Surface composition and possible rearrangement of disperse Pt and Rh catalysts

Does the presence of carbon and oxygen contribute to different catalytic properties?

U. Wild, D. Teschner, R. Schlögl, Z. Paál

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The surface composition of Rh and Pt blacks (as determined by XPS) shows carbon and oxygen impurities in the untreated state. Oxygen on Pt is present as adsorbed O as well as OH/H2O groups and oxidized carbon. Rh was partly oxidized to Rr2C3, in agreement with UPS showing hardly any Fermi-edge intensity in untreated Rh as opposed to untreated Pt. High Fermi-edge intensities indicated a predominant metallic surface after an in situ treatment with H2 at 483 K, increasing the purity (XPS) to ∼90%. This treatment reduced Rh to metal and removed its C impurity. Pt, in turn, retained much carbon after H2 treatment, present mainly as graphitic carbon. A minor amount of CO was also detected, some of the O 1s peak belonging to it. The two metals were tested in methylcyclopentane reactions. Considering the necessity of carbon for nondegradative reactions and oxygen enhancing fragmentation, a correlation is suggested between the typical impurities of Pt and Rh and their respective catalytic propensities: the high fragmentation activity of Rh and the predominant nondegradative reactions to C6 "ring opening products" on Pt.

Original languageEnglish
Pages (from-to)93-98
Number of pages6
JournalCatalysis Letters
Volume67
Issue number2-4
Publication statusPublished - Jul 2000

Fingerprint

Surface structure
Carbon
Oxygen
catalysts
Catalysts
carbon
oxygen
Impurities
impurities
fragmentation
X ray photoelectron spectroscopy
Metals
Carbon Monoxide
metals
purity
rings
products

Keywords

  • Methylcyclopentane
  • Platinum black
  • Rhodium black
  • Surface carbon
  • Surface oxygen

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

Cite this

Surface composition and possible rearrangement of disperse Pt and Rh catalysts : Does the presence of carbon and oxygen contribute to different catalytic properties? / Wild, U.; Teschner, D.; Schlögl, R.; Paál, Z.

In: Catalysis Letters, Vol. 67, No. 2-4, 07.2000, p. 93-98.

Research output: Contribution to journalArticle

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AU - Paál, Z.

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N2 - The surface composition of Rh and Pt blacks (as determined by XPS) shows carbon and oxygen impurities in the untreated state. Oxygen on Pt is present as adsorbed O as well as OH/H2O groups and oxidized carbon. Rh was partly oxidized to Rr2C3, in agreement with UPS showing hardly any Fermi-edge intensity in untreated Rh as opposed to untreated Pt. High Fermi-edge intensities indicated a predominant metallic surface after an in situ treatment with H2 at 483 K, increasing the purity (XPS) to ∼90%. This treatment reduced Rh to metal and removed its C impurity. Pt, in turn, retained much carbon after H2 treatment, present mainly as graphitic carbon. A minor amount of CO was also detected, some of the O 1s peak belonging to it. The two metals were tested in methylcyclopentane reactions. Considering the necessity of carbon for nondegradative reactions and oxygen enhancing fragmentation, a correlation is suggested between the typical impurities of Pt and Rh and their respective catalytic propensities: the high fragmentation activity of Rh and the predominant nondegradative reactions to C6 "ring opening products" on Pt.

AB - The surface composition of Rh and Pt blacks (as determined by XPS) shows carbon and oxygen impurities in the untreated state. Oxygen on Pt is present as adsorbed O as well as OH/H2O groups and oxidized carbon. Rh was partly oxidized to Rr2C3, in agreement with UPS showing hardly any Fermi-edge intensity in untreated Rh as opposed to untreated Pt. High Fermi-edge intensities indicated a predominant metallic surface after an in situ treatment with H2 at 483 K, increasing the purity (XPS) to ∼90%. This treatment reduced Rh to metal and removed its C impurity. Pt, in turn, retained much carbon after H2 treatment, present mainly as graphitic carbon. A minor amount of CO was also detected, some of the O 1s peak belonging to it. The two metals were tested in methylcyclopentane reactions. Considering the necessity of carbon for nondegradative reactions and oxygen enhancing fragmentation, a correlation is suggested between the typical impurities of Pt and Rh and their respective catalytic propensities: the high fragmentation activity of Rh and the predominant nondegradative reactions to C6 "ring opening products" on Pt.

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