Article Dans Une Revue Molecules Année : 2024

Evaluation of zeolite composites by IR and NMR spectroscopy

Résumé

In this study, we assessed the quantity, strength, and acidity of zeolite composites comprising Silicalite-1 grown on ZSM-5 crystals using a combination of infrared (IR) and solid-state nuclear magnetic resonance (NMR) spectroscopy. The composites were created through the direct growth of Silicalite-1 crystals on ZSM-5 (P_ZSM-5), either with or without the organic structure-directing agent (OSDA) introduced into the ZSM-5 channels (samples: H_ZSM-5_Sil1 and TPA_ZSM-5_Sil1). The results revealed that Silicalite-1 grows differently when the ZSM-5 core is in the H + form (empty pores) compared to when the OSDA is still present in the sample. This distinction is evident in the textural properties, with a decrease in micropore surface area and an increase in the external surface area in the H_ZSM-5_Sil1 compared to the parent sample. The TPA_ZSM-5_Sil1 composite exhibited characteristics similar to the parent zeolite. These findings were further supported by 29 Si NMR, which revealed a comparable local order for the parent (P_ZSM-5) and TPA_ZSM-5_Sil1 samples, along with a broadening of the Q 4 peak for the H_ZSM-5_Sil1 composite. Additionally, the acid sites were preserved in the TPA_ZSM-5_Sil1 composite, while in the H + -form core, the concentration of Brønsted acid sites significantly decreased. This reduction in isolated Brønsted acid sites was further corroborated by 1 H NMR.

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hal-04808051 , version 1 (27-11-2024)

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Francesco Dalena, Eddy Dib, Barbara Onida, Giorgia Ferrarelli, Marco Daturi, et al.. Evaluation of zeolite composites by IR and NMR spectroscopy. Molecules, 2024, 29 (18), pp.4450. ⟨10.3390/molecules29184450⟩. ⟨hal-04808051⟩
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