Study advances new path for better methanol manufacturing

Dialing up the power on electricity-driven chemical reactions doesn’t guarantee that they’ll be more efficient, suggests a new study, a finding that gets researchers closer to creating the ideal conditions for sustainable chemical manufacturing.

Scientists identified this limitation by converting carbon monoxide into methanol — a vital fuel source and industrial ingredient — showing that how well the reaction works depends not only on applied voltage, but also on how quickly a catalyst binds to carbon monoxide molecules.

By revealing how certain steps control the reaction’s speed, these findings could help scientists design better methods and processes for producing cleaner fuels and chemicals, said Zhihao Cui, lead author of the study and a postdoctoral student in chemistry at The Ohio State University.

“We really want to replace conventional chemical manufacturing with sustainable chemical manufacturing powered by renewable electricity,” said Cui. “But to achieve that goal, we first need to overcome the fundamental restraints that stand in the way.”

One such restriction includes the effort it takes to turn carbon monoxide into methanol, a tedious, time-intensive process. Yet this team’s results provide new insights into how to design catalysts and their surroundings more efficiently, paving the way for cleaner, more efficient chemical production.

The study was published Nov. 2 in Nature Chemistry.

The team achieved this result by attaching a metal-based catalyst to carbon nanotubes — tiny tubes of graphene that have unique electrical properties — and filling them with carbon monoxide. After driving different levels of electricity through each, the team saw that a cobalt-based catalyst could hold onto those molecules more strongly than other metal catalysts.

Through their experiments, researchers also found that both the chemical environment and the binding strength of the catalyst can affect the outcome of a chemical reaction.

“One breakthrough here is that we show that both the surrounding electrolytes and how fast the environment can reorganize to accommodate the molecule influences how quickly molecules adsorb,” said Cui. “But what determines how fast carbon monoxide absorbs onto the catalyst depends on how quickly the environment can reorganize to accommodate the molecule.”

This means that at lower voltages, the reaction may be limited by how quickly the electrons can transfer to drive the reaction. In contrast, at higher voltages, the race shifts to how quickly carbon monoxide attaches to the catalysts. Both scenarios can slow methanol production.

Further analysis suggests the work has deeper sustainability implications, as converting carbon monoxide into methanol means that the carbon dioxide it originates from can be turned into useful products rather than be released back into Earth’s atmosphere, said Anne Co, co-author of the study and a professor in chemistry and biochemistry at Ohio State.

“People have been looking for new ways to use electrolysis, but they hit a ceiling,” she said. “But by improving the steps behind the process, we can better use renewable sources to significantly reduce CO2 and CO emissions.”

As such, she said, using the team’s framework in tandem with carbon utilization technologies could boost industrial interest in sustainable energy and help reduce society’s reliance on fossil fuels.

Overall, their work serves as a powerful foundation for developing next-generation catalysts and electrochemical systems critical for the creation of fuels and other important chemicals, said Co.

Next, the team plans to explore whether these findings can also improve other chemical processes, test how well the system performs over longer periods of time, and assess how well their process holds up against conventional methanol production methods.

“There are many directions to explore from this research,” said Co. “But I hope to encourage future scientists to ask critical questions and think deeply of their findings.”

This work was supported by the U.S. National Science Foundation and Ohio State’s Department of Chemistry and Biochemistry. Alina Mary Varghese of Ohio State was also a co-author.