Chemist Joel Rosenthal University of Delaware’s (UD) Department of Chemistry and Biochemistry, and doctoral student John DiMeglio have developed an inexpensive catalyst that uses the electricity generated from solar energy to convert carbon dioxide to the commodity precursor chemical carbon monoxide.
A little background: in fuel combustion the carbon and hydrogen components of the fuel molecule react with oxygen. The fuel molecule comes apart and the atoms reform into primarily water, carbon dioxide and carbon monoxide. Both the water molecule and carbon dioxide are essentially complete energy releasing reactions with no further easy gains. But the carbon monoxide is both and opportunity and problem.
Many of us think about ‘carbon monoxide’ and react thinking ‘poisonous gas’. That’s entirely true in the wrong circumstances. In a modern emission controlled engine the carbon monoxide is moved through the catalytic converter where more oxygen is added reacting the gas on to non-poisonous carbon dioxide. This process produces a lot of wasted heat.
Rosenthal reminds us, “But carbon monoxide is very valuable as a commodity chemical because it’s extremely energy rich and has many uses.” Reforming CO2 back to CO can be a very advantageous idea. Carbon monoxide is used industrially in the water-gas shift reaction to make hydrogen gas. It also is a prime feedstock for the Fischer-Tropsch process, which allows for the production of synthetic petroleum, gasoline and diesel.
It’s a route to CO2 recycling without relying on biological steps.
Commercial production of synthetic petroleum is under way or in development in a number of countries, including Australia and New Zealand, China and Japan, South Africa and Qatar.
Today gold and silver are the “gold standards” in the world of electrocatalysts for conversion of carbon dioxide to carbon monoxide.
Rosenthal and his research team have a breakthrough by pioneered the development of a much cheaper alternative to the pricey, precious metals. It’s bismuth, the silvery metal with a pink hue that’s a key ingredient in Pepto-Bismol, the famous pink elixir for settling an upset stomach.
Rosenthal notes an ounce of bismuth is 50 to 100 times cheaper than an ounce of silver, and 2,000 times cheaper than an ounce of gold. Bismuth is more plentiful than gold and silver; it is well distributed globally and is a byproduct in the refining of lead, tin and copper.
The breakthrough gets better. Rosenthal explains, “Most catalysts do not selectively make one compound when combined with carbon dioxide – they make a whole slew. Our goal was to develop a catalyst that was extremely selective in producing carbon monoxide and to power the reaction using solar energy.”
The team’s research has been published in the June 19 issue of the Journal of the American Chemical Society. UD has already applied to patent the catalyst.
The breakthrough may not be big news, but it’s important.
Rosenthal says that if carbon dioxide emissions become taxed in the future due to continuing concerns about global warming, his solar-driven catalyst for making synthetic fuel will compete even better economically with fossil fuels.
“This catalyst is a critically important linchpin,” Rosenthal says.
“Using solar energy to drive the production of liquid fuels such as gasoline from CO2 is one of the holy grails in renewable energy research. In order to do this on a practical scale, inexpensive catalysts that can convert carbon dioxide to energy-rich compounds are needed. Our discovery is important in this regard, and demonstrates that development of new catalysts and materials can solve this problem. Chemists have a big role to play in this area.”
Rosenthal credits a scientific article published during America’s first energy crisis in the 1970s for piquing his interest in bismuth. At that time, many researchers were examining the conversion of carbon dioxide to carbon monoxide using electricity and metal electrodes. The research went bust in the early 1980s when federal funding dried up. Rosenthal picked up the trail and blazed a new one.
“With this advance, there are at least a dozen things we need to follow up on,” Rosenthal notes. “One successful study usually leads to more questions and possibilities, not final answers.” Rosenthal’s lab will be operating at full tilt this summer, exploring some of those questions.
The research team of seven will have a temporary shot of extra help. Through the American Chemical Society’s Project SEED summer research program, budding scientists from nearby Newark High School will join Rosenthal’s team for further study of this bismuth-based catalyst.
The university team likely has good reason to think from a solar driven perspective. Commercial interests will act from a firm economic basis. Should the numbers work at this stage, no one will be waiting around for solar drives.
Rosenthal has an intriguing strategy in the reduction of CO2 to CO, generating an energy-rich commodity chemical that can be directly coupled to liquid fuel production. How a complete process might compare to an algae farm at a power plant is an interesting question.