Scientists at Los Alamos National Laboratory (LANL) report that cobalt holds promise as an industrial catalyst with potential applications in such energy-related technologies such as the production of biofuels and the reduction of carbon dioxide—if the cobalt is captured in a complex molecule so that it mimics the precious metals that normally serve this industrial role.
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In work published in the international edition of the chemistry journal Angewandte Chemie—and featured on the cover of the journal—the team describe the cobalt-catalyzed hydrogenation of alkenes, aldehydes, ketones, and imines under mild reaction conditions. The work thus opens the possibility of replacing the normally used noble metal catalysts with cobalt.
The most effective catalysts have been the noble metal elements such as platinum, palladium, rhodium, and ruthenium, which are a prohibitively expensive resource when required in large quantities. They could also become increasingly expensive as industrial applications increase worldwide. A push in sustainable chemistry thus has been to develop alternatives to the precious metal catalysts by using relatively inexpensive, earth-abundant metals.
The chemical complexities of the more common metals have made this research a challenge, but the Los Alamos paper holds out the possibility that the earth-abundant metal cobalt can serve in place of the noble metals.
Cobalt, like iron and other transition metals in the Periodic Table, is cheap and relatively abundant, but it has a propensity to undergo irreversible reactions rather than emerging unchanged from chemical reactions as is required of an effective catalyst. The discovery by the Los Alamos team was to capture the cobalt atom in a complex molecule in such a way that it can mimic the reactivity of precious metal catalysts, and do so in a wide range of circumstances.
The findings of the Los Alamos team suggest that cobalt complexes are rich with possibility for future catalyst development. Due to the high performance and low cost of the metal, the cobalt catalyst has potential applications in energy-related technologies such as the production of biofuels, and the reduction of carbon dioxide. It also has implications for organic chemistry, where hydrogenation is a commonly practiced catalytic reaction that produces important industrial chemical precursors.
The research was funded by the LANL Laboratory Directed Research and Development Early Career program.
Zhang, G., Scott, B. L. and Hanson, S. K. (2012) Mild and Homogeneous Cobalt-Catalyzed Hydrogenation of C=C, C=O, and C=N Bonds. Angew. Chem. Int. Ed., 51: 11907. doi: 10.1002/anie.201208739