In situ FTIR microscopic investigation of the acid sites in cloverite

G. Müller, G. Eder-Mirth, J.A. Lercher

Research output: Contribution to journalConference articleAcademicpeer-review

7 Citations (Scopus)
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Abstract

Cloverite, a microporous gallophosphate has attracted great attention as it possesses unusually large micropores. Cloverite possesses two types of structural hydroxyl groups (Ga-OH and P-OH groups), which exhibit high and moderate Br6nsted acid strength toward apolar hydrocarbon molecules. Sorption of polar base molecules on the Ga-OH groups, however, leads to a breaking of the Ga-O bond close to the Ga-OH adsorption site, resulting in a concerted Lewis and Br6nsted type interaction. For small molecules (like ammonia), multiple sorption at these sites causes a local rearrangement of the lattice leading to a collapse of the microporous structure upon thermal desorption of the probe molecules. Small alcohols are chemisorbed quite differently on the Ga-OH groups of cloverite compared to other acidic molecular sieves leading to the formation of dimethylether and formaldehyde upon desorption. The structural hydroxyl groups of cloverite exhibit high and moderate Bronsted acid strength toward apolar hydrocarbon molecules. With polar molecules, these hydroxyl groups show unique interactions leading to a local rearrangement of the lattice including a breaking of the Ga-O bond close to the Ga-OH sorption site. Consequently, a concerted Lewis and Br6nsted acid type interaction is concluded to exist between the basic molecules and the Ga-OH/Ga cation sorptionsites.

Original languageEnglish
Pages (from-to)71-77
Number of pages7
JournalStudies in surface science and catalysis
Volume97
Issue numberC
DOIs
Publication statusPublished - 1995
EventInternational Zeolite Symposium 1995 - Québec, Canada
Duration: 15 Oct 199520 Oct 1995

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