Researchers at Iramis CEA (Laboratory of Molecular Chemistry and Catalysis for Energy (LCMCE) managed to produce methanol from formic acid with a yield of 50%, well above the achieved so far efficiency level (2%).
To obtain such a result, researchers developed a model based on ruthenium metal catalyst, ten times cheaper than iridium, the element used to date for the formation of methanol.
Today 85% of world energy demand is provided by fossil fuels. The production of new fuels based on renewable energy and low-carbon forms with a view to independence from fossil fuels.
Compound used both in the fuel cell integrated in combustion engines converter, methanol could provide the key to producing fuel with high energy density, from renewable resources. It can in fact be formed from the six electron reduction of a renewable carbon material, the CO2. However the existing catalysts for the direct conversion (electrolysis) of CO2 in methanol are not effective and pose problems associated with the use of high pressures.
The two-electron reduction of CO2 to formic acid is, in turn, efficient and well controlled. An interesting to convert CO2 to methanol alternative would be to use the formic acid as a relay, being provided then effectively capable of converting the latter to methanol.
In 2013, the first catalysts for the conversion of methanol into formic acid emerge, with the work of the group K. Goldberg at the University of Washington. However, this is based on the advanced use of a particularly expensive metal, iridium, and methanol is obtained with a maximum yield of 2%. For an effective overall approach in the use of CO2 as an energy carrier, improved efficiency is needed.
Today Iramis CEA teams come to develop a effective ruthenium catalysts to produce methanol via formic acid with yield up to 50%. Moreover, the use of ruthenium instead of iridium has a certain economic advantage, this metal being more than ten times less expensive than iridium. The mechanism of the reaction has been studied by a dual experimental and theoretical approach, which helped highlight the reaction intermediates and the catalytic species involved in the formation of methanol. It has thus been shown that the active catalyst species is a complex hydride of ruthenium can effectively redistribute the C-H bond of the formic acid.
This reaction makes it possible to form methanol and two molecules of CO2 from three molecules of formic acid. The total carbon footprint is so favorable since three molecules of CO2 are needed to prepare three formic acid molecules.
To complement this approach, the researchers plan to combine these two reactions to assess the overall energy efficiency of the new strategy for the synthesis of methanol from CO2.