Revealing the Specific Spatial Confinement in 8‐membered Ring Cage‐type Molecular Sieves via Solid‐state NMR and Theoretical Calculations

Abstract

Spatial confinement plays a significant role in selective adsorption and catalysis of molecular sieves. In this work, the adsorption behaviors of methanol in 8‐membered ring cage‐type molecular sieves DNL‐6 and SAPO‐42 were investigated by 13C solid‐state NMR (ssNMR) and density functional theory (DFT) calculations. Confinement‐induced spatial orientation of guest molecules in molecular sieves was revealed with considering both confined space and active centers. Confined space of double 8‐membered rings (D8R) in DNL‐6 favors the adsorption of methanol, accompanied by the methyl groups orientating to D8R space and the hydroxyl groups of methanol anchored by Brønsted acid site (BAS).

Correlating the Adsorption Preference and Mass Transfer of Xenon in RHO-Type Molecular Sieves

“…Such a confinement effect of D8R on the adsorption of other molecules has also been confirmed in recent work. 45,53 It should be especially noted that the observed red dots in the center of the lta cavity are attributed to the overlapped projection from xenon adsorbed in the D8R prism, and few xenon atoms are gathered at this location (Figure S3).…”

Modelling complex molecular interactions in catalytic materials for energy storage and conversion in nuclear magnetic resonance

“…As presented in Figure 5A, the chemical shifts of methanol with lta orientation in DNL-6 (51.4 and 51.2 ppm for site O1 and O2) are similar to that adsorbed in the lta cavity of , whereas the chemical shifts of D8R orientation (52.1 and 52.4 ppm for O1 and O2) are roughly 1.0 ppm higher than that of lta orientation, which coincides with the 13 C NMR experiment. It is concluded that the confined space of double 8membered rings in DNL-6 promotes the methanol adsorption accompanied by the methyl groups orienting to D8R space and the hydroxyl groups of methanol anchored by Brønsted acid sites (Lou et al, 2021). Methane selective conversion is essential in C1 chemistry.…”

“…The selection of the exchange-correlation functional (method accuracy) introduces ±1.5 ppm uncertainty in the computed chemical shifts (Kolganov et al, 2020a). Philippou et al utilized 13 C NMR conjunction with DFT to identify different methoxy (Lou et al, 2021). © 2020 Wiley-VCH Verlag GmbH (B) 2D 1H-13C HETCOR ssNMR of MgCl2/TiCl4/THF Ziegler-Natta Precatalsyt coupled with DFT calculated adsorption modes for THF.…”

“…FIGURE 5 (A) Optimized geometries of the methanol adsorbed DNL-6 (a-d) and SAPO-42 zeolites: (a) adsorbed on O1 site with D8R orientation, (b) adsorbed on O2 site with D8R orientation, (c) adsorbed on O1 site with lta cage orientation, (d) adsorbed on O2 site with lta cage orientation, (e) adsorbed on the O1 site of SAPO-42. Reprinted with permission from ref(Lou et al, 2021). © 2020 Wiley-VCH Verlag GmbH (B) 2D 1H-13C HETCOR ssNMR of MgCl2/TiCl4/THF Ziegler-Natta Precatalsyt coupled with DFT calculated adsorption modes for THF.…”