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Effects of surface and bulk silver on PrMnO3+# perovskite for CO and soot oxidation: Experimental evidences for the chemical state of silver

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Title Effects of surface and bulk silver on PrMnO3+# perovskite for CO and
soot oxidation: Experimental evidences for the chemical state of silver
 
Creator Megarajan, Suresh Kumar
Rayalu, Sadhana
Nishibori, Maiko
Teraoka, Yasutake
Labhsetwar, Nitin
 
Subject Materials Science
 
Description Unambiguous evidences have been obtained to explain the presence and effects of both
framework and extra-framework silver on catalytic properties of Pr(Ag)MnO3+δ perovskite type
materials, using various tools such as XPS, HR-TEM, O2-TPD and H2-TPR analysis. Three types
of Ag incorporated PrMnO3 perovskite samples were synthesized by means of Ag partial
substitution in perovskite lattice and Ag dispersion on the surface of the synthesized perovskite
phase, using two different calcination temperatures of 200 °C and 550 °C. The amount of silver
used was 1 wt% (0.000225 mol), in all the three catalysts. Based on extensive characterization
studies, it was clearly explained that the partially substituted Ag for Pr is present in the lattice
along with Pr at ‘A’ site of ABO3 perovskite structure. Ag surface incorporated PrMnO3+δ
sample calcined at 550 °C shows both surface metallic silver as well as partially substituted Ag
in perovskite lattice, while Ag2O nanoparticles were observed on surface in case of another
sample calcined at 200 °C. All the synthesized materials were evaluated for their CO and soot
oxidation activity, considering the renewed interest in Ag promoted catalytic materials, and
ambiguity about its location in perovskite strcuture as well as its role in promoting catalytic and
other properties of perovskite type materials. Perovskites with surface Ag species show better
catalytic activity than Ag substituted counterpart. This improved and better activity of Ag
dispersed samples was because of the presence of surface active redox couple of Ag/Ag2O,
which facilitates surface redox reaction pathway of CO and soot oxidation reactions.
 
Publisher American Chemical Society
 
Date 2015
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://neeri.csircentral.net/1079/1/megarajan2014.pdf
Megarajan, Suresh Kumar and Rayalu, Sadhana and Nishibori, Maiko and Teraoka, Yasutake and Labhsetwar, Nitin (2015) Effects of surface and bulk silver on PrMnO3+# perovskite for CO and soot oxidation: Experimental evidences for the chemical state of silver. ACS catalysis, 5 (1). pp. 301-309. ISSN 2155-5435
 
Relation http://neeri.csircentral.net/1079/