Adsorption dynamics and kinetics of CO₂ on Fe/FeO_x nanoclusters supported on HOPG

Abstract

The adsorption dynamics and kinetics of CO 2 on FeO x clusters have been studied using thermal desorption spectroscopy (TDS) and molecular beam scattering. According to AES data, even at good vacuum conditions, the vapor-deposited Fe clusters oxidize readily. An ensemble of metallic and oxidized Fe clusters form. Three structures at 120 K, 160 K, and 500 K are seen in CO 2 TDS, which are assigned to physisorbed CO 2 and carbonate decomposition. The latter structure is only present for large Fe exposures, χ Fe . The initial adsorption probabilities, S 0 , decrease with increasing impact energy. S 0 increases with adsorption temperature, T s , which is discussed in the framework of the capture-zone model (CZM). Small effects of the cluster size on the initial adsorption probabilities, S 0 , as well as its coverage dependence, S( ), have been seen. The coverage dependence of the adsorption probabilities obeys the Kisliuk precursor model, as predicted by the CZM.

Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

“…[16] Among a variety of materials reported in this category, this section describes in detail adsorption on a representative oxide, calcium oxide, along with a discussion of other important metal-based adsorbents including magnesium oxides and lithium zirconates. Although we focus attention here on calcium oxides and magnesium oxides, it should be noted that many other metal oxides display some CO 2 adsorption properties under selected conditions including lithium oxides, [98] sodium oxides, [99][100][101][102] potassium oxides, [103,104] rubidium oxides, [105] cesium oxides, [106] barium oxides, [107] iron oxides, [108][109][110][111][112] tantalum oxides, [113] copper oxides, [114,115] chromium oxides, [116][117][118][119][120] and aluminum oxides. [121][122][123][124][125][126] where M can be, for example, Mg, Ca, Sr, Ba.…”

A multi-technique study of CO2 adsorption on Fe3O4 magnetite

“…14 To date there are no investigations of CO 2 adsorption on well-defined iron-oxide surfaces, despite the important role of these materials in both geochemistry and catalysis. Work on polycrystalline Fe 3 O 4 , 15 Fe 3 O 4 nanoparticles, 16 and FeO x nanoclusters on graphite 17 suggests however that both physisorption and carbonate formation can a) E-mail address: parkinson@iap.tuwien.ac.at occur, with stronger binding linked to the presence of Fe 2+ cations. 18,19 Very recent density functional theory (DFT) calculations based on the Fe 3 O 4 (111) surface suggest that CO 2 chemisorption can occur at undercoordinated oxygen sites and that this surface can activate CO 2 for hydrogenation.…”

Adsorption of CO2 by iron-exchanged heteropolyacid Fe1.5PMo12O40 supported on mesoporous cellular foams

“…The affinity of metallic oxides for the CO 2 and the carbonate formation principally depend of the strength and number of basic sites at their surface and varies as following: basic oxides [ amphoteric oxides [ acidic oxides [44,45]. A recent report on CO 2 adsorption using hydroxylated iron oxide nanoparticles [46,47] and iron oxide nanoclusters supported on HOPG [48] suggested that iron oxides and iron-based complexes can act as good adsorbents of CO 2 due to the affinity of iron toward the polarized CO 2 molecules, especially in complexes in which the iron center is present in a reduced state (Fe 2? ).…”