Examinando por Autor "García, Alicia"

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Diseño de actividades con laboratorios virtuales para fomentar el trabajo autónomo y la adquisición de competencias relacionadas con prácticas de laboratorio experimentales
(2023-11) Cruz del Álamo, Ana; Megía, Pedro; Plaza, Jorge; Casado, Cintia; García, Alicia; Martín, Antonio; Paredes, Beatriz; Villajos, Beatriz; San Martín, Javier; Morales, Gabriel; van Grieken, Rafael; Martínez, Fernando; Molina, Raúl
En este trabajo se muestra el desarrollo de diferentes actividades realizadas con una plataforma online de laboratorios virtuales diseñada por profesores del Departamento de Tecnología Química y Ambiental de la Universidad Rey Juan Carlos. La plataforma incluye 4 prácticas, con una página web para cada una de ellas con diferentes contenidos audiovisuales, entre los que cabe destacar un video del manejo de la instalación experimental y un simulador que reproduce el funcionamiento de la práctica experimental. Durante tres cursos académicos (de 2020/21 a 2022/23), la plataforma se ha utilizado en las asignaturas de Ingeniería de Fluidos y Mecánica de Fluidos de varios grados de la Universidad Rey Juan Carlos como material de apoyo para la realización de las prácticas, como herramienta para complementar las practicas experimentales con actividades adicionales en modo online a través del uso de simuladores virtuales de las prácticas, o como guía para la realización de las prácticas y sistema de evaluación individual. Los estudiantes consideran que la plataforma es un buen complemento para la preparación de las prácticas, mejorando la experiencia posterior en el laboratorio experimental, opinión que es compartida también por los profesores responsables.
Effect of the solvent in the liquid phase rearrangement of 1,2-epoxyoctante over Al-MCM-41 and Al-TS-1 catalysts
(ELSEVIER, 2004) van Grieken, Rafael; Serrano, David P.; Melero, Juan A.; García, Alicia
The role of solvent nature in the liquid phase rearrangement of 1,2-epoxyoctane over Al-TS-1 and Al-MCM-41 catalysts is reported. The main reaction product is the aldehyde, while other rearrangement products, mainly allylic alcohols and diol, are obtained. The solvent polarity influences strongly on the activity and product selectivity. The catalytic activity decreases with the increasing of solvent polarity especially for Al-MCM-41 materials. The use of acetonitrile as solvent yields a low conversion of epoxide as a consequence of its basic character. Formation of bulky by-products was detected when dimethylcarbonate was used as solvent over Al-MCM-41. Toluene displays the best catalytic performance in regards to activity and selectivity towards valuable products, with both Al-TS-1 and Al-MCM-41 catalysts, in comparison to those obtained with more polar solvents.
Efficient Conversion of Glucose to Methyl Lactate with Sn-USY: Retro-aldol Activity Promotion by Controlled Ion Exchange
(ACS, 2022) Jimenez-Martin, Jose M.; Orozco-Saumell, Ana; Hernando, Héctor; Linares, María; Mariscal, Rafael; López Granados, Manuel; García, Alicia; Iglesias, Jose
Sn-USY materials have been prepared through an optimized post-synthetic catalytic metalation procedure. These zeolites displayed, upon ion exchange with alkaline metals, an outstanding activity in the direct transformation of glucose into methyl lactate, yielding more than 70% of the starting glucose as the target product, and an overall combined retro-aldol condensation product yield above 95% in a short reaction time (<4 h). This outstanding catalytic performance is ascribed to the neutralization of Brønsted acid sites, the consequent depression of side reactions, and a higher population of tin open sites in the ion-exchanged Sn-USY zeolites. Reusability tests evidenced some loss of catalytic activity, partially caused by the closing of tin sites, although the use of small amounts of water in the reaction media demonstrated that this deactivation mechanism can be, at least, partially alleviated.
Integrated Environmental and Exergoeconomic Analysis of Biomass-Derived Maleic Anhydride
(Wiley, 2022) Blanco, Jorge; Linares, Maria; López Granados, Manuel; Agirre, Ion; Gandarias, Iñaki; Arias, Pedro Luis; Iglesia, Jose; Moreno, Jovita; García, Alicia
Life cycle analysis and exergy analysis are applied to compare the production of maleic anhydride from different feedstock, both biomass- and petrochemical-derived raw materials, in order to evaluate the sustainability of alternative biorefinery processes to conventional routes. The considered processes involve two options: gas and aqueous phase furfural oxidation with oxygen (air) and hydrogen peroxide as oxidants, respectively, considered as sustainable technologies because of the use of renewable feedstock. Conventional routes, used as benchmarks, include the current production processes using benzene or butane as raw materials. The results show that the aqueous phase process is far from being viable from an energy and environmental point of view due to the high exergy destruction and the use of H2O2 as oxidant (whose production entails important environmental drawbacks). On the contrary, the gas phase oxidation of furfural shows competitive results with petrochemical technologies. Nevertheless, the major environmental drawback of the new furfural-to-maleic anhydride production processes is detected on the environmental profile of the starting raw material. The results suggest that a better environmental footprint for maleic anhydride production in gas phase can be obtained if environmentally friendly furfural production technologies are used at the commercial scale.
