CO2 Plus Energy Equals Organic Chemicals
Liquid Light, a New Jersey startup company, claims to be able to turn carbon dioxide into fuels and industrial chemicals. The innovative technology behind the process is simple: Take CO2 and mix it in a water-filled chamber with an electrode and a catalyst. The ensuing chemical reaction converts CO2 into a new organic molecule, methanol, which can be used as a fuel, an industrial solvent or a starting material for the manufacture of other chemicals. What is most promising about this technology is that it maybe way to use Carbon Dioxide that might be otherwise emitted to the air or be sequestered in the ground or ocean.
Liquid Light's founders include Bocarsly and his former graduate student Emily Cole. Cole helped revive efforts in Bocarsly's lab to study the conversion of CO2 into usable fuels, which led to the launch of Liquid Light and an ongoing collaboration that Bocarsly said has been extremely positive for his research team at the University.
Back in the 1990s, a former Ph.D. student of Bocarsly's named Chao Lin conducted some of the earliest experiments on turning CO2 into methanol. He used palladium metal as the electrode and pyridinium, an inexpensive ring-shaped molecule, as the catalyst. By plugging the electrode into an electrical outlet, he could drive an electrochemical reaction that converted CO2 into methanol.
Further work languished until 2005 when Cole told Bocarsly she wanted to work on a clean-energy project. She took up the challenge of reproducing Lin's results, but this time using sunlight instead of electricity to drive the reaction.
In Cole's setup, photons hit a gallium phosphide semiconductor and excite its electrons to travel to the semiconductor's surface and into the surrounding water. The catalyst then shuttles the electrons to the CO2. Those electrons attract hydrogen from the surrounding water to turn CO2 (one carbon and two oxygens) into methanol (one carbon, one oxygen and four hydrogens) with the release of oxygen.
Bocarsly likes to call the process "reverse combustion" because it is like running a burning reaction backwards. Instead of burning fuel and oxygen to produce CO2, the CO2 converts back into fuel and oxygen.
The Princeton scientists did some additional studies, and made a surprising discovery: They could turn CO2, which contains only one carbon, into a compound with a carbon-carbon bond, which vastly increases the possibilities for creating commercial applications. This was radical because although the reaction is certainly possible, it is highly unlikely to happen because of so many other competing reactions are occurring.
"Everyone who electrochemically reduces CO2 today makes compounds with only one carbon," said Bocarsly. "Nobody makes things with carbon-carbon bonds." He paused. "But we can."
Liquid Light scientists can now make more than 20 different products from CO2. Examples include butanol and Isopropanol.
The Princeton team also is studying the factors that determine which products can be made from CO2. The researchers have found that very subtle changes in the electrode surface can lead to the production of different chemicals. The team published its findings on how the reaction is affected by catalyst concentration, temperature and pressure in the journal ChemSusChem last year.
Converting carbon dioxide into useful organic chemical base chemicals is similar in concept to what a plant does in photosynthesis but uses an alternate process. This is quite a promising subject but will require time and money to make into a viable commercial process.
For further information see Liquid Light or Princeton Lab.
Lab image by Denise Applewhite via University of Princeton.