New catalyst developed to produce isobutene from bio-ethanol

The largest application for biomass is to burn it directly or to ferment it to produce ethanol. Converting biomass into other chemicals is often costly or inefficient, due to the many production steps needed.

However a new catalyst developed by researchers at the Department of Energy’s Pacific Northwest National Laboratory (PNNL) and at Washington State University (WSU) can turn bio-ethanol into isobutene in just one production step. Isobutene is an industrially important chemical mostly used for rubber production, as a solvent and as fuel additives.

Biobased economy

Catalysts such as the one presented in the Journal of the American Chemical Society are highly sought after, because they are invaluable in the transition from a petroleum based economy to a more sustainable biobased economy.

Accidental discovery

The discovery of the workings of the nanosized catalyst was more or less accidental. The mixed oxide that consists of a blend of two known catalysts, zinc oxide and zirconium oxide, was actually developed to produce hydrogen fuel from ethanol. But to the all but unpleasant surprise of the researchers they not only saw hydrogen in the resulting mix, but also quite a bit of isobutene.

Fine-tuning the mix

Put before a bit of a mystery, the research team set out to find the perfect composition of the catalyst. Eventually they found it at a 1:10 ration of zinc to zirconium, which consistently produces an 83 per cent yield with improved catalyst life.

Versatile and cheaper

A by-product of biomass fermentation is water. Bio-ethanol has to be purified to get rid of the water before it can be used. The new catalyst however requires the presence of water, allowing the use of cheaper unpurified bioethanol.

This combined with the versatility of isobutene as a chemical can greatly expand the applications for sustainably produced bio-ethanol, perhaps decreasing society’s dependence on petroleum.

© Jorn van Dooren |

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