Adsorption and Reaction on Oxide Surfaces: CO and CO₂ on Cr₂O₃(111)

Abstract

We have investigated the adsorption of CO and CO2 on epitaxially grown Cr2O3(111) by means of EELS. LEED, ARUPS, NEXAFS and XPS. CO is found to adsorb on the oxide surface in an ordered (√3 × √3)R30° structure with the molecular axis oriented approximately parallel to the surface. CO2 on the other hand reacts with the chromium oxide to form a surface carbonate. Adsorption of CO, respectively reaction of CO2 only takes place on a clean, freshly flashed oxide surface. Preadsorption of oxygen leads to a surface which is rather inert to adsorption, likely due to electronic or steric reasons.

The Growth and Properties of Pd and Pt on Al2O3/NiAl(110)

“…This explanation is also corroborated by CO adsorption experiments on transition metal oxides which showed that desorption temperatures in the range between 150 K and 200 K are typical for these surfaces [17,18].…”

VAPOR-PHASE CATALYTIC CONVERSION OF ETHANOL INTO 1,3-BUTADIENE ON Cr-Ba/MCM-41 CATALYSTS

“…In previous studies, it was reported that CO 2 can be absorbed irreversibly on OH -groups (basic sites) producing CO 3 2-and H 2 O species [Cheng et al, 1998]. Therefore, an increase of the catalyst basicity can be assigned to the alkali-earth properties of barium [Yang and Kim, 2010;Zhang and Singh, 2008] and to the tendency to form carbonates on the chromium surfaces [Seiferth et al, 1999;Kuhlenbeck et al, 1992]. Figure 4 shows the IR transmission spectra of samples in the range 4000-400 cm -1…”

Structure of the α-Cr2O3(0001) surface: Anab initiototal

“…One surface that has been the subject of a number of studies is thin-film Cr 2 O 3 grown on Cr͑110͒. [2][3][4] However, the structure of this film is not clear, although on the basis of high-resolution electron-energy-loss spectroscopy on Al 2 O 3 films grown on NiAl͑110͒, a tentative assignment of the surface as the ␥ phase has been made. 5 The ␥ phase is a disordered phase in which the tetrahedral and octahedral holes in the oxygen lattice have fractional occupancy, 6 while the ␣ phase is a wellordered bulk crystal showing a corundum structure.…”