Room Temperature is Warm Enough: Power from Formic Acid

A team at the Leibniz Institute of Catalysis in Rostock, Germany, has succeeded in the controlled extraction of hydrogen from formic acid - without the need for high-temperature reforming usually involved in other hydrogen-generation systems. This hydrogen can be introduced directly into fuel cells.

The process generates on-demand hydrogen from formic acid (HCO^sub 2^H) in the presence of an amine (e.g., /V,W-dimethylhexylamine) and a suitable catalyst (e.g., ruthenium phosphine complex [RuCl^sub 2^(PPH^sub 2^)^sub 2^]). Formic acid is converted selectively into carbon dioxide and hydrogen at room temperature. A simple activated charcoal filter is enough to purify the hydrogen gas for use in a fuel cell.

While hydrogen-powered fuel cells are the cleanest source of energy, transportation and storage of hydrogen are not practical, as the gas cannot be pumped into a tank as easily as liquid fuels. Hydrogen-producing materials that supply the fuel cell on-demand (Le., methane, methanol, and renewable resources such as biomass and its fermentation products) have their own serious disadvantage, in that their conversion only works at temperatures above 200°C, which consumes a significant portion of the energy produced.

The use of formic acid for hydrogen storage combines the advantages of established hydrogen/oxygen fuel-cell technology with those of liquid fuels. Formic acid is nontoxic and easy to store. Because it can be generated catalytically from CO2 and biomass-derived hydrogen, in principle, the cycle is CO2-neutral.

While formic acid may not replace gasoline as a transportation fuel in the near future, initial applications requiring smaller amounts of energy are more probable. "For the use of fuel cells in portable electrical devices, this nascent formic acid technology opens up new possibilities in the short term," says Mathias Beller, professor at the Institute.

Copyright American Institute of Chemical Engineers Jun 2008
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