Noir de carbone

Résumé

Le noir de carbone, aussi appelé noir de fourneau, noir thermique, noir au tunnel, noir d'acétylène, ou autrefois noir de fumée ou noir de lampe, est une forme amorphe et élémentaire du carbone ; on le trouve dans les suies et sous forme de carbone colloïdal. C'est la forme de carbone élémentaire la plus répandue et utilisée. Il n'a pas d'odeur. Le noir de carbone est massivement produit par l'industrie de la pétrochimie, par combustion incomplète d'hydrocarbures (ex. : produits pétroliers lourds comme le goudron de houille) ou d'huile végétale ; la capacité mondiale était de plus de 10 millions de tonnes en 2005. Les différents noirs de carbone se présentent sous forme de poudres constituées de particules sphériques de à , qui forment des agrégats de à ; ces agrégats peuvent former des agglomérats de à ou être transformés en granules de à . Le noir de carbone est l'un des polluants de l'air quand il est émis par les pots d'échappement (des moteurs Diesel principalement) et p

Source officielle

https://fr.wikipedia.org/wiki/Noir_de_carbone

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We report the extraction of silicon via a carbothermal reduction process using a CO2 laser beam as a heat source. The surface of a mixture of silica and carbon black powder became brown after laser beam irradiation for a few tens of seconds, and clear peaks of crystalline silicon were observed by Raman shift measurements, confirming the successful carbothermal reduction of silica. The influence of process parameters, including the laser beam intensity, radiation time, nitrogen gas flow in a reaction chamber, and the molar ratios of silica/carbon black of the mixture, on the carbothermal reduction process is explained in detail.

NATURE RESEARCH2020

Chargement

Electrochemical Reduction of Protic Supercritical CO2 on Copper Electrodes

Alberto Battistel, Victor Costa Bassetto, Olga Melchaeva, Patrick Voyame

The electrochemical reduction of carbon dioxide is usually studied in aqueous solutions under ambient conditions. However, the main disadvantages of this method are high hydrogen evolution and low faradaic efficiencies of carbon-based products. Supercritical CO2 (scCO(2)) can be used as a solvent itself to suppresses hydrogen evolution and tune the carbon-based product yield; however, it has received little attention for this purpose. Therefore, the focus of this study was on the electrochemical reduction of scCO(2). The conductivity of scCO(2) was increased through the addition of supporting electrolyte and a cosolvent (acetonitrile). Furthermore, the addition of protic solutions of different pH to scCO(2) was investigated. 1m H2SO4, trifluoroethanol, H2O, KOH, and CsHCO3 solutions were used to determine the effect on current density, faradaic efficiency, and selectivity of the scCO(2) reduction. The reduction of scCO(2) to methanol and ethanol are reported for the first time. However, methane and ethylene were not observed. Additionally, corrosion of the Cu electrode was noticed.

Wiley-VCH Verlag Berlin2017

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Solid electrochemical energy storage for aqueous redox flow batteries: The case of copper hexacyanoferrate

Christopher Raymond Dennison, Solène Cindy Gentil, Hubert Girault, Grégoire Clément Gschwend, Pekka Eero Peljo, Danick Reynard, Evgeny Smirnov, Elena Zanzola

All redox flow batteries suffer from low energy storage density in comparison with conventional Li-ion batteries. However, this issue can be mitigated by utilization of solid energy storage materials to enhance the energy storage capacity. In this paper we demonstrate the utilization of copper hexacyanoferrate (CuHCF) Prussian blue analogue for this purpose, coupled with N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride (TEMPTMA) as a soluble redox mediator to target the redox transitions of the solid material. In this case, indirect charging and discharging of CuHCF suspended in the electrolyte by electrochemically oxidized/reduced TEMPTMA was observed by chronoamperometry. Secondly, electrochemistry of different CuHCF composites with carbon black and multi-walled carbon nanotubes were investigated, highlighting that the high conductivity of the solid energy storage materials is crucial to access the maximal charge storage capacity. Finally, a CuHCF-TEMPTMA/Zn aqueous redox flow battery achieved stable cycling performances with high coulombic efficiency of 95% and volumetric capacity of 350 C mL−1.

2019

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