Exotic metal may help convert carbon dioxide to liquid fuels

An alarming trend first documented atop Mauna Loa could be reversed by way of an exotic metal, scientists report.

A researcher at the University of Deleware, citing a kind of “modern alchemy,” has found that the metal bismuth has an unusual property that can help convert carbon dioxide, a greenhouse gas, into liquid fuels and industrial chemicals.

The findings were reported recently in the journal ACS Catalysis, published by the American Chemical Society. The team led by professor Joel Rosenthal also has filed a patent on the work.

Bismuth, a shiny silver metal with streaks of pink and gold, is currently used to make products ranging from shotgun pellets to cosmetics and antacids, including Pepto-­Bismol.

Rosenthal found that when an electrical current is applied to a bismuth film in a bath of salty liquids containing imidazolium and amidinium ions, he and his team could “tune” the chemical reaction to convert carbon dioxide to either a liquid fuel such as gasoline, or to formic acid — a valuable chemical with many industrial uses, from preserving human food and livestock feed, to manufacturing rubber and leather, artificial flavorings and perfumes.

“We’re working to push the boundaries of this idea,” Rosenthal said in a release. “Our new findings are important from a technological standpoint—we think this platform will allow renewable energy sources such as solar and wind to drive the direct production of liquid fuels. But more importantly, we believe this concept of ‘catalytic plasticity’ signals a potential paradigm shift, a new way to think about renewable energy conversion, fuel production and catalysis, in general.”

Rosenthal and his team previously showed that bismuth films can be used in conjunction with certain liquid salts as inexpensive catalysts for converting carbon dioxide and renewable energy to gaseous fuels such as carbon monoxide. In this study, they found they could use the same materials in the presence of different salts to convert carbon dioxide directly to liquid fuels.

“Thinking about how you can take something cheap and plentiful and convert it into something much more useful and valuable without having to dump a lot of extra energy into it has always captured my imagination,” he said. “There are philosophical parallels between catalysis and the goals of the ancient alchemists. Alchemy is a loaded word, but in some ways, what we are studying is like modern alchemy — efficiently transforming carbon dioxide to more valuable fuels and chemicals is akin to trying to convert lead to gold.”

What impact could Rosenthal’s technology have on atmospheric carbon dioxide levels?

“It’s hard to predict the direct impact on those levels,” he said. “This technology would allow us to make liquid fuels using renewable electricity from sunlight and wind. This, in turn, would decrease our need for conventional petroleum resources, resulting in fewer carbon dioxide emissions.”

In April, Earth’s atmosphere attained its highest sustained levels of carbon dioxide since humans have been monitoring it more than 60 years ago — exceeding 410 parts per million for the entire month — according to measurements made at Mauna Loa Observatory.