Issue 1, 1989

The properties of boralites studied by infrared spectroscopy

Abstract

Because of its small dimensions boron is three-coordinated in boralites and is situated in one face of a tetrahedral hole. The i.r. band of the B—O asymmetric stretch in BO3 units is split into two maxima (at 1380 and 1405 cm–1), thus suggesting that two kinds of boron sites exist in boralites. Boron becomes four-coordinated following adsorption of the electron-donor molecules NH3, H2O and pyridine, but not of benzene. Three kinds of OH groups (at 3680, 3720 and 3460 cm–1) are formed following the subsitution of Na+ ions by protons. The 3720 cm–1 OH groups act as Brønsted-acid sites in the reaction with pyridine. The concentration of Brønsted sites determined by pyridine sorption is comparable with theoretical values. The low strength of the Brønsted-acid sites (illustrated by pyridine thermodesorption experiments) can be explained by the large separation and weak interaction between boron and the OH groups in the O3B⋯OH–SiO3 units. The electrostatic field of the Lewis-acid sites in boralites is stronger than that in zeolites.

Article information

Article type
Paper

J. Chem. Soc., Faraday Trans. 1, 1989,85, 47-53

The properties of boralites studied by infrared spectroscopy

J. Datka and Z. Piwowarska, J. Chem. Soc., Faraday Trans. 1, 1989, 85, 47 DOI: 10.1039/F19898500047

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements