Propene oxidation over Cu[sub 2]O single-crystal surfaces: A surface science study of propene activation at 1 atm and 300 K

Propene oxidation was studied on Cu[sub 2]O single-crystal surfaces using XPS and TDS in ultrahigh vacuum (UHV) following propene exposures at 300 K and atmospheric pressure. Three different Cu[sub 2]O surfaces were examined: A Cu[sup +]-terminated (100) surface, an oxygen-terminated (100) surface,...

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Bibliographic Details
Published inJournal of catalysis Vol. 143:2
Main Authors Schulz, K.H., Cox, D.F.
Format Journal Article
LanguageEnglish
Published United States 01.10.1993
Subjects
10 SYNTHETIC FUELS
100200 - Synthetic Fuels- Production- (1990-)
400201 - Chemical & Physicochemical Properties
ALKENES
CATALYSIS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL ACTIVATION
CHEMICAL REACTIONS
COPPER COMPOUNDS
COPPER OXIDES
ELECTRON SPECTROSCOPY
HETEROGENEOUS CATALYSIS
HYDROCARBONS
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MILLER INDICES
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PROPYLENE
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
X-RAY SPECTROSCOPY
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Summary:Propene oxidation was studied on Cu[sub 2]O single-crystal surfaces using XPS and TDS in ultrahigh vacuum (UHV) following propene exposures at 300 K and atmospheric pressure. Three different Cu[sub 2]O surfaces were examined: A Cu[sup +]-terminated (100) surface, an oxygen-terminated (100) surface, and a (111) surface with accessible copper cations and lattice oxygen. Selective oxidation to acrolein is promoted by coordinately unsaturated surface lattice oxygen. No clear correlation between the formation of partial oxidation products and oxygen coordination was observed. Both selective and nonselective oxidation products are formed from lattice oxygen. The propene oxidation pathway proceeds through an allyloxy (CH[sub 2][double bond]CHCH[sub 2]O-) species where oxygen insertion occurs prior to the second hydrogen abstraction over Cu[sub 2]O. This conclusion was reached by comparing the propene TDS results from atmospheric pressure exposures with UHV allyl alcohol and acrolein thermal desorption data. The selective oxidation process over Cu[sub 2]O is subject to a [open quotes]pressure gap[close quotes] at 300 K with oxygen insertion occurring at higher pressures, presumably because of translational and collisional activation. However, the subsequent steps in the selective oxidation pathway can be effectively modeled by dissociative adsorption of oxygenates under UHV to simulate the oxygenated surface intermediates. 34 refs., 8 figs., 1 tab.
ISSN:0021-9517
1090-2694
DOI:10.1006/jcat.1993.1290