Speaker: Mª Elena Gálvez Parruca
Chemical and thermochemical biomass processing offer a more sustainable alternative to the conventional synthesis of fuels and chemicals from fossil resources. Moreover, the use lignocellulosic biomass avoids any competition with food industry. Cellulose, hemicellulose and lignin are the three main polymers present in lignocellulose. Out of these three constituents, cellulose is currently the most exploited one. Due to its non-negligible heating value, lignin is often use as a source of process heat, but the examples of its practical chemical valorization are scarce. Still, lignin is the second most abundant natural polymer on our planet and can be considered as an unlimited source of highly functionalized aromatic platform molecules, such as vanillin or syringaldehyde. The work performed at Sorbonne Université aims to develop a reliable process for the oxidative cleavage of lignin by dioxygen that involves unconventional methodologies like ball-milling and sonochemistry. The catalysts used were Keggin-type molybdovanadophosphates (PMoVx), either conventionally synthesized or prepared through an alternative route involving a ball-milling step. In order to facilitate the chemical analysis of the cleavage products, two dimeric lignin models were employed: 2-phenoxyacetophenone and 2-phenoxy-1-phenylethanol. The selective oxidation of these compounds was found to be possible but only at relatively high temperatures (120 °C) and high pressures (5 bar). Ultrasonic intensification was therefore considered, proving that the implosion of cavitation bubbles favors oxygen diffusion within the liquid media, which was found to be one of the most limiting steps of this reaction.
María Elena Gálvez (PhD University of Zaragoza 2005) is Associate Professor at the Faculty of Sciences of Sorbonne Université, and has a renowned experience in the field of energy utilization. She is an expert in thermochemical and thermo-catalytic technologies for hydrogen and fuel synthesis, as well as for CO2 utilization. During her carrier, she has considered different alternative approaches to classical processes, such as plasma intensification, innovative reactor configurations (structured) or the utilization of concentrated solar energy. Particularly, she studies the behaviour of solid materials in these processes and their interaction with the reactive fluid, in order to improve their overall performance. She has published 119 rang A articles in high IF journals and has an h-index of 38 (Scopus).