Energy-Efficient Process Devised to Convert CO2 to Methanol

Frédéric-Georges Fontaine (Université Laval)

Chemistry researchers at Université Laval in Québec City, Canada and Université de Toulouse in France developed a new process that converts carbon dioxide into the alternative fuel methanol in a single, more efficient step. The team led by Laval professor Frédéric-Georges Fontaine published its findings online earlier this month in the Journal of the American Chemical Society (paid subscription required).

According to the U.S. Department of Energy (DoE), methanol — also known as wood alcohol — has the same physical and chemical fuel properties as ethanol and is listed as an alternative fuel under the Energy Policy Act of 1992. Methanol can be produced from a variety of carbon-based feedstocks, including coal and natural gas.

Up to now, production of methanol required a multi-step process, first generating a synthesis gas, then feeding the synthesis gas into a reactor, where a catalyst produces methanol and water vapor. Partially due to the complexity of its production, methanol use has dropped significantly since the 1990s, although DoE’s National Renewable Energy Laboratory is researching methanol as a fuel cell feedstock for fuel cell vehicles.

Converting carbon dioxide to methanol, say the authors, requires a catalyst, which led to a combination of two types of chemicals. The first type is a borane, a carbon-hydrogen-boron compound. The second part of the catalyst is phosphine, a compound made of phosphorus, carbon, and hydrogen. Fontaine notes that unlike other catalysts used in the conversion of carbon dioxide, the catalyst devised by his team uses no metals, which reduces the cost and toxic hazards in the process.

Into the mix, Fontaine and colleagues introduced hydroborane, a boron-hydrogen compound, as the hydrogen and chemical energy source. The team’s lab results showed the ensuing reaction is twice as effective in generating methanol as the best known catalysts. And the process does not damage the catalyst, which can be reactivated by adding more reagents.

In addition, report the authors, the process produces very little waste, with yields as high as 99 percent. Those efficiencies, however, are offset by a high cost from the intense energy required to synthesize hydroborane, which makes it more expensive than methanol. Fontaine says the team is exploring other sources of hydrogen and working on ways to optimize the process to make the process more cost-competitive.

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