24th June 2013
A cheaper drive to 'cool' fuels
Researchers at the University of Delaware are developing an inexpensive catalyst to drive the production of synthetic fuel that could one day replace liquid fossil fuels.
University of Delaware chemist Joel Rosenthal is driven to succeed in the renewable energy arena. Working in his lab in UD's Department of Chemistry and Biochemistry, Rosenthal and doctoral student John DiMeglio have developed an inexpensive catalyst that uses electricity generated from solar energy to convert carbon dioxide, a major greenhouse gas, into synthetic fuels for powering cars, homes and businesses.
Gold and silver represent the "gold standard" in electrocatalysts for the conversion of carbon dioxide to carbon monoxide. But Rosenthal and his research team have pioneered the development of a much cheaper alternative to these pricey, precious metals. It's bismuth, a colourful metal that's a key ingredient in Pepto-Bismol, a well-known drug for settling an upset stomach.
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, Rosenthal says. 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.
Moreover, Rosenthal says his UD-patented catalyst offers other important advantages: selectivity and efficiency in converting carbon dioxide to fuel.
"Most catalysts do not selectively make one compound when combined with carbon dioxide — they make a whole slew," Rosenthal explains. "Our goal was to develop a catalyst that was extremely selective in producing carbon monoxide and to power the reaction using solar energy."
Many of us hear '"carbon monoxide" and think "poison."
"It's true that you do not want to be in a closed room with carbon monoxide," Rosenthal says. "But carbon monoxide is very valuable as a commodity chemical, because it's extremely energy rich and has many uses."
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 production of synthetic petroleum, gasoline and diesel. Commercial production of synthetic petroleum is underway or in development in a number of countries, including Australia and New Zealand, China and Japan, South Africa and Qatar. 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," he 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. Their latest research is published in the Journal of the American Chemical Society. This follows a similar breakthrough last week in which scientists at Université Laval developed a highly effective method for converting CO2 into methanol.