Matériaux hybrides mésoporeux en catalyse (du matériau support au système catalytique)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Evaluating the sustainable use of resources: Session in LCM2023

International audienceResources are used for their instrumental value, i.e. for their utility in the anthroposphere. Given the volume of resources consumed each year in various industrial sectors in a globalized market as well as the non-renewable nature of abiotic resources, their sustainable use might be compromised. Many approaches have been developed and applied to evaluate the sustainable use of resources. Among them, resource criticality aims at assessing the risks associated with resource supply for a given market. Methodological developments have been proposed for the last 10 years to evaluate the criticality of resources and integrate it into broader sustainability tools. In parallel, LCA captures the intrinsic environmental impacts of resource use from their extraction to their multiple life cycles, however, discussion on how to quantify resource use and efficiency on the safeguard subject for resources and its consideration in LCA are still ongoing. These discussions include concepts such as resource ‘value’, ‘accessibility’, ‘quality’ or ‘functionality’ without consensual definition of these concepts and the way to assess/quantify them. These concepts are moreover relevant both in the LCA framework and in the measure of resource efficiency towards a circular economy. At the crossroads between sustainability and circular economy, this session welcomes new developments and approaches exploring how to assess the sustainable use of resources. Industrial perspectives on how to evaluate and ensure the sustainable supply and use of resources are also welcomed

Hybrid bidentate ligand for functional recognition: an application to regioselective C=C double bond hydrogenation

3 pagesRegioselectivity increases in C=C double bond hydrogenation could be obtained for Lewis basic substrates on a Lewis acidic support by using a rhodium complex supported on a mesoporous solid

Organic reactivity of alcohols in superheated aqueous salt solutions: an overview

The low dielec. const. and high self-dissocn. const. of water in a temp. range between 150 and 250 °C make it a very appealing solvent for synthesis. Surprisingly, while org. chem. in water at low temp. or around its crit. point has been investigated in detail, very little seems to be known about the behavior of org. mols. under hydrothermal conditions. The present work thus aims at shedding some light on this field. As a start, we decided to investigate the reactions in which alcs. can undergo in water in the above-mentioned temp. range. Knowing that very strong salt effects on org. reactions have already been obsd. in super crit. water, the impact of salt on the outcome of our tests was also investigated in detail

Simultaneous lanthanides and surfactants micelles removal from aqueous outflows by complexation and sol–gel chemistry

International audienc

High-Surface-Area SiO2-ZrO2 Mixed Oxides as Catalysts for the Friedel-Crafts-Type Alkylation of Arenes with Alcohols and Tandem Cyclopropanation Reactions

International audienceThe catalytic activity of SiO2-ZrO2 mixed oxides was studied for the Friedel-Crafts-alkylation reaction between anisole and benzylic or allylic alcohols. In particular, the influence of Zr content on the catalytic activity was studied. The catalyst with the lowest Zr content (5 mol% ZrO2) showed the highest activity with high selectivity for the alkylated product and good recyclability. We used this catalyst in the reaction of 1-phenyl-1- ethanol with toluene and xylene. We also studied the possibility of a tandem process that involved a Friedel-Crafts alkylation and the subsequent trans-hydrogenation of trans-1,3-diphenyl- 2-propen-1-ol for the synthesis of substituted cyclopropanes

Efficiency enhancement of decontamination gels by a superabsorbent polymer

International audiencePhysical gels have been studied as an advantageous alternative to traditional decontamination techniques, which most often rely on the use of surfactant solutions. Such physical gels consist of colloidal particles suspended in a decontaminating solution. They can be sprayed over the surfaces to be treated, where they dry and form solid disposable residues. In order to improve their efficiency, the formulation of gels containing superabsorbents (such as sodium polyacrylate) has recently been suggested. But the mechanism accounting for the observed efficiency increase has not yet been investigated. These additives have a large swelling potential in aqueous media and the amount of adsorbed water depends on the presence of salts in the medium. We anticipated that specific ion effects on the swelling behavior of superabsorbent polymers were the driving force of efficiency enhancement and confirmed this assumption by rheology and in situ tests

Surface Diels-Alder Reactions as an Effective Method to Synthesize Functional Carbon Materials

International audienceThe post-synthesis chemical modification of various porous carbon materials with unsaturated organic compounds is reported. By this method, amine, alcohol, carboxylate, and sulfonic acid functional groups can be easily incorporated into the materials. Different carbonaceous materials with surface areas ranging from 240 to 1500 m2 g 1 and pore sizes between 3.0 and 7.0 nm have been studied. The resulting materials were analyzed by elemental analysis, nitrogen sorption, FTIR spectroscopy, zeta-potential measurements, thermogravimetric analysis, photoelectron spectroscopy, and small-angle X-ray scattering. These analyses indicated that the degree of functionalization is dependent on the nature of the dienophile (reactivity, steric hindrance) and the porosity of the carbon material. As possible applications, the functionalized carbonaceous materials were studied as catalysts in the Knoevenagel reaction and as adsorbents for Pb2+ from aqueous solution

A topping gel for the treatment of nuclear contaminated small items

International audienceNuclear decontamination is a key aspect of the decommissioning of facilities, can today be carried out using gelled reagents sprayed over contaminated surfaces (tens of square meters) and allows easy radionuclide retrieval. Wide ranges of formulations have been developed in our laboratory to treat several materials. The gels are formulated by adding colloidal silica particles to a reactive solution; they dry and form solid residues that are easily collected and directly conditioned. Dissemination hazards are reduced and no liquid effluent is generated or released. In order to adapt the process to the decontamination of small items, an original method involving a topping gel has been developed. A polysaccharide, carrageenan, is added to a conventional gel (silica particles + reactive solution) and by varying the temperature an abrupt sol-gel transition (around 45-50 degrees C) is observed. At high temperature, the low viscosity of the gel allows it to coat small parts easily, and simply removing them from the warm bath congeals the topping gel. Its decontaminating action takes place. The gel then dries and can be collected. A tradeoff has been found between the mineral mass fraction and the amount of carrageenan, and a formulation is proposed. Results on Co-60 contaminated black steel plates show that the decontamination factor is fully comparable to a conventional gel. Finally, drying kinetic measurements show that easily recoverable flakes are formed due to water evaporation

Study of metal nanoparticles stabilised by mixed ligand shell: a striking blue shift of the surface-plasmon band evidencing the formation of Janus nanoparticles.

International audienc