Acidity and catalytic activity of a nafion-H/silica nanocomposite catalyst compared with a silica-supported nafion sample

Béla Török, I. Kiricsi, Árpád Molnár, George A. Olah

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59 Citations (Scopus)

Abstract

Acid sites were characterized in the Nafion-H/silica nanocomposite catalyst through pyridine adsorption using the surface FTIR method. An impregnated Nafion-H/SiO2 catalyst was also studied for comparison. The ring-opening reaction of cyclopropane was used to characterize surface acidity. The 13% Nafion-H/silica nanocomposite sample had a large number of surface SO3H groups compared to the silica-supported Nafion-H; this guarantees excellent performance in catalytic transformations. This excellent activity was due to the increased accessibility of surface-active sites to reactants, made certain by the large surface area and the porous structure of the silica matrix. Pyridine adsorption data showed that the surface concentration of Broensted sites of the nanocomposite material was ~ 1 order of magnitude higher than that of the silica-supported sample. However, the difference in catalytic activity was more pronounced when the initial rates of the catalytic reactions were compared, indicating that the concentration of surface-active sites was not the sole factor determining catalytic activity. The higher accessibility of protic sites on the surface in the Fries rearrangement was possibly due to the experimental conditions and the favorable steric demand of the reacting molecule.

Original languageEnglish
Pages (from-to)132-138
Number of pages7
JournalJournal of Catalysis
Volume193
Issue number1
DOIs
Publication statusPublished - Jul 1 2000

Fingerprint

Acidity
acidity
Silicon Dioxide
catalytic activity
Catalyst activity
Nanocomposites
nanocomposites
Silica
silicon dioxide
catalysts
Catalysts
Pyridine
pyridines
Adsorption
cyclopropane
adsorption
perfluorosulfonic acid
acids
Molecules
Acids

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

Acidity and catalytic activity of a nafion-H/silica nanocomposite catalyst compared with a silica-supported nafion sample. / Török, Béla; Kiricsi, I.; Molnár, Árpád; Olah, George A.

In: Journal of Catalysis, Vol. 193, No. 1, 01.07.2000, p. 132-138.

Research output: Contribution to journalArticle

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