Frequency-response NH3 sorption study of acidic sites in H-ZSM-5 catalysts

G. Onyestyák, Dongmin Shen, Lovat V C Rees

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The frequency-response (FR) technique has been used to study the kinetics of ammonia adsorption-desorption processes and to characterise the acidic sites in two different, well characterised H-ZSM-5 catalysts. The FR method has been shown to be capable of distinguishing the different strengths and concentrations of acid sites using sorbate pressures close to those applied under real reaction conditions. The method, therefore, has advantages over techniques which require high vacuum or low probe molecule pressures to obtain relevant information. The FR observations were in agreement with the results of other examinations. Although in the range of this study the direct interaction between ammonia and the acidic sites can be detected most probably only above 623 K, the rate spectra of hydrogen-bonded ammonia sorption on ammonium ions seems to be characteristic for acidic catalysts. Adspecies detected by the FR technique must also play a role in any dynamic system of practical interest. Combination of the technique with other methods is suggested to obtain a more complete description of zeolitic acid sites.

Original languageEnglish
Pages (from-to)307-315
Number of pages9
JournalJournal of the Chemical Society - Faraday Transactions
Volume92
Issue number2
Publication statusPublished - Jan 21 1996

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sorption
frequency response
Frequency response
Sorption
Ammonia
catalysts
ammonia
Catalysts
sorbates
acids
Acids
high vacuum
Ammonium Compounds
Hydrogen
Desorption
Dynamical systems
examination
desorption
Vacuum
Ions

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Frequency-response NH3 sorption study of acidic sites in H-ZSM-5 catalysts. / Onyestyák, G.; Shen, Dongmin; Rees, Lovat V C.

In: Journal of the Chemical Society - Faraday Transactions, Vol. 92, No. 2, 21.01.1996, p. 307-315.

Research output: Contribution to journalArticle

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