0000000000277117
AUTHOR
Maxence Giraudet
New force field for GCMC simulations of D 2 /H 2 quantum sieving in pure silica zeolites
International audience; We report a study on adsorption and coadsorption of H2 and D2 in FAU, MFI and CHA pure silica zeolites having different pore sizes and shapes. Adsorption capacities, selectivities, enthalpies and entropies are determined by combining experiments and GCMC simulations. We show that the force fields available in the literature cannot predict the adsorption equilibria below 77 K with sufficient accuracy. Here we propose a new force field adjusted by using our experimental data obtained for the pure silica MFI zeolite at 65 K and 77 K. With this new force field, it is possible to predict the adsorption and coadsorption equilibria on the three zeolite structures in a tempe…
Coadsorption of hydrogen and deuterium on zeolites at cryogenic temperatures : influence of the sorbent’s properties on selectivity
The adsorption of hydrogen and deuterium (single gases and mixtures) was studied on a series of zeolites with varied parameters (Si/Al ratio, nature of the charge-compensating cation, pore geometry and diameter of pore aperture). Thermodynamic adsorption selectivities towards deuterium with respect to hydrogen were measured in a large pressure range (0.1 – 1000 hPa) and for several temperatures (45 – 100 K). The adsorption selectivity was assessed using direct coadsorption measurements performed by manometry coupled with mass spectrometry. For all studied zeolites and experimental conditions, the coadsorption process is selective towards deuterium, in agreement with the literature. However,…
Enhancement of D 2 /H 2 Selectivity in Zeolite A through Partial Na–K Exchange: Single-Gas and Coadsorption Studies at 45–77 K
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
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 > …