Basic Catalysis
Mostrando 1-12 de 51 artigos, teses e dissertações.
-
1. IMIDAZOL E CATÁLISE: UM PAR PERFEITO
The imidazole (IMZ) ring presents several chemical properties that turns it into a versatile acid-basic/nucleophilic catalyst. The discovery of the biological properties of histidine (amino acid with IMZ ring) instigates the study of this class of compounds. It is found in nature in several enzymes such as chymotrypsin and RNAses due to these properties. Thi
Quím. Nova. Publicado em: 2021-03
-
2. OTIMIZAÇÃO DO PROCESSO DE TRANSESTERIFICAÇÃO EM DUAS ETAPAS PARA PRODUÇÃO DE BIODIESEL ATRAVÉS DO PLANEJAMENTO EXPERIMENTAL DOEHLERT
In this work, Doehlert experimental design was used to optimize the Transesterification Double Step Process (TDSP) method of methyl soybean oil biodiesel production which starts with a basic catalysis followed by an acidic catalysis. The conversion values were calculated from NMR spectra. Response surface was used to show the results of the interactions betw
Quím. Nova. Publicado em: 2016-04
-
3. FAST GC-FID METHOD FOR MONITORING ACIDIC AND BASIC CATALYTIC TRANSESTERIFICATION REACTIONS IN VEGETABLE OILS TO METHYL ESTER BIODIESEL PREPARATION
A fast gas chromatography with a flame ionisation detector (GC-FID) method for the simultaneous analysis of methyl palmitate (C16:0), stearate (C18:0), oleate (C18:1), linoleate (C18:2) and linolenate (C18:3) in biodiesel samples was proposed. The analysis was conducted in a customised ionic-liquid stationary-phase capillary, SLB-IL 111, with a length of 14
Quím. Nova. Publicado em: 2016-04
-
4. Obtenção de biodiesel por transesterificação em dois estágios e sua caracterização por cromatografia gasosa: óleos e gorduras em laboratório de química orgânica
Methanolic transesterification of oils and fats was carried out in a two steps procedure, under basic and acidic catalysis. Palm, soybean, canola, corn, rice, grapeseed, sunflower, peanut, pequi and olive oils, besides tallow and lard were used as feedstock. Specific gravity, relative viscosity, thin layer chromatography and gas chromatography were used to c
Quím. Nova. Publicado em: 2013
-
5. Catalisadores à base de platina frente a correntes de H2 contendo acetaldeído geradas via reforma do etanol / Platinum-based catalystic in the face of current H2 containing acthaldehyde generated via reforming of ethanol
Due to the greenhouse effect, hydrogen production from bioethanol reforming is a very important subject in heterogeneous catalysis research. Pt based catalysts are employed in H2 purification processes and also as electrocatalysts of PEM (Proton Exchange Membrane) fuel cells. Hydrogen obtained from ethanol reforming may contain acetaldehyde and small amounts
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 23/05/2011
-
6. Influence of the hydrolysis and condensation time on the preparation of hybrid materials
This work describes the hydrolytic sol-gel synthesis of silica particles prepared by a modified Stöber route, using the organofunctionalized alkoxide 3-methacryloxypropyl trimethoxysilane and tetraethylorthosilicate. The silica particles were obtained through basic catalysis from a mixture of precursor alkoxides, water, and isopropyl alcohol. Samples were p
Materials Research. Publicado em: 04/02/2011
-
7. Produção de monoéster via etanólise por hidrotalcitas termoativadas : síntese e caracterização
Among biofuels of the 1st generation, biodiesel stands out for its equivalent features to those of mineral diesel, however less polluting. It can be obtained by transesterification of triglyceride fats or vegetable oils by (m)ethanolysis. Aiming at improving the chemical process, different types of catalysis have been studied: i) homogeneous (acid e.g. H2SO4
Publicado em: 2011
-
8. Produção de biodiesel através de transesterificação in situ de sementes de girassol via catálise homogênea e heterogênea
The objective of this work is to show the results of the in situ transesterification of sunflower seed oil with methanol on basic homogeneous and heterogeneous catalysis for the production of biodiesel. In homogeneous catalysis, the activity of KOH and K2CO3 were evaluated using the same oil:methanol ratio of 1:90. KOH showed to be more active than K2CO3, le
Química Nova. Publicado em: 2010
-
9. Synthesis of biodiesel from transesterification os soybean oil by homogeneous and heterogeneous catalysis / Síntese de biodiesel a partir da transesterificação do óleo de soja por catálises homogênea e heterogênea
Biodiesel is defined as a mono alkyl ester of fatty acids of long chain derived from renewable sources such as vegetable oils and animal fats. Its importance is related to the use as an alternative fuel for diesel cycle engines. The biodiesel could be obtained by the transesterification reaction in which triacylglycerides (oil or grease) react with alcohol i
Publicado em: 2010
-
10. Síntese de biodiesel etílico de girassol utilizando transesterificação alcalina seguido da adição on pot de H2SO4 / Biodiesel synthesis from sunflower oil through alkaline transesterification followed on pot addition of sulfuric acid
In this study, the on pot addition of sulfuric acid was studied in the transesterification process of sunflower oil, using ethanol and methanol, by basic catalysis (NaOH or KOH). That addition implicated in successfully separation of FAEEs from FAMEs/glycerin phases due to soap breaking. The on pot additions yield free fatty acids and salt (Na2SO4 or K2SO4).
Publicado em: 2010
-
11. Síntese e avaliação de sílica tipo M41S contendo cátions CTA em transesterificação catalítica
The investments in the biofuel production have increased a lot in the last years mainly because of smaller damages they cause to the environment in comparison with the derived conventional petroleum fuels. The reaction of biodiesel formation is denominated transesterification and, nowadays that reaction happens in the presence of homogeneous catalyst as the
Publicado em: 2010
-
12. Molecular fluorescence in silica nanoparticles doped with quercetin and rhodamine B / Fluorescência molecular em nanopartículas de sílica marcadas com quercetina e rodamina B
Silica nanospheres doped with quercetin-Al+3 and rhodamine B were synthesized with high size control and morphology, using acid and basic catalysis of tetraethylorthosilicate (TEOS). The nanoparticle diameter obtained was about 200- 300 nm, with higher regularity when synthesized in alkaline media. The Stöbers and core-shell methods were used as preparation
Publicado em: 2009