Extraction par un fluide supercritique

L'extraction par un fluide supercritique (EFS) est un procédé d'extraction d'un soluté d'une substance en utilisant un fluide supercritique comme solvant d'extraction. Ce procédé ressemble au procédé d'extraction par un liquide. Fluide supercritique Le dioxyde de carbone (CO2) supercritique est le fluide le plus utilisé. Ses avantages sont surtout sa non toxicité et son inertie chimique. Lors de l'extraction, les conditions d'utilisation du dioxyde de carbone supercritique sont au-dessus de ses points critiques (température critique 31 °C et pression critique 74 bar). Le dioxyde de carbone est apolaire et donc a quelquefois de faibles pouvoirs de dissolution et ne peut donc pas être utilisé comme solvant surtout pour les solutés polaires. Pour surmonter cette limitation, il est quelquefois accompagné de co-solvants comme l'éthanol ou le méthanol. Procédé thumb|right|Schématisation d'un appareil de séparation par fluide supercritique L'extraction se fait en deux

Macroporous Materials as Novel Catalysts for Efficient and Controllable Proteolysis

Liang Qiao, Jiawei Tang, Jingjing Wan

A novel nanopore based digestion strategy has been developed by directly adding a macroporous material as catalyst to the conventional in-solution reaction system. Without increasing the enzyme or protein concentrations, this simple digestion approach exhibits high proteolysis efficiency and selectivity due to the in situ fast adsorption of both enzymes and proteins from bulk solution into the macropores of the catalysts, where the target substrates and enzymes are greatly concentrated and confined in the nanospace to realize a quick digestion. Based on the electrostatic interaction matching between the biomolecules and catalysts, selective extraction and digestion of proteins with different isoelectric points can be achieved by adjusting the surface charge of the catalysts. This nanoporous reaction system has been successfully applied to the analysis of a complex biological sample, where 293 proteins are identified, while only 100 proteins are obtained by the standard overnight in-solution digestion. The present nanospace confined digestion strategy will lead to promising advances not only in proteomics but also in other applications where enzymatic reactions are involved.

American Chemical Society2009

Photocatalytic and Electrocatalytic Reduction of Carbon Dioxide in Pressurized Systems

Patrick Voyame

The depletion of carbon-based fossil fuels and the rise in atmospheric carbon dioxide concentration will force an inevitable change in the future global energy landscape. CO2 reduction presents the advantages of decreasing its atmospheric concentration and storing energy in chemical form in CO2 reduction products. With a predicted conversion to renewable energy such as solar or wind energy, energy storage will become a key process in the near future for buffering the fluctuating energy production. The objective of the present work was to study the efficiency towards CO2 reduction of different molecular catalysts. In particular, conducting experiments in high-pressure and supercritical conditions and observing the effect of CO2 pressure or concentration on the efficiency and selectivity of the reaction. As supercritical CO2 (scCO2) has poor solubilisation capabilities, experiments were conducted in biphasic systems or with addition of an organic co-solvent. To drive the reduction reaction of CO2, a catalyst is needed to overcome the kinetic limitations of the reaction, but an energy input is also necessary. Three different forms for this energy input were used in this work. In a first time a sacrificial product, decamethylferrocene (DMFc), was used to transfer electrons to CO2 in biphasic water/scCO2 systems. Complete oxidation of the DMFc was observed in presence of anion capable of transporting protons from water to the DMFc present in the supercritical phase. A photosensitization cycle was used to supply a water soluble catalyst, NI(II)Cyclam, in electron at the required potential to drive the reduction of CO2 into carbon monoxide in water/scCO2 system. The creation of the interface in the system appeared highly favourable to the efficiency of the catalyst. A second catalyst, a ruthenium polypyridyl carbonyl complex, was used for the photocatalytic reduction of CO2. Pressure had an important impact on the production of one of the two reduction product, carbon monoxide, while the production of formate was unaffected by CO2 pressure. As limitations in productivity in photocatalytic experiments were coming principally from the photosensitizer cycle or the sacrificial electron donor, photosensitizer was replaced by an electrode to provide the catalyst in electrons. Voltammetry in CO2-expanded liquids was described and determination of important parameters such as catalyst concentration and diffusion coefficient as a function of pressure was performed. Electrocatalytic reduction of CO2 by ruthenium and rhenium polypyridyl carbonyl complexes was studied in CO2-expanded liquids. The catalytic mechanisms were observed to be highly influenced by CO2 concentration.

EPFL2016

Photocatalytic and Electrocatalytic Reduction of Carbon Dioxide in Pressurized Systems

Patrick Voyame

EPFL2016

Extraction par un fluide supercritique

Macroporous Materials as Novel Catalysts for Efficient and Controllable Proteolysis

Discussion on Hydraulic behaviour of junction manholes under supercritical flow conditions by J. Saldarriaga, N. Bermúdez and D. P. Rubio

Photocatalytic and Electrocatalytic Reduction of Carbon Dioxide in Pressurized Systems

Photocatalytic and Electrocatalytic Reduction of Carbon Dioxide in Pressurized Systems

Macroporous Materials as Novel Catalysts for Efficient and Controllable Proteolysis

Discussion on Hydraulic behaviour of junction manholes under supercritical flow conditions by J. Saldarriaga, N. Bermúdez and D. P. Rubio