May 04, 2016

SIU chemist’s research validated by overseas lab

by Tim Crosby

CARBONDALE, Ill. – Science moves forward in increments, one hard-earned fact building on another, each being verified time and again as progress occurs. 

For a researcher at Southern Illinois University Carbondale, that process was recently validated in a big way when a chemistry laboratory overseas validated his theoretical predictions, proving the vast amounts of carbon dioxide created by fossil fuels can be used to create an important chemical feed stock, or to store energy, adding value and reducing greenhouse gases in the process. 

Qingfeng Ge, professor of chemistry and biochemistry at SIU, conducted theoretical work starting some 10 years ago as an aspect of the “FutureGen” concept, which envisioned a futuristic power plant that captured and sequestered the CO2 it created during electrical generation. Ge’s concept looked at the sequestered CO2 as a potential resource and investigated whether it could be recycled in a way that would convert it to an organic state, where it could be used as a chemical feed stock to make many types of synthetic materials, or as an energy source. 

He eventually found a catalyst for efficiently using hydrogen to turn CO2 into methanol, which is a key chemical building block from which thousands of synthetic materials are produced and can also be used for energy. When used in cooperation with a sustainable energy source, such as wind or solar energy, the catalytic cycle not only leaves a tiny carbon footprint but also recycles the CO2 created by other fossil fuels into a useful material, rather than sequestering it or releasing it into the atmosphere. 

Just weeks ago, an applied chemistry group working in a laboratory in Zurich built a successful approach based on the Ge’s published work on converting CO2 to methanol. The work, by the ETH Group, showed that it is possible to convert CO2 to methanol on an industrial scale based on Ge’s prediction. 

Chemical & Engineering News, a weekly news magazine published by the American Chemical Society, highlighted the work in the March 28 issue. 

Ge said he was thrilled by the development. 

“I’m really excited, because computations are really just predictions,” Ge said, adding he didn’t know the Zurich group had begun work on their experiments using his theories. “And that made it very rewarding, that the work was independently confirmed. They saw our work and they implemented it themselves. From a pure theoretical chemist point of view, you can’t be more satisfied than that.” 

Instead of using CO2, chemical companies typically make methanol from syngas, which comes from processing fossil fuels such as coal or petroleum. Syngas is a mixture of carbon monoxide and hydrogen. Researchers have known that finding a way to directly hydrogenate CO2, rather than using syngas, would lead to a more efficient and sustainable way to create methanol. What was missing, however, was a catalyst – a substance that chemically facilitates a reaction without itself being affected – that was scalable in a practical way. 

Ge’s work identified a catalyst that would work: indium oxide. When placed in chemical reactor with CO2 and hydrogen, the end result is methanol. 

“A catalyst can speed up the process or make it a selective process, and the catalyst based on indium oxide made both happen,” Ge said. 

In chemical terms, the hydrogen, which would be produced by a sustainable energy source, would work to “reduce” the catalyst, extracting the oxygen atom from the indium oxide surface and forming water molecules, leaving an “anchoring site” or hole where it had once been. Next, the anchoring site, in effect, “grabs” the CO2 and in the process allows hydrogen to attach to the carbon atom, as well. 

As the cycle continues it eventually forms methanol. Subsequently, one of the oxygen atoms in the original CO2 molecule comes off and fills the hole, “healing” its surface and making it ready to repeat the cycle again, Ge explained. 

The same result could be achieved by heating the catalyst, but doing so not only uses a great amount of energy but also is hard to control. 

“We thought carbon monoxide would be even more efficient than hydrogen as a reducing agent at creating the oxygen vacancy,” Ge said. “And the ETH group used a small amount of carbon monoxide co-feeding with CO2 and hydrogen and made it work. They proved that the oxygen vacancy is the key part for the reaction to take place with nearly 100 percent methanol selectivity.” 

The work in Zurich also showed such a process could be “scaled up” to industrial capacity, an exciting prospect on many fronts, Ge said. 

“Converting CO2 directly to methanol and other value-added chemicals would avoid the use of petroleum and provide a means to utilize captured CO2 and reduce net emission of this greenhouse gas,” Ge explained in a statement. “There have been tremendous efforts aimed at developing catalysts and processes that are capable of achieving this goal.”