Pulling carbon dioxide out of the atmosphere and converting it into fuel or other useful chemicals is the aim of carbon capture and recycling technologies. Methanol is one possible product of such technologies, and it is attractive because it can be blended with transportation fuels, used in direct-methanol fuel cells or exploited as a hydrogen storage medium. As such, a ‘methanol economy’ has been proposed where methanol is used as an energy carrier to replace fossil fuels. Now, George Olah, G. K. Surya Prakash and colleagues at the University of Southern California, have developed a homogeneous catalyst system that allows carbon dioxide captured from air to be converted directly into methanol without intermediate steps.
Using a ruthenium-based catalyst and a polyamine, the researchers showed that a mixture of carbon dioxide and hydrogen could be efficiently converted into methanol in a one-pot process. Carbon dioxide is captured by the polyamine before being hydrogenated by the ruthenium catalyst. Importantly, the catalytic system could be used to generate methanol from synthetic air containing as little as 400 ppm of carbon dioxide, the typical concentration in the atmosphere. The researchers found that 79% of the carbon dioxide could be converted into methanol. The reaction proceeds at relatively mild temperatures (125–165 °C) and the catalyst can be recycled up to five times with little loss in activity.
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Gallagher, J. Catalysis: Fuel from air. Nat Energy 1, 16008 (2016). https://doi.org/10.1038/nenergy.2016.8