Washington: Scientists claim to have succeeded in overcoming a major obstacle to a promising technology that simultaneously reduces atmospheric carbon dioxide and produces fuel.
A team at the University of Illinois, led by Paul Kenis, in fact, claims to have produced a catalyst that improves artificial photosynthesis -- the process of converting carbon dioxide gas into useful carbon-based chemicals, most notably fuel or other compounds usually derived from petroleum.
In artificial photosynthesis, an electrochemical cell uses energy from solar collector or a wind turbine to convert CO2 to simple carbon fuels such as formic acid or methanol,
which are further refined to make ethanol and other fuels.
"The key advantage is that there is no competition with the food supply and it is a lot cheaper to transmit electricity than it is to ship biomass to a refinery," said Richard Masel, a team member and CEO of Dioxide Materials, a start-up company involved in the process.
However, one big hurdle has kept artificial photosynthesis from vaulting into the mainstream: The first step to making fuel, turning carbon dioxide into carbon monoxide, is too energy intensive. It requires so much electricity to drive this first reaction that more energy is used to produce the fuel than can be stored in the fuel.
The Illinois group used a novel approach involving anionic liquid to catalyse the reaction, greatly reducing the energy required to drive the process. The ionic liquids stabilize the intermediates in the reaction so that less electricity is needed to complete the conversion.
The researchers used an electrochemical cell as a flow reactor, separating the gaseous CO2 input and oxygen output from the liquid electrolyte catalyst with gas-diffusion
electrodes. The cell design allowed them to fine-tune the composition of the electrolyte stream to improve reactionm kinetics, including adding ionic liquids as a co-catalyst.
"It lowers the overpotential for CO2 reduction tremendously. Therefore, a much lower potential has to be applied. Applying a much lower potential corresponds to
consuming less energy to drive the process," said Kenis.
The findings have been published in the `Science` journal.
First Published: Friday, October 07, 2011, 17:53