Sample records for CATALISIS HETEROGENEA (heterogeneous catalysis)
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1

Producción de biodiesel de aceite crudo de palma mediante catálisis heterogénea/ Production of crude palm oil biodiesel by heterogeneous catalysis

Cardeño, Fernando; Ríos, Luis; Franco, Alexander
2010-02-01

Resumen en español Se estudió la producción de biodiesel de aceite crudo de palma mediante el uso de catalizadores heterogéneos ácidos y básicos para las etapas de preesterificación y transesterificación respectivamente. La pre-esterificación es necesaria para aceites con una acidez superior al 4% de ácidos grasos libres, ya que se evitan los problemas asociados con la formación de jabones. En ambas reacciones las variables analizadas fueron el tipo de catalizador, la temperatura (mas) y el tiempo. Se analizó la conversión del aceite a metilésteres usando cromatografía gaseosa y la estabilidad de los catalizadores mediante su reutilización. En la etapa de pre-esterificación se encontró que catalizadores ácidos del tipo resinas de poliestireno sulfonadas presentan conversiones superiores al 87% estabilidad para la esterificación de los ácidos grasos libres. Para la transesterificación se estudiaron como catalizadores heterogéneos, el carbonato de potasio libre y soportado en una matriz polimérica, obteniéndose con ambos conversiones superiores a 95 % de biodiesel; con el uso del soporte polimérico se disminuyó la velocidad de disolución de carbonato de potasio, permitiendo su reutilización hasta 10 reutilizaciones. Resumen en inglés The production of crude palm oil biodiesel was studied by using acid and basic heterogeneous catalysts by pre-esterification and transesterification steps, respectively. Pre-esterification step is necessary for high free fatty acid content oils because problems associated with soap formation are avoided. In both reactions the variables analyzed were catalyst type, temperature and time. Conversion of oil to methyl ester was analyzed using gas chromatography and the stabili (mas) ty of catalysts by means of reutilization. In the pre-esterification step it was found that acid catalysts type sulfonated polystyrene resin show high conversion and stability for the esterification of free fatty acids. Heterogeneous catalysts both free and supported in a polymeric matrix potassium carbonate were studied for transesterification. High conversions to biodiesel were obtained. Using the polymeric matrix decreased the potassium carbonate dissolution rate, allowing its reutilization.

Scientific Electronic Library Online (Spanish)

2

Producción de Sílice Mesoporosa Empleando Monoestearato de Glicerol como Porógeno Oleoquímico/ Production of Mesoporous Silica using Glycerol Monostearate as Oleochemical Porogen

Peña, Juan D; Cardona, Eliana M; Marín, Juan M; Rios, Luis A
2009-01-01

Resumen en español El presente trabajo describe el desarrollo de una novedosa síntesis de sílices mesoporosas basada en un mecanismo en dos etapas en medio ácido (pH = 2), empleando materias primas renovables. La primera etapa consistió en la formación de micelas híbridas estables, producto de la interacción entre silicatos y el agente porógeno, y la segunda en la policondensación de silicatos para formar sílice. Se evaluaron dos fuentes de silicio: tetraetilortosilicato (TEOS) y (mas) metasilicato de sodio (MSiNa). Como porógeno oleoquímico se usó monoestearato de glicerol y como iniciador de la reacción de policondensación se usó fluoruro de sodio (NaF). Las sílices obtenidas con las mejores propiedades texturales, poseen características superficiales interesantes para un potencial aplicación en catálisis heterogénea, con área superficial BET de 727.4 m²/g, volumen total de poros de 0.50 cm³/g y distribución de tamaños de poro alrededor de 46.2 Å Resumen en inglés This paper describes the development of a novel synthesis of mesoporous silica based on a two-step process, in acidic media (pH = 2), using renewable raw materials. The first stage was the formation of stable hybrid micelles, product of the interaction between the porogen and silicates, and the second was the polycondensation of silicates to produce silica. Two sources of silicon were used: tetraethylortosilicate (TEOS) and sodium metasilicate (MSiNa). Glycerol monosteara (mas) te was used as oleochemical porogen and sodium fluoride was used as initiator for the reaction of condensation of silica. The silica obtained with the best textural properties have interesting surface characteristics for potential applications in heterogeneous catalysis, with BET surface area of 727.4 m² / g, total volume of pores of 0.50 cm³/g and pore size distribution of about 46.2 Å

Scientific Electronic Library Online (Spanish)

3

Variables de operación en el proceso de transesterificación de aceites vegetales: una revisión - catálisis química/ Operations variables in the transesterification process of vegetable oil: a review - chemical catalysis

