2018-Sustainable Industrial Processing Summit
SIPS2018 Volume 8. Composite, Ceramic, Nanomaterials and Mathematics
| Editors: | F. Kongoli, M. de Campos |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2018 |
| Pages: | 184 pages |
| ISBN: | 978-1-987820-96-6 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Enhanced Precious Metal-free LaCo<sub>x</sub>Mn<sub>1-x</sub>O<sub>3</sub> Hybrid Perovskite Catalysts with Fine-Tunable Redox Properties
Emrah Ozensoy1;1BILKENT UNIVERSITY, Ankara, Turkey;
Type of Paper: Regular
Id Paper: 221
Topic: 18
Abstract:
Simple (LaMnO<sub>3</sub> and LaCoO<sub>3</sub>) and complex hybrid perovskites (LaCo<sub>x</sub>Mn<sub>1-x</sub>O<sub>3</sub>) were synthesized, and their catalytic functionality and thermal/chemical durability were investigated in a comparative manner. Structural properties as well as catalytic behavior of these hybrid perovskite structures were examined comprehensively, using a multitude of in-situ and ex-situ characterization techniques such as XRD, BET, TEM-EDX, STEM, ICP-MS, TPR, and ex-situ and in-situ XANES, and were compared to that of LaMnO<sub>3</sub> and LaCoO<sub>3</sub> benchmark systems. Adsorption and desorption properties of NOx species examined by in-situ FTIR and TPD revealed a superior NOx storage capacity (NSC) and thermal stability for LaCo<sub>0.7</sub>Mn<sub>0.3</sub>O<sub>3</sub> and LaCo<sub>0.8</sub>Mn<sub>0.2</sub>O<sub>3</sub> hybrid perovskites as compared to that of LaMnO<sub>3</sub> and LaCoO<sub>3</sub>.TPR and in-situ XANES results suggested that Mn addition enhances thermal stability by suppressing the sintering of Co at high temperatures and enhances NOx storage by increasing the number of NOx adsorption sites. Ex-situ XANES and XPS results suggested that Mn addition alters the oxidation state of Mn and Co via Mn<sup>3+</sup>+ Co<sup>3+</sup> -> Mn<sup>4+</sup> +Co<sup>2+</sup> leading to a stoichiometrically defective but functionally enhanced structure. Hybrid perovskites were also found to facilitate N-O bond activation. NOx TPD results point out that treatment with H<sub>2</sub>(g) further enhances the NSC of hybrid perovskites due to the formation of oxygen vacancies and OH<sup>-</sup> radicals. These results suggest that B-site cations of perovskites play a crucial role both in catalytic activity and stability. Current findings reveal valuable molecular-level insights regarding the origins of the fine-tunable redox/catalytic behavior of mixed perovskite systems, which could be applicable to a large variety of catalytic systems to enhance catalytic activity, structural durability, and selectivity.
Keywords:
Characterization; Energy; Materials; Nanomaterials; Nanoparticles; NearEdge; Spectroscopy; Sustainability; Synthesis;References:
[1] K. E. Ercan, Z. Say, M. Kurt, M. Karatok, G. Pantaleo, L., F. Liotta, E. Ozensoy, submitted (2018)[2] Z. Say, Z., M. Dogac, E. I. Vovk, Y. E. Kalay, C. H. Kim, W. Li, E. Ozensoy, Applied Catalysis B: Environmental, 154-155 (2014) 51.
[3] M. Kurt, Z. Say, K. E. Ercan, E. I. Vovk, C. H. Kim, E. Ozensoy, Topics in Catalysis, 60 1-2 (2017) 40.