Oxidation of CO on surface hematite in high CO2 atmospheres

Grenfell, John Lee; Stock, Joachim; Patzer, A. B. C.; Gebauer, S; Rauer, H.

doi:10.1016/j.pss.2010.04.023

Cited by 6 publications

(3 citation statements)

References 45 publications

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“…Hematite is also found on Mars (Kula & Baldwin 2012), and is of interest in the study of the history of water on the planet. Also, it may be a component of exoplanetary atmospheres if their temperature allow its presence in solid form (Grenfell et al 2010). Clay flakes can be found on the surface of Mars (Roush & Orenberg 1996).…”

Section: Input Matricesmentioning

confidence: 99%

Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

Escobar-Cerezo

Palmer

Muñoz

et al. 2017

ApJ

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The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected to mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.

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Section: Input Matricesmentioning

confidence: 99%

Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

Escobar-Cerezo

Palmer

Muñoz

et al. 2017

ApJ

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“…Among all iron oxides, hematite is well known for its catalytic properties enabling to conduct efficiently the catalytic oxidation of CO to CO 2 [172,173]. It is believed [174] that even under the extra-terrestrial conditions, i.e., in hot, CO 2 -rich planetary atmospheres, such as Venus, oxidation of gaseous CO occurs on the surface of the mineral hematite Fe 2 O 3 .…”

Section: α-Fe 2 O 3 (Hematite)mentioning

confidence: 99%

Surface-Controlled Photocatalysis and Chemical Sensing of TiO2, α-Fe2O3, and Cu2O Nanocrystals

et al. 2019

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A relatively new approach to the design of photocatalytic and gas sensing materials is to use the shape-controlled nanocrystals with well-defined facets exposed to light or gas molecules. An abrupt increase in a number of papers on the synthesis and characterization of metal oxide semiconductors such as a TiO2, α-Fe2O3, Cu2O of low-dimensionality, applied to surface-controlled photocatalysis and gas sensing, has been recently observed. The aim of this paper is to review the work performed in this field of research. Here, the focus is on the mechanism and processes that affect the growth of nanocrystals, their morphological, electrical, and optical properties and finally their photocatalytic as well as gas sensing performance.

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“…However, CO oxidation can also occur 79 catalytically on a surface at high temperatures in the presence of O2, including the proposed 80 oxidation of CO on hematite at the Venusian surface (Grenfell et al, 2010;Grenfell et al, 81 2013). The oxidation can take place either through the Langmuir-Hinshelwood mechanism, 82 which involves both species adsorbing on the surface and then diffusing together before 83 reacting; or via the Eley-Rideal mechanism, where reaction occurs between one of the 84 reactants adsorbed on the surface and the second directly from the gas phase (Kolasinski, 85 2002).…”

Section: Co + So2  Co2+ So (R4) 77mentioning

confidence: 99%

CO oxidation and O2 removal on meteoric material in Venus’ atmosphere

Frankland

James

Carrillo‐Sánchez

et al. 2017

Icarus

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13The heterogeneous oxidation of CO by O2 on olivine, Fe sulfate and Fe oxide particles was 14 studied using a flow tube apparatus between 300 and 680 K. These particles were chosen as 15 possible analogues of unablated cosmic dust and meteoric smoke in V atmosphere. On 16 olivine and Fe oxides, the rate of CO oxidation to CO2 only becomes significant above 450 K. 17For iron sulfates, CO2 production was not observed until these dust analogues had 18 decomposed into iron oxides at ~ 540 K. The CO oxidation rate increases significantly with a 19 higher Fe content in the dust, implying that oxidation occurs through Fe active sites (no 20 reaction was observed on Mg2SiO4). The oxidation kinetics can be explained by CO reacting 21 with chemi-sorbed O2 through an Eley-Rideal mechanism, which is supported by electronic 22 structure calculations. Uptake coefficients were measured from 450 to 680 K, yielding: 23 2 log10( (CO on MgFeSiO4)) = (2.9 ± 0.1) × 10 -3 T(K) (8.2 ± 0.1); 24 log10( (CO on Fe2SiO4) = (2.3 ± 0.3) × 10 -3 T(K) (7.7 ± 0.2); 25 log10( (CO on FeOOH/Fe2O3) = (5.6 ± 0.8) × 10 -3 T(K) (9.3 ± 0.4). 26 A 1-D atmospheric model of Venus was then constructed to explore the role of heterogeneous 27 oxidation. The cosmic dust input to Venus, mostly originating from Jupiter Family Comets, is 28 around 32 tonnes per Earth day. A chemical ablation model was used to show that ~34% of 29 this incoming mass ablates, forming meteoric smoke particles which, together with unablated 30 dust particles, provide a significant surface for the heterogeneous oxidation of CO to CO2 in 31 V. This process should cause almost complete removal of O2 below 40 km, 32 but have a relatively small impact on the CO mixing ratio (since CO is in large excess over O2). 33Theoretical quantum calculations indicate that the gas-phase oxidation of CO by SO2 in the 34 lower troposphere is not competitive with the heterogeneous oxidation of CO. Finally, the 35 substantial number density of meteoric smoke particles predicted to occur above the cloud 36 tops may facilitate the low temperature heterogeneous chemistry of other species. 37 38

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Oxidation of CO on surface hematite in high CO2 atmospheres

Cited by 6 publications

References 45 publications

Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

Surface-Controlled Photocatalysis and Chemical Sensing of TiO2, α-Fe2O3, and Cu2O Nanocrystals

CO oxidation and O2 removal on meteoric material in Venus’ atmosphere

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