0000000000755244
AUTHOR
Céline Dirand
showing 4 related works from this author
The functionalization of nanodiamonds (diamondoids) as a key parameter of their easily controlled self-assembly in micro- and nanocrystals from the v…
2014
We detail herein readily accessible processes to control previously unobserved robust self-assemblies of nanodiamonds (diamondoids) in micro- and nanocrystals from their mild vapor deposition. The chemical functionalization of uniform and discernible nanodiamonds was found to be a key parameter, and depending on the type of functional group (hydroxy, fluorine, etc.) and its position on the diamondoid, the structure of the discrete deposits can vary dramatically. Thus, well-defined anisotropic structures such as rod, needle, triangle or truncated octahedron shapes can be obtained, and self-assembled edifices of sizes ranging from 20 nm to several hundred micrometers formed with conservation …
D2 and H2 adsorption capacity and selectivity in CHA zeolites: Effect of Si/Al ratio, cationic composition and temperature
2020
International audience; The work deals with the effect of composition of CHA zeolites on the adsorption and separation of H2 and D2 under cryogenic temperatures. In the first part of this work the effect of Si/Al ratio and cationic composition on single gas adsorption of H2 and D2 was studied at 77.4 K. It was found that the adsorption capacities increase with Al content up to Si/Al = 2.1. Unexpectedly, Na-CHA zeolite with the highest Al content (Si/Al = 1.1) adsorbs only negligible amount because of the collapse of the zeolite structure upon dehydration at 400°C. The Na-and Li-containing chabazites with Si/Al = 2.1 possess similar adsorption capacities. In contrast, progressive replacement…
Enhancement of D 2 /H 2 Selectivity in Zeolite A through Partial Na–K Exchange: Single-Gas and Coadsorption Studies at 45–77 K
2020
International audience; We report D2/H2 adsorption selectivities under cryogenic temperatures (45-77 K) in Na and K-Na exchanged zeolites A (LTA structural code) measured by co-adsorption technique. These values are systematically compared with Ideal Adsorbed Solution Theory (IAST) predictions based on the single gas adsorption isotherms. For NaA zeolite the evolution of the selectivity as a function of total pressure and gas mixture composition at 77 K shows ideal behavior. In contrast, as temperature decreases, D2/H2 selectivity rises exponentially and its values can no longer be predicted by IAST. We found that in these conditions the evolution of the selectivity can be described by a si…
D2/H2 adsorption selectivity on FAU zeolites at 77.4 K: Influence of Si/Al ratio and cationic composition
2018
Abstract Equilibrium D2/H2 adsorption selectivity was determined at 77.4 K below 1000 hPa for a series of FAU type zeolites X exchanged with different cations (Li+, Na+, K+, Mg2+, Ca2+, Ba2+ and Mn2+). In addition NaY, DAY (dealuminated Y) and pure silica CHA and MFI zeolites were studied. Two experimental approaches were used to determine the D2/H2 adsorption selectivity: direct determination at the thermodynamic equilibrium from manometric coadsorption experiments and calculations by Ideal Adsorbed Solution Theory (IAST) from single gas adsorption isotherms. While these two approaches are not in quantitative agreement, they reveal similar trends. At low loading ( MnX > LiX > CaX ≈ NaX > …