Highly active behaviour of nanocrystalline Co3O4 from oxalate nanorods in the oxidation of chlorinated short chain alkanes

Several bulk Co3O4 were prepared from various synthesis routes including direct calcination of a cobalt salt, grinding followed by solid-state reaction and thermal decomposition of cobalt oxalate nanorods. The resulting oxides were examined in the gas-phase oxidation of a model chlorinated short chain alkane namely, 1,2-dichloroethane. The route based on cobalt oxalate nanorods allowed to obtain high surface Co3O4 nanoparticles with a crystallite size as low as 13 nm, which exhibited both enhanced reducibility and oxygen uptake capacity at low temperatures when compared with the other prepared Co3O4 samples. As a result, this nanosized oxide converted the chlorinated feed at the lowest temperatures with an excellent selectivity to CO2. Conversion to deep oxidation products was complete (CO2, HCl and Cl2), and no appreciable deactivation was noticed. For all the cobalt catalysts tested, the conversion vs. temperature plot was well described by a first order reaction, and the data were therefore fitted to obtain the activation energy and pre-exponential factors.

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► Co3O4 synthesised via oxalate nanorods was highly active in the oxidation of 1,2-dichloroethane.
► An increase of activity with increasing surface area and decreasing crystallite size was found.
► Small crystallites led to the formation of easily reducible, highly active catalysts.
► The reaction was first-order in 1,2-dichloroethane with an activation energy of 55 kJ mol−1.