Application of ¹¹⁹Sn CPMG MAS NMR for Fast Characterization of Sn Sites in Zeolites with Natural ¹¹⁹Sn Isotope Abundance

Abstract

(119)Sn CPMG MAS NMR is demonstrated to be a fast and efficient method for characterization of Sn-sites in Sn-containing zeolites. Tuning of the CPMG echo-train sequence decreases the experimental time by a factor of 5-40 in the case of as-synthesized and hydrated Sn-BEA samples and by 3 orders of magnitude in the case of dehydrated Sn-BEA samples as compared to conventional methods. In the latter case, the reconstruction of the quantitative spectrum without the loss of sensitivity is shown to be possible. The method proposed allows obtaining (119)Sn MAS NMR spectra with improved resolution for Sn-BEA zeolites with natural (119)Sn isotope abundance using conventional MAS NMR equipment.

Active Site Hydration Governs the Stability of Sn-Beta during Continuous Glucose Conversion

“…[37][38] In line with recent developments, spectra were recorded by Carr-Purcell-Meiboom-Gill (CPMG) echo-train acquisition methods, as exemplified by the Ivanova group. 39,40 Due to the signal enhancements made possibly by CPMG methods, spectra could be recorded on materials containing naturally abundant quantities of Sn. All ex reactor samples were measured without prior heat treatment, in order to preserve integrity of the samples following operation, and were thus compared to fresh samples also in their hydrated forms.…”

Interrogating the Lewis Acidity of Metal Sites in Beta Zeolites with 15N Pyridine Adsorption Coupled with MAS NMR Spectroscopy

“…31,35 Recently, Ivanova et al showed that other methods could be used to obtain enhanced signals with unlabeled samples. 36 Other metals of interest, including Ti, Zr, and Hf, suffer from extreme challenges in NMR sensitivity that stem from low natural abundance, large quadrupolar moment, and/or low gyromagnetic ratios (as shown in Table S1). 37 …”

Synthesis of a novel polyester building block from pentoses by tin-containing silicates

“…Recent work aimed at elucidating the catalytic functioning of Sn-Beta includes DFT calculations, FT-IR, TPR and 119 Sn-NMR spectroscopy. [39][40][41][42][43][44] Despite it being a crystalline material, the preparation method oen greatly inuences the catalytic performance. Two principally different preparation methods are normally used, direct synthesis under hydrothermal conditions using hydrouoric acid as mineralising agent [Sn-Beta (HT)] and synthesis by post treatment of a dealuminated Beta zeolite with a tin source [Sn-Beta (PT)].…”