Rojas González, Andrés Felipe; Girón Gallego, Erika; Torres Castañeda, Harlen Gerardo
2009-12-01

Resumen en español Este artículo presenta los resultados de una revisión bibliográfica de los efectos de las variables de operación sobre el rendimiento en la transesterificación química de aceites vegetales. Las variables estudiadas fueron: temperatura y tiempo de reacción, concentración molar alcohol:aceite vegetal, tipo de alcohol, tipo de catalizador, concentración de catalizador, intensidad del mezclado, y concentración de ácidos grasos libre y humedad. También se reporta q (mas) ue este proceso se ha llevado a cabo empleando catalizadores ácidos y básicos, a través de procesos catalíticos homogéneos y heterogéneos, para una amplia variedad de aceites. Se encontró que el rendimiento de la reacción se incrementa cuando la temperatura y el tiempo de reacción aumenta, pero disminuye a bajas concentraciones de catalizador ( 1% w/w) y humedad (> 3% w/w) en el aceite. Resumen en inglés This article describes the results of a bibliographic review of the effects of operation conditions on process yield in the chemical transesterification of vegetable oil. The parameters studied were: temperature and time reaction, alcohol:oil molar ratio, catalyst and alcohol type, catalyst concentration, mixed intensity and free fatty acid and water concentration. It also reports that this process has been carried out with basic and acid catalysts using homogeneous and h (mas) eterogeneous catalytic processes for a wide variety of oils. It was found that reaction yield increased when temperature and time reaction increased; however this parameter decreased at low catalyst concentration ( 1% w/w) and water (> 3% w/w) concentration in oil.

Scientific Electronic Library Online (Spanish)

4

Structural changes in polyethylene terephthalate (PET) wastes materials caused by pyrolysis and CO2 activation

Parra Soto, José Bernardo; Ovín Ania, M.ª Concepción; Arenillas de la Puente, Ana; Rubiera González, Fernando

11 pages. | For ecological reasons, there is an increasing demand for recycling polyethylene terephthalate (PET) wastes in developed countries. Although one potential application might be its utilisation for the production of activated carbons, the behaviour of these wastes when subjected to differe...

DRIVER (Spanish)

5

Structural changes in polyethylene terephthalate (PET) wastes materials caused by pyrolysis and CO2 activation

Parra Soto, José Bernardo; Ovín Ania, M.ª Concepción; Arenillas de la Puente, Ana; Rubiera González, Fernando; Pis Martínez, José Juan; Palacios, J. M.
2006-06-01

Digital.CSIC (Spain)

8

Role of electron-hole pair excitations in the dissociative adsorption of diatomic molecules on metal surfaces

Juaristi Oliden, Joseba Iñaki; Alducin Ochoa, Maite; Díez Muiño, Ricardo; Busnengo, Heriberto Fabio

PACS nts.: 82.65.+r, 34.35.+a, 68.49.Df, 82.20.Kh. | We quantitatively evaluate the contribution of electron-hole pair excitations to the reactive dynamics of H2 on Cu(110) and N2 on W(110), including the six dimensionality of the process in the entire calculation. The interaction energy between mol...

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9

Role of electron-hole pair excitations in the dissociative adsorption of diatomic molecules on metal surfaces

Juaristi Oliden, Joseba Iñaki; Alducin Ochoa, Maite; Díez Muiño, Ricardo; Busnengo, Heriberto Fabio; Salin, Antoine
2008-03-20

Digital.CSIC (Spain)

10

Photocatalytic-based strategies for H2S elimination

Portela, R.; Suárez, S.; Rasmussen, S.B.
2010-01-01

Digital.CSIC (Spain)

11

On the mechanism of reactive adsorption of dibenzothiophene on organic waste derived carbons

Ovín Ania, M.ª Concepción; Parra Soto, José Bernardo; Arenillas de la Puente, Ana; Rubiera González, Fernando; Bandosz, T. J.; Pis Martínez, José Juan
2007-04-30

Digital.CSIC (Spain)

12

Nitrate removal using natural clays modified by acid thermoactivation

Mena-Durán, C. J.; Sun Kou, M. R.; López, T.; Azamar-Barrios, J. A.; Aguilar, D. H.; Domínguez, M. I.; Odriozola Gordon, José Antonio
2007-01-05

Digital.CSIC (Spain)

13

Nickel nanoparticles in hydrogen-transfer reductions: characterisation and nature of the catalyst

Alonso Valdés, Francisco; Riente Paiva, Paola; Sirvent Pérez, Juan Alberto; Yus Astiz, Miguel

Nickel nanoparticles, readily prepared by reduction of nickel(II) chloride with lithium and a catalytic amount of DTBB, have been used in the transfer hydrogenation of carbonyl compounds and have been fully characterised by different means. The reaction rate of the transfer hydrogenation was found t...

