Wilfried J. Mortier

High-flux MFI membranes

The synthesis and evaluation of high performance MFI-type membranes is described. These systems exhibit fluxes that are one to two orders of magnitude higher than previous literature reports, with ...

Cation site energies in dehydrated KFI-type zeolites : d-NaKFI, d-NaHKFI, and d-KKFI

Abstract The Na- and K-ion distribution in dehydrated KFI-type zeolites ( Si Ai = 3.3) was used as a probe for the computation of the site-energy differences at the hexagonal prism, the puckered (Na and K), and flat eight-rings (K only) using an (exact) statistical thermodynamical model and an X-ray powder diffraction study (Rietveld refinement). The site stability sequence was found to be (center of the hexagonal prism) Si Ai > 3).

Quick scheme for evaluation of atomic charges in arbitrary aluminophosphate sieves on the basis of electron densities calculated with DFT methods

It is demonstrated that unique and simple analytical functions are justified for the atomic charge dependences q of the T (T = Al, P) and O atoms of aluminophosphates (AlPOs) using DFT calculations with several basis sets, starting from STO‐3G to 3‐21G and 6‐21G**. Three internal (bonds, angles, …) coordinates for the charge dependences of the T atoms and four coordinates for the O are sufficient to reach a precision of 1.8% for the fitted q(Al), 1.0% for q(P), and 2.5% for q(O) relatively to the values calculated at any basis set level. The proposed strategy consists in an iterative scheme starting from charge dependences based on the neighbors positions only. Electrostatic potential values are computed to illustrate the differences between the calculated and fitted charges in the considered AlPO models.