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

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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.

Item Type: Article
Uncontrolled Keywords: Perovskite; PrMnO3+δ; silver; catalysis; CO Oxidation
Subjects: Materials Science
Depositing User: Dr. Nitin Labhasetwar
Date Deposited: 11 Jan 2018 06:56
Last Modified: 11 Jan 2018 06:56

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