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Mg and Al substituted cobalt spinels as catalysts for low temperature deN sub(2)O-Evidence for octahedral cobalt active sites
A series of cobalt spinel oxides with the chemical composition: Co sub(3)O sub(4), MgCo sub(2)O sub(4), MgCoAlO sub(4), CoAl sub(2)O sub(4), Mg sub(0.5)Co sub(0.5)Al sub(2)O sub(4) and MgAl sub(2)O sub(4) was synthesised, characterised and studied for catalytic decomposition of N sub(2)O. Selective...
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Published in: | Applied catalysis. B, Environmental Environmental, 2014-03, Vol.146, p.105-111 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | A series of cobalt spinel oxides with the chemical composition: Co sub(3)O sub(4), MgCo sub(2)O sub(4), MgCoAlO sub(4), CoAl sub(2)O sub(4), Mg sub(0.5)Co sub(0.5)Al sub(2)O sub(4) and MgAl sub(2)O sub(4) was synthesised, characterised and studied for catalytic decomposition of N sub(2)O. Selective replacement of cobalt ions in the tetrahedral and octahedral sites was employed to probe the specific activity of both types of centres. The combined experimental XRD, UV-vis, RS, XPS, BET, TPR, Temperature Programmed Catalytic Reaction (TPCatR) methods and DFT modelling allowed to explore the mechanistic role of the coordination (tetrahedral, octahedral) and valence (+2, +3) states of cobalt ions in the Co sub(3)O sub(4) spinel matrix. The prime active sites of deN sub(2)O reaction were definitely identified as the octahedral Co super(3+) ions (E sub(a) = 15-17 kcal mob super(-1)), whereas the tetrahedral Co super(2+) ions were found to be clearly much less active (E sub(a) = 27-28 kcal mol super(-1)). |
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ISSN: | 0926-3373 |
DOI: | 10.1016/j.apcatb.2013.05.027 |