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14

New Rare-earth Coordination Polymers as Multifunctional Materials

Monge Bravo, M. Angeles; Snejko, Natalia; Gándara Barragán, Felipe
2010-01-01

Digital.CSIC (Spain)

15

Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst

Valdés-Solís Iglesias, Teresa; Valle Vigón, Patricia; Álvarez García, Sonia; Marbán Calzón, Gregorio

6 pages, 5 figures. -- Printed version published Dec 2007. -- Correction published in Catalysis Communications 9(15): 2621 (2008), http://hdl.handle.net/10261/11596 | Spinel ferrite MnFe2O4 nanoparticles were synthesized by means of a nanocasting technique using a low-cost mesoporous silica gel as a...

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16

Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst

Valdés-Solís Iglesias, Teresa; Valle Vigón, Patricia; Álvarez García, Sonia; Marbán Calzón, Gregorio; Fuertes Arias, Antonio Benito
2007-04-10

Digital.CSIC (Spain)

17

Highly efficient deep desulfurization of fuels by chemical oxidation

Capel Sánchez, María del Carmen; Perez-Presas, P.; Campos Martín, Jose Miguel; Fierro, Jose L. G.
2010-01-01

Digital.CSIC (Spain)

18

Electron transfer to sulfides and disulfides: intrinsic barriers and relationship between heterogeneous and homogeneous electron-transfer kinetics

Meneses, Ana Belén; Antonello, Sabrina; Arévalo, Maria Carmen; González Martín, Concepción C.; Sharma, Jadab; Wallette, Andrea N.; Workentin, Mark S.; Maran, Flavio
2007-07-06

Digital.CSIC (Spain)

19

Efecto de la naturaleza del precursor sobre las caracteristicas de las nanoparticulas de SnO2 sintetizadas/ Effect of the precursor's nature on characteristics of synthesized SnO2 nanoparticles

Ararat-Ibarguen, Carlos E.; Montenegro, Alejandra; Rodríguez-Páez, Jorge E.; Urresta Aragón, Julián
2007-01-01

Resumen en inglés Tin oxide (SnO2) is widely used in industry as raw material for electronic devices, plating of different types of materials, for dyes and pigments, for electroplating, heterogeneous catalysis, etc. In this work SnO2 was obtained by a controlled precipitation method with special attention to the effects the tin precursor has on the microstructure of the final product. The most appropriate pH for obtaining SnO2 with the rutile structure as the main phase is 6.25 for SnCl2 a (mas) nd 6.40 for SnSO4. After heat treatment at 600 °C, particles of nanometric order (~10 - 30 nm approx) were obtained. The characterization of the solid phase was made by X-ray diffraction (XRD), thermal analysis (DTA/TG), transmission electron microscopy (TEM) and Fourier transformed infrared spectroscopy (FTIR).

Scientific Electronic Library Online (Spanish)

20

Corrigendum to “Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst” [Catal. Comm. 8 (2007) 2037–2042]

Valdés-Solís Iglesias, Teresa; Valle Vigón, Patricia; Álvarez García, Sonia; Marbán Calzón, Gregorio

1 page. -- Printed version published Sep 2008. -- Correction to: "Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst" [Catalysis Communications 8(12): 2037-2042 (2007)], http://digital.csic.es/handle/10261/11594 | The units of the reaction rate...

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21

Corrigendum to “Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst” [Catal. Comm. 8 (2007) 2037–2042]

Valdés-Solís Iglesias, Teresa; Valle Vigón, Patricia; Álvarez García, Sonia; Marbán Calzón, Gregorio; Fuertes Arias, Antonio Benito
2008-08-05

Digital.CSIC (Spain)

23

A Zeolite Structure (ITQ-13) with Three Sets of Medium-Pore Crossing Channels Formed by 9- and 10-Rings

Corma, Avelino; Puche, Marta; Rey García, Fernando; Sankar, Gopinathan; Teat, Simon J.

Final full-text version of the paper available at Angewandte Chemie International Edition website: http://dx.doi.org/10.1002/anie.200390304.-- Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2003/z50514_s.pdf or from the author.-- Corrig...

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24

A Zeolite Structure (ITQ-13) with Three Sets of Medium-Pore Crossing Channels Formed by 9- and 10-Rings

Corma, Avelino; Puche, Marta; Rey García, Fernando; Sankar, Gopinathan; Teat, Simon J.
2003-03-10

Digital.CSIC (Spain)