Evolution of the catalytic activity in Pt/sulfated zirconia catalysts: Structure, composition, and catalytic properties of the catalyst precursor and the calcined catalyst

Jean Marie Manoli, Claude Potvin, Martin Muhler, Ute Wild, Gábor Resofszki, Thomas Buchholz, Z. Paál

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

A 3% Pt/sulfated zirconia catalyst was prepared and characterized before and after calcination at 900 K by XRD, XPS, EM, and in the catalytic hydroisomerization of n-hexane. The "fresh" sample exhibited small but definite catalytic properties. Calcination brought about a dramatic increase of the activity with practically constant high (90-100%) selectivity for hydroisomerization versus cracking. This increased activity was accompanied by the transformation of the predominantly amorphous support to predominantly tetragonal crystals and the wrapping up of most parts of surface Pt atoms into the bulk, as shown by the physical characterization methods. Hence metallic Pt particles exhibited mainly Pt-O rather than Pt-S interactions. S was present as sulfate. Pt-sulfated zirconia was different from traditional bifunctional metal catalysts on acidic supports. We attributed its higher catalytic activity and favorable isomerization selectivity to a few but very active centers, formed by interaction of Pt sites with sulfate groups on the high Miller-index surfaces of ZrO2. Calcination must be essential to create these active sites. H2 dissociating on Pt sites would provide the hydride species that are necessary for isomerization occurring on the acidic (sulfate-zirconia) part of that ensemble. We proposed the name "compressed bifunctional sites" for these centers of acid-metal cooperation. The assumption of such active sites, the maximum activity as a function of the hydrogen pressure, can also be explained in a consistent way.

Original languageEnglish
Pages (from-to)338-351
Number of pages14
JournalJournal of Catalysis
Volume178
Issue number1
Publication statusPublished - 1998

Fingerprint

zirconium oxides
Zirconia
Calcination
roasting
Sulfates
catalytic activity
sulfates
Catalyst activity
Isomerization
catalysts
isomerization
Catalysts
selectivity
Metals
Chemical analysis
Catalyst selectivity
Hexane
Catalyst supports
Hydrides
metals

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

Evolution of the catalytic activity in Pt/sulfated zirconia catalysts : Structure, composition, and catalytic properties of the catalyst precursor and the calcined catalyst. / Manoli, Jean Marie; Potvin, Claude; Muhler, Martin; Wild, Ute; Resofszki, Gábor; Buchholz, Thomas; Paál, Z.

In: Journal of Catalysis, Vol. 178, No. 1, 1998, p. 338-351.

Research output: Contribution to journalArticle

Manoli, Jean Marie ; Potvin, Claude ; Muhler, Martin ; Wild, Ute ; Resofszki, Gábor ; Buchholz, Thomas ; Paál, Z. / Evolution of the catalytic activity in Pt/sulfated zirconia catalysts : Structure, composition, and catalytic properties of the catalyst precursor and the calcined catalyst. In: Journal of Catalysis. 1998 ; Vol. 178, No. 1. pp. 338-351.
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