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| Titel |
Comparative study of the effect of water on the heterogeneous reactions of carbonyl sulfide on the surface of α-Al2O3 and MgO |
| VerfasserIn |
Y. Liu, Q. Ma, H. He |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 16 ; Nr. 9, no. 16 (2009-08-31), S.6273-6286 |
| Datensatznummer |
250007599
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| Publikation (Nr.) |
 copernicus.org/acp-9-6273-2009.pdf |
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| Zusammenfassung |
| Here we compared the heterogeneous reactions of carbonyl
sulfide (OCS) on the surface of α-Al2O3 and MgO and the
effect of water on the reactions at 300 K using Knudsen cell–mass
spectrometry, diffuse reflectance infrared Fourier transform spectroscopy,
and temperature programmed reactions. H2S and CO2 were found to be
hydrolysis products of OCS on both α–Al2O3 and MgO at
ambient temperature. At low water vapor pressure (<6.8×10−6 Torr),
when water vapor pressure in the Knudsen cell reactor increased from
2.3×10−6 to 6.8×10−6 Torr, the initial true uptake
coefficient of OCS on α-Al2O3 decreased from
4.70±0.45×10−7 to 3.59±0.34×10−7; while it
increased from 5.19±0.49×10−7 to 6.48±0.62×10−7
on MgO under the same conditions. At high relative humidity
(0.07–0.67), the observed uptake coefficients of OCS on
α-Al2O3 and MgO, which were measured using an in situ DRIFTS, decreased
from 4.63±0.22×10−6 to 1.00±0.47×10−6
and from 9.72±0.46×10−5 to 7.68±0.36×10−5,
respectively, when RH increased from 0.07 to 0.67 corresponding to
1.7–15.9 Torr of water vapor pressure. In the RH region of 0.17–0.67, the
average observed uptake coefficient of OCS on α-Al2O3 and
MgO was equal to 8.34±2.19×10−7 and 8.19±0.48×10−5,
respectively. The restrictive effect of water on the
heterogeneous reaction of OCS on the surface of α-Al2O3
and MgO was found to be related to competitive adsorption between water
and OCS molecules; while the promotive effect of water on the heterogeneous
reaction of OCS on the surface of MgO at low coverage was ascribed to the
formation of surface hydroxyl groups. When the environmental RH was greater
than the RH of the monolayer, which occurred readily at the atmospherically
relevant humidity in the troposphere, thick water layer formed on the
mineral dusts, especially, the basic thick water layer formed on the basic
component of mineral dusts may be the primary contributor to the
heterogeneous hydrolysis of OCS in the troposphere. |
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