Adsorption of Remazol Black B dye on Activated Carbon Felt

The adsorption of Remazol Black B (anionic dye) on a microporous activated carbon felt is investigated from its aqueous solution. The surface chemistry of activated carbon is studied using X-ray microanalysis, "Boehm" titrations and pH of PZC measurements which indicates that the surface oxygenated groups are mainly acidic in nature. The kinetics of Remazol Black B adsorption is observed to be pH dependent and governed by the diffusion of the dye molecules. The experimental data can be explained by "intra-particle diffusion model". For Remazol Black B, the Khan model is best suited to simulate the adsorption isotherms

Multi-technique characterization of biochar formation

It is known that biomass forms an intermediate liquid before forming the solid “char” (figure 1) but the role of this intermediate liquid on the structure of char and on the mechanisms of pyrolysis is still poorly understood. In this talk we will present how in-situ rheology and 1H NMR analysis [2] are interesting technique to understand the mechanism of biochar formation through an intermediate “visco-elastic” material. These techniques allow assessing the physical-chemistry of biomass conversion to char at real-time and high temperature conditions. Please click on the file below for full content of the abstract

Physico-chemical qualities and potentials for biochar agro- environmental valorization

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Characterization and catalytic performances of biochars synthesized from a hyperaccumulator plant: Alyssum murale

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Characterization of biochars by nuclear magnetic resonance

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Hydrogen production by methane decomposition over Ni-doped activated carbons: effect of the activation method

Ni supported over activated carbon (AC) based on olive stones were tested for methane decomposition to produce hydrogen. Physical (by $\mathrm{H}_{2}\mathrm{O}$) and chemical (by $\mathrm{H}_{3}\mathrm{PO}_{4}$) activations were compared. Kinetic parameters of methane decomposition were determined depending on Ni load, methane partial pressure and reaction temperature. The catalysts were characterized before and after reaction by $\mathrm{N}_{2}$ adsorption, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The catalysts showed good initial activities that increased with temperature and nickel load, reactivity decreased with time. The reaction orders were 0.63 and 0.74 and the activation energies were 122 and 139 kJ/mol for physically and chemically activated carbon, respectively. BET surface areas and pore volumes decreased dramatically after reaction due to the deposit of carbon on the support. Ni stayed under its metallic form on the physically AC whereas it was mainly present as $\mathrm{Ni}_{12}\mathrm{P}_{5}$ over the chemically activated one. TEM characterization revealed the formation of well-organized carbon nano-onions surrounding Ni particles on the physically activated carbon. Nano-onions were not formed around $\mathrm{Ni}_{12}\mathrm{P}_{5}$ particles in the chemically activated carbon. The physical activation allowed the synthesis of catalysts with a better stability for methane conversion than what chemical activation would allow

Hydrogen production by methane decomposition over Ni-doped activated carbons: effect of the activation method

Ni supported over activated carbon (AC) based on olive stones were tested for methane decomposition to produce hydrogen. Physical (by $\mathrm{H}_{2}\mathrm{O}$) and chemical (by $\mathrm{H}_{3}\mathrm{PO}_{4}$) activations were compared. Kinetic parameters of methane decomposition were determined depending on Ni load, methane partial pressure and reaction temperature. The catalysts were characterized before and after reaction by $\mathrm{N}_{2}$ adsorption, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The catalysts showed good initial activities that increased with temperature and nickel load, reactivity decreased with time. The reaction orders were 0.63 and 0.74 and the activation energies were 122 and 139 kJ/mol for physically and chemically activated carbon, respectively. BET surface areas and pore volumes decreased dramatically after reaction due to the deposit of carbon on the support. Ni stayed under its metallic form on the physically AC whereas it was mainly present as $\mathrm{Ni}_{12}\mathrm{P}_{5}$ over the chemically activated one. TEM characterization revealed the formation of well-organized carbon nano-onions surrounding Ni particles on the physically activated carbon. Nano-onions were not formed around $\mathrm{Ni}_{12}\mathrm{P}_{5}$ particles in the chemically activated carbon. The physical activation allowed the synthesis of catalysts with a better stability for methane conversion than what chemical activation would allow

