration of the use of more modern analytical techniques capable of controlling the quality of these fuels, since some regulated tests may be inefficient to detect the adulteration. Among them, it is highlighted proton nuclear magnetic resonance (1H NM
Quím. Nova. Publicado em: 2020-02
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3. SÍNTESE E CARACTERIZAÇÃO DE SURFACTANTES ALQUILFENIL POLIGLICOSÍDICOS A PARTIR DA AMILOSE E ALQUIL FENÓIS EXTRAÍDOS DO LCC NATURAL
The surfactants were synthesized by condensing the obtained oligosaccharides of amylose and alkyl phenols extracted from the natural cashew nut shell liquid (nCNSL). The Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR) data showed aromatic ring bands, glycosidic rings, olefins and paraffins. The Nuclear Overhauser Effect Sp
Quím. Nova. Publicado em: 2016-08
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4. The 1,3-Dipolar Cycloaddition of Nitrile Oxide to Vinylacetic Acid: Computational Study of Transition States Selectivity, Solvent Effects, and Bicyclo Formation
The 1,3-dipolar cycloaddition reaction is a powerful tool for the cycloaddition of nitrile oxides to olefins, and this reaction is of considerable interest to obtain isoxazolines. Density functional theory (DFT) was used to study the 1,3-dipolar cycloaddition reaction mechanism that initially occurs between benzonitrile oxide and vinylacetic acid to yield a
J. Braz. Chem. Soc.. Publicado em: 2016-06
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5. USE OF A LOW-COST TEMPLATE-FREE ZSM-5 FOR ATMOSPHERIC PETROLEUM RESIDUE PYROLYSIS
To understand the physicochemical properties and catalytic activity during the pyrolysis of atmospheric petroleum residue, a template-free ZSM-5 zeolite was synthesized using a direct method without additional seeds or an organic structure director and compared with conventionally synthesized ZSM-5. The crystallinities of the two zeolites were evaluated by X
Quím. Nova. Publicado em: 2016-04
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6. Microwave-Assisted Heck Arylations of Non-Activated N-Acyl-3-pyrrolines with Arenediazonium Tetrafluoroborates
Successful Heck-Matsuda arylations of non-activated olefins applying microwave irradiation as an alternative heating mode are presented. Cleaner reactions were performed with arenediazonium tetrafluoroborates bearing electron-donating and electron-withdrawing groups in good to excellent yields with reaction times reduced from 3.5-18 h to 12-30 min.
J. Braz. Chem. Soc.. Publicado em: 2015-05
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7. Upgrade of Biofuels Obtained from Waste Fish Oil Pyrolysis by Reactive Distillation
Bio-oil is classified as second-generation biofuel and it is produced mainly through the pyrolysis of a waste lignocellulosic biomass base. The application of this product is still very limited, due to some of its chemical characteristics. This paper presents a proposal for the reduction of the acidity of bio-oil obtained from waste fish oil, previously prod
J. Braz. Chem. Soc.. Publicado em: 2015-02
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8. Copolymerization of 1-hexene and 1-dodecene with 1,3-butadiene by a versatate/diisobutylaluminum hydride/t-butyl chloride catalyst system
The aim of this study was to incorporate an alpha-olefin (1-hexene or 1-dodecene) in a high cis polybutadiene chain, using a neodymium versatate/diisobutylaluminum hydride/t-butyl chloride catalyst system. The influence of alpha-olefin on polymerization reaction and polymer characteristics, using different weight ratios of butadiene/α-olefin, was evaluated.
Polímeros. Publicado em: 2014
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9. Palladium-catalyzed arylation of enoates with iodobenzene: stereoselective synthesis of trisubstituted olefins
A reação de Heck entre enoatos de configuração Z e E e o iodobenzeno foi estudada na presença de Pd(OAc)2. A estereoquímica nos adutos formados foi dependente da geometria do enoato (reação estereoespecífica). Os melhores rendimentos foram obtidos a partir de enoatos Z, em acetona, utilizando Ag2CO3 como base. Os principais intermediários catiônic
J. Braz. Chem. Soc.. Publicado em: 2013-03
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10. Geração de mesoporos em zeólitas ZSM-5 e seus efeitos na conversão do etanol em olefinas
Developing mesoporosity in HZSM-5 zeolites is an alternative for improving their catalytic performance on chemical reactions. In this work, alkaline and thermal treatments were used to produce mesoporosity. These treatments increased mesoporous area and volume. They also influenced the acid properties of the samples. Concerning catalytic performance, treatme
Quím. Nova. Publicado em: 2012
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11. ROMP como um método versátil para a obtenção de materiais poliméricos diferenciados
Ring Opening Metathesis Polymerization (ROMP) of cyclic olefins is a powerful transition metal-catalyzed reaction for syntheses of polymers and copolymers. The key feature of this reaction is the [2+2]-cycloaddition mechanism, with retention of the olefinic unsaturation in the polymer chain and occurrence of living polymerization. With the development of met
Química Nova. Publicado em: 2012
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12. Synthesis and characterizaton of molecular sieve SAPO-34 for the production of light olefins from methanol / Síntese e caracterização da peneira molecular SAPO-34 para reação de obtenção de olefinas leves a partir de metanol
A peneira molecular SAPO-34 foi sintetizada pelo método de cristalização hidrotérmica com razões molares de SiO IND. 2/Al IND. 2 O IND. 3 (SAR) de 0,3, 0,5 e 0,7. As amostras foram secas e calcinadas para serem utilizadas na reação catalítica de conversão de metanol para olefinas leves (eteno e propeno). Os sólidos foram caracterizados e foi observ
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 15/12/2011