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Direct observation of catalytic oxidation of particulate matter using in situ TEM.

Kamatani K, Higuchi K, Yamamoto Y, Arai S, Tanaka N, Ogura M - Sci Rep (2015)

Bottom Line: Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction.In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction.Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Institute of Industrial Science, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo 153-8505, Japan.

ABSTRACT
The ability to observe chemical reactions at the molecular level convincingly demonstrates the physical and chemical phenomena occurring throughout a reaction mechanism. Videos obtained through in situ transmission electron microscopy (TEM) revealed the oxidation of catalytic soot under practical reaction conditions. Carbon oxidation reactions using Ag/SiO2 or Cs2CO3/nepheline catalysts were performed at 330 °C under an O2 flow of 0.5 Pa in the TEM measurement chamber. Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction. In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction. Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms.

No MeSH data available.


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Catalytic performance of carbon oxidation. Ag/SiO2 (red line), Cs2CO3/nepheline (blue line), and nepheline (green line). The black line is carbon oxidation without catalyst (noncontact oxidation by gaseous oxygen).
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f1: Catalytic performance of carbon oxidation. Ag/SiO2 (red line), Cs2CO3/nepheline (blue line), and nepheline (green line). The black line is carbon oxidation without catalyst (noncontact oxidation by gaseous oxygen).

Mentions: The catalytic performance of carbon oxidation is shown in Fig. 1. Nepheline and SiO2 (not shown in the figure) showed next to no catalytic activity for the oxidation because their DTA curves closely resemble those of the noncatalytic reaction of carbon with gaseous oxygen. The carbon oxidation using Ag/SiO2 and Cs2CO3/nepheline occurred at 255 °C and 311 °C, respectively, indicating that the Ag catalyst shows a higher oxidation activity than the Cs2CO3 catalyst.


Direct observation of catalytic oxidation of particulate matter using in situ TEM.

Kamatani K, Higuchi K, Yamamoto Y, Arai S, Tanaka N, Ogura M - Sci Rep (2015)

Catalytic performance of carbon oxidation. Ag/SiO2 (red line), Cs2CO3/nepheline (blue line), and nepheline (green line). The black line is carbon oxidation without catalyst (noncontact oxidation by gaseous oxygen).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4495604&req=5

f1: Catalytic performance of carbon oxidation. Ag/SiO2 (red line), Cs2CO3/nepheline (blue line), and nepheline (green line). The black line is carbon oxidation without catalyst (noncontact oxidation by gaseous oxygen).
Mentions: The catalytic performance of carbon oxidation is shown in Fig. 1. Nepheline and SiO2 (not shown in the figure) showed next to no catalytic activity for the oxidation because their DTA curves closely resemble those of the noncatalytic reaction of carbon with gaseous oxygen. The carbon oxidation using Ag/SiO2 and Cs2CO3/nepheline occurred at 255 °C and 311 °C, respectively, indicating that the Ag catalyst shows a higher oxidation activity than the Cs2CO3 catalyst.

Bottom Line: Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction.In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction.Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Institute of Industrial Science, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo 153-8505, Japan.

ABSTRACT
The ability to observe chemical reactions at the molecular level convincingly demonstrates the physical and chemical phenomena occurring throughout a reaction mechanism. Videos obtained through in situ transmission electron microscopy (TEM) revealed the oxidation of catalytic soot under practical reaction conditions. Carbon oxidation reactions using Ag/SiO2 or Cs2CO3/nepheline catalysts were performed at 330 °C under an O2 flow of 0.5 Pa in the TEM measurement chamber. Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction. In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction. Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms.

No MeSH data available.


Related in: MedlinePlus