Making Methanol

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Science  04 May 2012:
Vol. 336, Issue 6081, pp. 520
DOI: 10.1126/science.336.6081.520-c

If chemistry worked like Tinkertoys, it would be rather straightforward to make methanol from methane: You'd simply pull off a hydrogen atom and stick on an OH group. Alas, it's not that simple, and most scalable implementations of this reaction tend toward overoxidation; the primary industrial route circuitously oxidizes the carbon to CO before reducing it back down to the alcohol. Hammond et al. explored one means of taming the direct oxidation, so as to stop at the desired product. Specifically, they sought to optimize zeolite-catalyzed oxidation of methane by hydrogen peroxide. They first discovered that trace iron is essential to the catalytic activity and went on to map out a preliminary diiron-centered mechanism using a combination of spectroscopic probes and density functional theory simulations. Next, the authors observed that OH radicals underlie overoxidation processes and that the introduction of copper ions stems this activity. A combination of iron and copper additives to the zeolites offered >90% methanol selectivity at ∼10% methane conversion. Although hydrogen peroxide is currently an expensive oxidant to apply to commodity-scale methanol synthesis, the selectivity principles uncovered in the study may enhance selective hydrocarbon oxidation processes more broadly.

Angew. Chem. Int. Ed. 51, 10.1002/anie.201108706 (2012).

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