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|Title:||In-situ generation of maximum trivalent cobalt in synthesis of hydrotalcite-like compounds Mg(x)Co(II)(1-x-y)Co(III)(y)(OH)2(NO3)(y)·nH2O|
|Authors:||Xu, Z.P. |
|Citation:||Xu, Z.P., Zeng, H.C. (2000). In-situ generation of maximum trivalent cobalt in synthesis of hydrotalcite-like compounds Mg(x)Co(II)(1-x-y)Co(III)(y)(OH)2(NO3)(y)·nH2O. Chemistry of Materials 12 (9) : 2597-2603. ScholarBank@NUS Repository. https://doi.org/10.1021/cm000053f|
|Abstract:||In-situ generation of trivalent cobalt cations has been investigated for the hydrotalcite-like compounds Mg(x)Co(II)(1-x-y)Co(III)(y)(OH)2(NO3)(y)·nH2O at 25-40 °C under oxygen-containing atmospheres. It is noted that with more involvement of Mg2+ in the compounds, less Co2+ cations are needed to maintain the hydrotalcite-like structure. Because of the presence of the Mg2+, more Co2+ can be oxidized under the current experimental conditions and the highest mole ratios of Co3+ to total cobalt cations (Co3+:Co) observed in this work is 57%. The mole ratio of Co3+ to total metal cations (Co3+:(Mg+Co)) achieved in this work is 31% after 4 days of oxidation reaction, which is close to its upper charge limit to produce a single-phase hydrotalcite-like structure (33%). Two major thermal events are observed when the compounds are heated. The first one at 113-134 °C is attributed to the removal of interlayer water molecules while the second at 274-333 °C to the dehydroxylation and decomposition of intercalated anions. Higher catalytic activity for nitrous oxide (N2O) decomposition is observed for the Mg-Co oxides with the same cobalt content but lower mole ratios of Co3+: Co in their hydrotalcite-like precursors. The reason for this activity variation has also been addressed.|
|Source Title:||Chemistry of Materials|
|Appears in Collections:||Staff Publications|
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