Etude experimentale et modelisation de la combustion d'un grain de charbon

SIGLEINIST TD 19973 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Étude des mécanismes d adsorption sur des matériaux carbonés

Les problèmes liés aux gaz à effets de serre ne pouvant plus être négligés et le coût du pétrole augmentant sans cesse, l hydrogène est une solution de remplacement de plus en plus envisagée. C est pourquoi nous avons étudié l adsorption d hydrogène qui pourrait permettre de le stocker de façon plus efficace que les autres méthodes utilisé à l heure actuelle. Cette étude se divise en 3 parties : La synthèse de matériaux microporeux La caractérisation texturale de ces matériaux. L adsorption d hydrogène à différentes températures et à différentes pressions. Pour synthétiser des matériaux carbonés modèles, nous avons utilisé les procédés de réplique négative et d activation chimique. Tous les matériaux synthétisés et quelques carbones activés commerciaux sont caractérisés par adsorption de gaz, par diffraction ou transmission de rayons X et par microscopie électronique à transmission. L adsorption d hydrogène dans ces carbones est mesurée à 77K et à température ambiante de quelques Pascals jusqu à 50 bars. Ces mesures nous donnent les capacités de stockages de chaque carbone et ce à différentes pressions, et ainsi avoir une meilleure compréhension des phénomènes d adsorption.The problems related to greenhouse gases could no longer be neglected and the cost of oil increasing steadily, hydrogen is an alternative to increasingly considered. That is why we have studied the adsorption of hydrogen which could store more efficiently than other methods used at present. This study is divided into 3 parts: The synthesis of microporous materials. The textural characterization of these materials. The adsorption of hydrogen at different temperatures and different pressures. To synthesize carbon materials models, we used the replica negative processes and chemical activation. All materials synthesized and some commercial activated carbons are characterized by gas adsorption, X-ray transmission or diffraction, and transmission electron microscopy. The adsorption of hydrogen in carbon is measured at 77K and at room temperature a few Pascals up to 50 bars. These measures give us the storage capacity of each carbon and at different pressures, and thus have a better understanding of adsorption phenomena.MULHOUSE-SCD Sciences (682242102) / SudocSudocFranceF

Etude cinétique de la formation et réduction du monoxyde d'azote lors de la combustion du charbon à haute température

Afin de permettre l’optimisation des brûleurs et chambres de combustion, il est nécessaire de déterminer les mécanismes réactionnels de la formation et réduction de NO dans les conditions du charbon pulvérisé (1000-1300 C). Pour ce faire, des expériences ont été effectuées dans un four à chute à différentes températures, concentrations de NO, CO, O2 et résidu carboné et temps de séjour. Les ordres apparents de réaction sont égaux à 0,9 par rapport à NO dans le cas de la réduction de NO et à 0,8 par rapport à O2 dans le cas de la formation de NO. Par ailleurs, une influence de CO sur la réduction de NO a été observée, ce qui confirme une libération de sites pour la réaction C/NO plutôt qu’une réaction catalytique CO/NO. La simulation de la combustion des particules à l'aide d'un modèle bidimensionnel établi à partir de FLUENT a permis la détermination des paramètres cinétiques pour la réduction de NO (59*exp[14400/T] m/s) et pour la formation de NO 100*exp[9600/T] m/s).The aim of this study is to determine the kinetics of the heterogeneous NO formation and reduction at pulverized coal combustion conditions (1000-1300 C) to allow the simulation and optimisation of the burner and combustion-chamber geometry for low NOx emissions. Experiments were performed in a drop tube furnace for various temperatures, NO, CO, O2 and char concentration and reaction times. The apparent reaction orders for NO reduction are 0.9 towards NO and 1 towards char. CO concentration showed a small effect on NO reduction. Hence this effect is not linear to CO concentration. In consequence it seems that CO interacts by freeing active sites for NO-C reaction rather than by surface catalysed reaction with NO. Kinetic parameters of NO-reduction (59*exp[14400/T] m/s) and NO-formation (100*exp[9600/T] m/s) were determined by simulation, using a complete 2-D simulation developed with FLUENT. Particle combustion using a reduced kinetic model was implemented with user defined functions.MULHOUSE-SCD Sciences (682242102) / SudocSudocFranceF