CARBON CARBON BOND FORMATION ON METAL-OXIDES - FROM SINGLE-CRYSTALS TOWARD CATALYSIS

Hicham Idriss, M LIBBY, M A BARTEAU

Research output: Contribution to journalArticle

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Abstract

Previous work in our laboratory indicated that carbonyl metathesis of aldehydes can be accomplished as a gas-solid reaction on a reduced TiO2(001) single crystal under ultrahigh vacuum (UHV). This reaction requires the presence of cations in lower oxidation states on the surface, but does not require Ti0 as suggested by previous studies in the liquid phase. In the course of attempts to carry out this reaction catalytically, TPD experiments on TiO2 single crystals and powders were conducted. In addition to the aldolization of acetaldehyde to crotonaldehyde, carbonyl metathesis of acetaldehyde to butene was observed. Benzaldehyde TPD on reduced TiO2 powder gave substantial amounts of styrene (PhCH=CH2) which is most likely formed by disproportionation of stilbene (PhCH=CHPh), the metathesis product observed in single crystal studies. Addition of Ti metal to titania resulted in the formation of large amounts of toluene (by unimolecular reduction) rather than stilbene or styrene (by bimolecular reductive coupling). More importantly, it was possible to form 1-phenylpropene (PhCH=CH-CH3), a cross-coupling product, by the co-metathesis of benzaldehyde and acetaldehyde on reduced titania, ceria and iron oxide powders during TPD at atmospheric pressure. These studies represent an extension of stoichiometric reactions observed on single crystals in UHV toward novel catalysis. While carbonyl metathesis has still not been accomplished catalytically, its observation during TPD of aldehydes on dihydrogen-reduced oxides has demonstrated the feasibility of each of the steps required to close a catalytic cycle.

Original languageEnglish
Pages (from-to)13-23
Number of pages11
JournalCatalysis Letters
Volume15
Issue number1-2
DOIs
Publication statusPublished - 1992

Keywords

  • REDUCTIVE COUPLING
  • ALDEHYDES
  • OLEFINS
  • CARBONYL METATHESIS
  • METAL OXIDE CATALYSTS
  • TIO2(001) SURFACE
  • PD(111) SURFACE
  • DECOMPOSITION
  • ACETYLENE
  • CHEMISTRY
  • ETHYLENE
  • TITANIUM
  • TIO2

Cite this

CARBON CARBON BOND FORMATION ON METAL-OXIDES - FROM SINGLE-CRYSTALS TOWARD CATALYSIS. / Idriss, Hicham; LIBBY, M ; BARTEAU, M A .

In: Catalysis Letters, Vol. 15, No. 1-2, 1992, p. 13-23.

Research output: Contribution to journalArticle

Idriss, Hicham ; LIBBY, M ; BARTEAU, M A . / CARBON CARBON BOND FORMATION ON METAL-OXIDES - FROM SINGLE-CRYSTALS TOWARD CATALYSIS. In: Catalysis Letters. 1992 ; Vol. 15, No. 1-2. pp. 13-23.
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abstract = "Previous work in our laboratory indicated that carbonyl metathesis of aldehydes can be accomplished as a gas-solid reaction on a reduced TiO2(001) single crystal under ultrahigh vacuum (UHV). This reaction requires the presence of cations in lower oxidation states on the surface, but does not require Ti0 as suggested by previous studies in the liquid phase. In the course of attempts to carry out this reaction catalytically, TPD experiments on TiO2 single crystals and powders were conducted. In addition to the aldolization of acetaldehyde to crotonaldehyde, carbonyl metathesis of acetaldehyde to butene was observed. Benzaldehyde TPD on reduced TiO2 powder gave substantial amounts of styrene (PhCH=CH2) which is most likely formed by disproportionation of stilbene (PhCH=CHPh), the metathesis product observed in single crystal studies. Addition of Ti metal to titania resulted in the formation of large amounts of toluene (by unimolecular reduction) rather than stilbene or styrene (by bimolecular reductive coupling). More importantly, it was possible to form 1-phenylpropene (PhCH=CH-CH3), a cross-coupling product, by the co-metathesis of benzaldehyde and acetaldehyde on reduced titania, ceria and iron oxide powders during TPD at atmospheric pressure. These studies represent an extension of stoichiometric reactions observed on single crystals in UHV toward novel catalysis. While carbonyl metathesis has still not been accomplished catalytically, its observation during TPD of aldehydes on dihydrogen-reduced oxides has demonstrated the feasibility of each of the steps required to close a catalytic cycle.",
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AU - Idriss, Hicham

