129Xe n.m.r. study of adsorbed xenon: A new method for studying zeolites and metal-zeolites

Structure and acidity of Mo/H-MCM-22 catalysts studied by NMR spectroscopy

“…4. In general, the observed chemical shift in the low xenon loading (Henry's law) regime can be expressed by the following equation [7][8][9][23][24][25][26][27]: Xe loading) to the chemical shift axis. On the other hand, the last term proportional to r is the characteristic of XeXe interactions.…”

“…On the other hand, it has been shown that the slope (s Xe ) of the d(r) versus r plot (Fig. 3) in the low Xe loading regime should be inversely proportional to the effective free volume of the intracrystalline voids in zeolite [23,27]. That is:…”

“…The structure of MCM-22 zeolite consists of two independent two-dimensional pore systems; namely, the sinusoidal channels with 10-MR openings and the larger 12-MR supercages (0.71 nm  0.71 nm  1.81 nm) interconnected www.elsevier.com/locate/cattod Catalysis Today 97 (2004) [25][26][27][28][29][30][31][32][33][34] by the 10-MR windows [6]. Owing to its extraordinarily large extracrystalline surface area compared to its zeolite counterparts, MCM-22 is more favorable in catalyzing reactions that predominantly occur on the external surface of the catalyst.…”

Characterization of the microvoids of a tetramethyl polycarbonate/polystyrene blend system using Xe sorption measurements and 129Xe NMR spectroscopy

“…Furthermore, Fraissard and collegues 21,22 reported that the chemical shifts of 129 Xe in zeolites without strong charges also shift linearly with increasing amounts of Xe sorbed in them. The pressure dependence of the 129 Xe NMR chemical shift can be interpreted by the interactions between Xe atoms.…”

“…These downfield shifts are caused by increasing interactions among the Xe atoms. 21,22 Additionally, these symmetric peaks indicate that Xe atoms, which are dissolved in the samples, diffuse fast and then rapidly exchange between the Henry and Langmuir sorption sites on the NMR time scale.…”