NMR study of intrinsic diffusion and reaction in CsNaX type zeolites

Flux response technology applied in zero length column diffusivity measurements

“…The experiments were carried out isothermally for three complete dynamic cycles across a temperature range of 25 • C to 100 • C. A mathematical model was developed in Maple to calculate the diffusion coefficients generated from the theoretical ZLC models derived through experimentation. The diffusion coefficients obtained are consistent with previously reported macroscopic data (Granato et al 2010) and compare well when evaluating the structural differences (Sun et al 1996a(Sun et al , 1996b Propane ZSM-5 5.0 QENS 300 2.0 × 10 −11 (Jobic et al 1992) Propane NaX zeolite 7.9 PFG-NMR 307 7.0 × 10 −10 (Schwarz et al 1995) Propane 13X zeolite 7.9 MD simulations 373 2.9 × 10 −9 (Granato et al 2010) of the washcoats of each sample. FRT was also able to successfully compare and contrast the diffusivity differences between ad and desorption transients within the washcoat of monolith samples to shed further light on microporous diffusivity studies.…”

Diffusion Measurements by NMR Techniques

“…Presently, it is difficult to decide whether in addition to the ample information provided by in-situ MAS NMR on chemical reactions [166][167][168][169], PFG NMR is able to provide substantial news about molecular transportation which is not available by equilibrium measurements. Figure 20 shows the diffusivities of isopropanol, acetone and propene under the conditions of single-component adsorption on zeolite Na-X [170]. All three compounds are involved in a well-established test reaction to discriminate between acid and basic zeolites [171,172]: Isopropanol is dehydrated to propene on acid catalysts, while it is dehydrogenated to acetone on basic catalysts.…”

Diffusion in Nanoporous Solids in the Focus of IUPAC – A Tribute to Jens Weitkamp

“…It is this type of application, which found Jens Weitkamp's particular interest. He was among the first to combine the information provided by NMR spectroscopy on diffusion and reaction in zeolites [121][122][123] and thus set the course for Stuttgart to become a world-wide recognized center for the application of NMR spectroscopy not only of nanoporous materials, but also for the in situ analysis of chemical reactions in porous catalysts [124][125][126].…”