AU - LIBBY, M

AU - BARTEAU, M A

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N2 - Previous work in our laboratory indicated that carbonyl metathesis of aldehydes can be accomplished as a gas-solid reaction on a reduced TiO2(001) single crystal under ultrahigh vacuum (UHV). This reaction requires the presence of cations in lower oxidation states on the surface, but does not require Ti0 as suggested by previous studies in the liquid phase. In the course of attempts to carry out this reaction catalytically, TPD experiments on TiO2 single crystals and powders were conducted. In addition to the aldolization of acetaldehyde to crotonaldehyde, carbonyl metathesis of acetaldehyde to butene was observed. Benzaldehyde TPD on reduced TiO2 powder gave substantial amounts of styrene (PhCH=CH2) which is most likely formed by disproportionation of stilbene (PhCH=CHPh), the metathesis product observed in single crystal studies. Addition of Ti metal to titania resulted in the formation of large amounts of toluene (by unimolecular reduction) rather than stilbene or styrene (by bimolecular reductive coupling). More importantly, it was possible to form 1-phenylpropene (PhCH=CH-CH3), a cross-coupling product, by the co-metathesis of benzaldehyde and acetaldehyde on reduced titania, ceria and iron oxide powders during TPD at atmospheric pressure. These studies represent an extension of stoichiometric reactions observed on single crystals in UHV toward novel catalysis. While carbonyl metathesis has still not been accomplished catalytically, its observation during TPD of aldehydes on dihydrogen-reduced oxides has demonstrated the feasibility of each of the steps required to close a catalytic cycle.

AB - Previous work in our laboratory indicated that carbonyl metathesis of aldehydes can be accomplished as a gas-solid reaction on a reduced TiO2(001) single crystal under ultrahigh vacuum (UHV). This reaction requires the presence of cations in lower oxidation states on the surface, but does not require Ti0 as suggested by previous studies in the liquid phase. In the course of attempts to carry out this reaction catalytically, TPD experiments on TiO2 single crystals and powders were conducted. In addition to the aldolization of acetaldehyde to crotonaldehyde, carbonyl metathesis of acetaldehyde to butene was observed. Benzaldehyde TPD on reduced TiO2 powder gave substantial amounts of styrene (PhCH=CH2) which is most likely formed by disproportionation of stilbene (PhCH=CHPh), the metathesis product observed in single crystal studies. Addition of Ti metal to titania resulted in the formation of large amounts of toluene (by unimolecular reduction) rather than stilbene or styrene (by bimolecular reductive coupling). More importantly, it was possible to form 1-phenylpropene (PhCH=CH-CH3), a cross-coupling product, by the co-metathesis of benzaldehyde and acetaldehyde on reduced titania, ceria and iron oxide powders during TPD at atmospheric pressure. These studies represent an extension of stoichiometric reactions observed on single crystals in UHV toward novel catalysis. While carbonyl metathesis has still not been accomplished catalytically, its observation during TPD of aldehydes on dihydrogen-reduced oxides has demonstrated the feasibility of each of the steps required to close a catalytic cycle.

KW - REDUCTIVE COUPLING

KW - ALDEHYDES

KW - OLEFINS

KW - CARBONYL METATHESIS

KW - METAL OXIDE CATALYSTS

KW - TIO2(001) SURFACE

KW - PD(111) SURFACE

KW - DECOMPOSITION

KW - ACETYLENE

KW - CHEMISTRY

KW - ETHYLENE

KW - TITANIUM

KW - TIO2

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DO - 10.1007/BF00770894

M3 - Article

VL - 15

SP - 13

EP - 23

JO - Catalysis Letters

JF - Catalysis Letters

SN - 1011-372X

IS - 1-2

ER -