Simple quantification of zeolite acid site density by reactive gas chromatography

Omar A. Abdelrahman, Katherine P. Vinter, Limin Ren, Dandan Xu, Raymond J. Gorte, Michael Tsapatsis, Paul J. Dauenhauer

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

The Brønsted acid site densities of ZSM-5, BEA and single unit cell self-pillared pentasil (SPP) zeolites of varying Si/Al ratios were measured using a new technique, reactive gas chromatography (RGC), which utilizes alkylamine decomposition to selectively count Brønsted acid sites. Reactive gas chromatography condenses the conventional temperature-programmed desorption mass spectrometer (TPD-MS) setup into a single, fully-automated gas chromatograph (GC). Alkylamine decomposition reactions were conducted in a microcatalytic reactor placed within a temperature-controlled GC inlet liner. Products were then separated in a GC column and quantified with a flame ionization detector. A comparison between reactive gas chromatography measurements and conventional temperature programmed desorption methods showed agreement; RGC acid site density measurements were further confirmed by comparison with in situ pyridine titration of isopropanol dehydration. Reactive gas chromatography measurements performed using multiple alkylamines, were found to yield identical Brønsted acid site densities. The method of reactive gas chromatography was found to be highly sensitive, where siliceous materials with Brønsted acid site densities as low as ∼1.0 μmol gcat-1 could be reliably measured.

Original languageEnglish (US)
Pages (from-to)3831-3841
Number of pages11
JournalCatalysis Science and Technology
Volume7
Issue number17
DOIs
StatePublished - 2017

Bibliographical note

Funding Information:
We acknowledge support from the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award number DE-SC0001004.

Publisher Copyright:
© 2017 The Royal Society of Chemistry.

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