Examinando por Autor "Ventura, María"

Mostrando 1 - 4 de 4

Carbonaceous materials from a petrol primary oily sludge: Synthesis and catalytic performance in the wet air oxidation of a spent caustic effluent
(Elsevier, 2024-08) Jerez, Sara; Ventura, María; Martínez, Fernando; Pariente, María Isabel; Melero, Juan Antonio
Oil refineries produce annually large quantities of oily sludge and non-biodegradable wastewater during petroleum refining that require adequate management to minimize its environmental impact. The fraction solid of the oily sludge accounts for 25 wt% and without treatment for their valorization. This work is focused on the valorization of these solid particles through their transformation into porous materials with enhanced properties and with potential application in the catalytic wet air oxidation (CWAO) of a non-biodegradable spent caustic refinery wastewater. Hence, dealing with the valorization and treatment of both refinery wastes in a circular approach aligned with the petrol refinery transformations by 2050. The obtained oily sludge carbonaceous materials showed improved surface area (260–762 m2/g) and a high Fe content. The good catalytic performance of these materials in CWAO processes has been attributed to the simultaneous presence of surface basic sites and iron species. Those materials with higher content of Fe and basic sites yielded the highest degradation of organic compounds present in the spent caustic refinery wastewater. In particular, the best-performing material ACT-NP 1.1 (non-preoxidated and thermically treated with 1:1 mass ratio KOH:solid) showed a chemical oxygen demand (COD) removal of 60 % after 3 h of reaction and with a higher degradation rate than that achieved with thermal oxidation without catalyst (WAO) and that using an iron-free commercial activated carbon. Moreover, the biodegradability of the treated wastewater increased up to 80% (from ca. 31% initially of the untreated effluent). Finally, this material was reused up to three catalytic cycles without losing metal species and keeping the catalytic performance
Heterogeneous catalysts for the selective aerobic oxidation of 5-hydroxymethylfurfural to added value products in water
(Elsevier, 2018) Ventura, María; Dibenedetto, Angela; Aresta, Michele
This review presents the state of the art of the aerobic selective oxidation of 5-hydroxymetylfurfural (5-HMF) with heterogeneous catalysts in water, for the preparation of added value products. Aspects such as kind of metals used for making the catalysts and external additives will be examined. The paper is divided into four main parts each dealing with a specific product obtained from 5-HMF: (a) 2,5-diformylfuran (DFF), (b) 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), (c) 5-formyl-2-furancarboxylic acid (FFCA), (d) 2,5-furandicarboxylic acid (FDCA).
MgO-based catalysts for selective delignification of lignocellulosic waste and carboxylic acids production under mild hydrothermal conditions
(Elsevier, 2025-08) Vidal, Nora; Ventura, María; Orfila, María; Martínez, Fernando; Melero, Juan Antonio
Lignocellulosic biomass offers a sustainable alternative to traditional raw materials. However, its complex structure, and particularly the presence of lignin, presents a significant challenge for its conversion into valuable products. This study explores the catalytic performance of magnesium oxide (MgO) based materials for the selective delignification of lignocellulosic waste and concomitant carboxylic acids production. Different MgO samples have been synthesized through various synthetical methods with the purpose of promoting the selective delignification of a lignocellulose waste while minimizing the degradation of other polymers (cellulose and hemicellulose). The resultant lignin-free holocellulose solid after selective depolymerization might be used in subsequent fermentation processes. The catalytic results demonstrated that MgO synthesized by a sol-gel method exhibited the highest catalytic activity, achieving ca. 90 % lignin conversion with minimal degradation of cellulose and hemicellulose and outstanding production of carboxylic acids (ca. 30 % of the carbon of the degraded polymers was converted into carboxylic acids). The high concentration of medium-strength base sites combined with significant macroporosity are crucial for enhancing the catalytic performance of MgO-based catalysts. Importantly, these results were achieved under mild conditions (120 ◦ C) using water as a solvent and without addition of external oxidant agents. Furthermore, the study observed a significant production of valuable (di) carboxylic acids, such as fumaric acid during the depolymerization process over optimized MgO catalyst. This research provides valuable insights into the potential of MgO as a sustainable catalyst for the selective conversion of lignin present in lignocellulosic biomass into valuable chemicals and biofuels.
Synthesis and structural characterization of novel tetranuclear organotitanoxane derivatives
(Royal Society of Chemistry, 2011-04-21) Ventura, María; Ramirez de Arellano, Carmen; Gómez Mosquera, Marta Elena; Jiménez, Gerardo; Cuenca, Tomás
Synthesis of the novel titanoxane compounds, [(TiCl)(TiOH){(Ti)[μ-(η5-C5Me4SiMe2O-κO)]2(μ-O)}2(μ-O)] (4) and [{Ti[μ-(η5-C5Me4SiMe2O-κO)](μ-O)}4] (5) by controlled reaction of the dinuclear titanium oxo complex [{Ti{μ-(η5-C5Me4SiMe2O-κO)}Cl]2(μ-O)] (1) with 2 equiv of LiOH is reported. Complex 4 is innovative and remarkable. It is one of the rare known examples of tetranuclear stable terminal hydroxo titanium complexes, with an open-chained structure, which coincides with the transient metal monohydroxo proposed in the stepwise pathway employed to justify the formation of the hexanuclear complex [{Ti[μ-(η5-C5Me4SiMe2O-κO)](μ-O)}6] (3) from 1. 1H DOSY experiments were used to characterize complex 4. In addition, the structures of compound 5 and of precursor 1 were determined by single-crystal X-ray diffraction studies.