129Xe-NMR study of coke distribution in dealuminated HY zeolites

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

“…For coke deposits up to 10 wt%, the supercages are filled with coke and the remaining internal void space consists of narrow channels. Beyond 10 wt%, the coke deposits on the external surface of the zeolite particles as well, which gives rise to micro cavities between the crystallites [415]. Coking and regeneration of catalysts applied in fluid catalytic cracking have been studied by 129Xe NMR spectroscopy at different stages of regeneration [414].…”

“…According to the authors this behavior can be explained by a structural change which destabilizes the adsorption sites in double eightrings relative to positions in the a-cages. Bonardet et al [4l3,414] and Barrage et al [415] applied 129Xe NMR spectroscopy to monitor the formation of coke inside the zeolite particles. The authors demonstrated that non-framework aluminum species are involved in the coke formation.…”

129Xenon NMR: Review of recent insights into porous materials

“…129 Xe NMR spectra of xenon diffusing in the interpillar structure of TEAhectorite at variable temperature. From reference [116] with permission. 129 Xe CP MAS (upper) and DQ filtered (lower) spectra for Dianin's compound prepared under (a) 1 atm of Xe gas enriched to 99% in 129 Xe and (b) 3 atm of Xe gas with natural abundance (26%) 129 Xe.…”

“…It is therefore of interest to check if the species have suitably been deposited within the pores. As it was reported in the past, 129 Xe NMR appears to be an appropriate technique to investigate the location of the species in the zeolite [7,[105][106][107][108][109][110][111][112][113][114][115][116].…”

129Xe NMR overview of xenon physisorbed in porous solids

“…A complete study of coke distribution in deactivated HY zeolite was performed by Barrage et al 70 The variations of the chemical shift υ with xenon concentration and adsorption temperature allowed the authors to show that the coke is deposited first on extraframework aluminium, masking Xe-Al interactions (υ-plots are linear over the entire range of xenon concentration). At low coke content, carbonaceous residues are heterogeneously deposited and mainly located at the windows of the supercages.…”