Characterization of [Ga]MFI via thermal analysis

Document Type

Article

Publication Date

1-1-1995

Abstract

Gallosilicates isostructural with MFI ([Ga]MFI) with different SiO2 Ga2O3 molar ratios were prepared by hydrothermal synthesis and subsequent calcination and conversion to the proton form. Microbalance weight loss determinations both upon H2 reduction of the calcined [Ga]MFIs and upon reduction of the same materials mechanically mixed with β-Ga2O3 can be used as a simple method for the estimation of both extraframework and framework gallium. This thermogravimetric method is based on the reductive solid-state ion exchange between any extraframework Ga2O3, whether present initially or added, and the protons associated with framework Ga. Thermal analysis of 1-propanamine was also found to be a sensitive test of the state of gallium in gallosillicates and also indicates that extraframework Ga in [Ga]MFI transfers into cationic positions upon H2 reduction. Transfer of Ga into cationic positions results in an increase in the amount of 1-propanamine adsorbed near 600 K during thermal analysis, compared with the proton form of the gallosilicate. Gallium cations also promote the formation of a residue at the end of the thermal analysis experiment. There are indications that the extraframework Ga in [Ga]MFI ion exchanges to a limited degree with protons during the calcination procedure. © 1995.

Publication Source (Journal or Book title)

Zeolites

First Page

725

Last Page

731

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