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11. Evaluation of Zeolite Composites by IR and NMR Spectroscopy.

Author

Dalena, Francesco, Dib, Eddy, Onida, Barbara, Ferrarelli, Giorgia, Daturi, Marco, Giordano, Girolamo, Migliori, Massimo, and Mintova, Svetlana

Subjects
INFRARED spectroscopy, BRONSTED acids, NUCLEAR magnetic resonance, CRYSTAL growth, ZEOLITES
Abstract

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 grew differently when the ZSM-5 core was in the H+ form (empty pores) compared to when the OSDA was still present in the sample. This distinction was evident in the textural properties, with a decrease in the 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 29Si 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 Q4 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 1H NMR. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Mesoporous benzene-silica hybrid materials with a different degree of order in the wall structure: An IR comparative study

Author

Onida, Barbara, Garrone, Edoardo, Camarota, Beatrice, Ugliengo, Piero, Goto, Yasutomo, and Inagaki, Shinji

Subjects
Benzene -- Chemical properties, Silicon compounds -- Chemical properties, Porous materials -- Chemical properties, Chemicals, plastics and rubber industries
Abstract

A joint IR and computational work has allowed a detailed characterization of the isolated silanols at the surface of highly ordered benzene-silica hybrid material and a similar characterization was presented for a less ordered sample. The result reveals that the molecules with simultaneous H-acceptor and H-donor properties might interact with both the acidic proton and in silanols and the electronic cloud in the framework aromatic rings.

Published
2005

44. In situ infrared study of SBA-15 functionalized with carboxylic groups incorporated by a co-condensation route

Author

Fiorilli, Sonia, Onida, Barbara, Bonelli, Barbara, and Garrone, Edoardo

Subjects
Carboxylic acids -- Chemical properties, Condensation products (Chemistry) -- Chemical properties, Infrared spectroscopy -- Usage, Chemicals, plastics and rubber industries
Abstract

The reaction of carboxylic groups in an ordered SBA-15, incorporated via co-condensation is studied by infrared spectroscopy. It is observed that they react reversibly with ammonia at room temperature, with the formation of carboxylate species and ammonium ions and so it is concluded that it is isolated and non interacting with each other.

Published
2005

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