Liquid phase isophorone oxide rearrangement over mesoporous Al-MCM-41 materials
(ELSEVIER, 2005) van Grieken, Rafael; Serrano, David P.; Melero, Juan A.; García, Alicia
The rearrangement of isophorone oxide has been investigated over Al-MCM-41 type mesostructured catalysts having different Si/Al molar ratios. The main rearrangement products are the ¿-diketone and the keto aldehyde, whereas the product coming from the decarbonylation of the latter is detected in minor amounts. The textural properties and the number of acid sites of Al-MCM-41 materials influence the extent of isophorone oxide rearrangement reaction. The best catalytic performance in regards to epoxide conversion is obtained for a catalyst having a molar Si/Al ratio around 40 due to a right contribution of acid site concentration and pore size. However, irrespective to the aluminium content of the catalysts and the reaction temperature, the selectivity to the desired keto aldehyde was around 80%. Al-MCM-41 materials are superior catalysts compared to zeolites in terms of both activity and aldehyde selectivity. As a consequence of its large pore size, the use of Al-containing mesostructured materials as catalyst in isophorone oxide rearrangement allows the diffusional problems present in zeolites to be avoided.
Liquid phase rearrangement of long straight-chain epoxides over amorphous, mesostructured and zeolitic catalysts
(ELSEVIER, 2004) Serrano, David P.; van Grieken, Rafael; Melero, Juan Antonio; García, Alicia
A variety of materials with different structural features and acid properties, including amorphous, mesostructured and zeolitic catalysts have been tested in the liquid-phase rearrangement of 1,2-epoxyoctane. The structure and acid strength of the catalysts influence strongly on the activity and product selectivity. The main rearrangement products are the aldehyde, allylic alcohols and diol. Acid sites in the amorphous materials show a poor catalytic activity. Al-TS-1 and Al-Ti-beta, zeolites with medium aluminium content, lead to significant activities and selectivities towards both the aldehyde and the octenols in comparison to those obtained with other zeolitic materials tested. Aluminium-containing mesostructured materials present much higher activities than amorphous and zeolitic catalysts. Al-MCM-41 synthesized by a sol-gel method at room temperature yielded selectivities to octaldehyde and octen-1ols of 40.6% and 44.7%, respectively with a high catalyst activity (TOF of ca. 30.5).
Production of Methyl Lactate with Sn-USY and Sn-β: Insights into Real Hemicellulose Valorization
(American Chemical Society, 2024-02-19) Jiménez-Martin, José M.; El Tawil-Lucas, Miriam; Montaña, Maia; Linares, María; Osatiashtiani, Amin; Vila, Francisco; Martín Alonso, David; Moreno, Jovita; García, Alicia; Iglesias, José
Potassium exchanged Sn-β and Sn-USY zeolites have been tested for the transformation of various aldoses (hexoses and pentoses), exhibiting outstanding catalytic activity and selectivity toward methyl lactate. Insights into the transformation pathways using reaction intermediates─dihydroxyacetone and glycolaldehyde─as substrates revealed a very high catalytic proficiency of both zeolites in aldol and retro-aldol reactions, showcasing their ability to convert small sugars into large sugars, and vice versa. This feature makes the studied Sn-zeolites outstanding catalysts for the transformation of a wide variety of sugars into a limited range of commercially valuable alkyl lactates and derivatives. [K]Sn-β proved to be superior to [K]Sn-USY in terms of shape selectivity, exerting tight control on the distribution of produced α-hydroxy methyl esters. This shape selectivity was evident in the transformation of several complex sugar mixtures emulating different hemicelluloses─sugar cane bagasse, Scots pine, and white birch─that, despite showing very different sugar compositions, were almost exclusively converted into methyl lactate and methyl vinyl glycolate in very similar proportions. Moreover, the conversion of a real hemicellulose hydrolysate obtained from Scots pine through a simple GVL-based organosolv process confirmed the high activity and selectivity of [K]Sn-β in the studied transformation, opening new pathways for the chemical valorization of this plentiful, but underutilized, sugar feedstock.