American scientists at the University of Delaware – chemist Joel Rosenthal and doctoral student John DiMeglio – have developed what is claimed to be a low-cost way of converting carbon dioxide into a synthetic fuel for multiple uses including power cars.
The key is an apparently inexpensive catalyst that uses the electricity generated from solar energy to convert the CO2 to a liquid fuel.
Gold and silver represent the “gold standard” in the world of electro-catalysts for conversion of CO2 to carbon monoxide.
But Rosenthal and his research team have pioneered the development of a much cheaper alternative to these expensive and precious metals. They are using the element bismuth (Bi), a silvery “poor metal” with a pink hue that’s a key ingredient in Pepto-Bismol, a famous pink elixir for settling an upset stomach.
“This catalyst is a critically important linchpin,” Rosenthal said. “Using solar energy to drive the production of liquid fuels such as gasoline (petrol) 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.”
A gramme of bismuth is 50 to 100 times cheaper than a gramme of silver, and 2,000 times cheaper than a gramme of gold, according to Rosenthal.
Bismuth is more plentiful than gold and silver, is well distributed globally and can be readily obtained as a byproduct in the refining of lead, tin and copper. Elemental Bi may also occur naturally.
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 CO2, they make a whole slew,” he said.
“Our goal was to develop a catalyst that was extremely selective in producing carbon monoxide (CO) and to power the reaction using solar energy.
“Many of us hear the words carbon monoxide and immediately think poison.
“It’s true that you do not want to be in a closed room with carbon monoxide. 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 for the production of synthetic petroleum, gasoline and diesel.
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.
Rosenthal reckons that if CO2 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.
He credits a scientific article published during the US’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 US 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.
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