Scientists at the US Department of Energy's Argonne National Laboratory have developed a new catalyst for converting carbon dioxide directly into the liquid fuel methanol. With its unique structure, this new catalyst is much more energy efficient than existing catalysts for converting carbon dioxide into methanol.

As recently reported in a paper in the Journal of the American Chemical Society, the catalyst comprises small clusters of four copper atoms, known as copper tetramers, supported on a thin film of aluminum oxide. The structure of the copper tetramer is such that most of its binding sites are open, allowing it to bind strongly with carbon dioxide and thus efficiently catalyze its conversion to methanol.

"With global warming becoming a bigger burden, it's pressing that we keep trying to turn carbon dioxide emissions back into something useful."Stefan Vajda, senior chemist at Argonne National Laboratory

The current industrial process for reducing carbon dioxide to methanol uses a catalyst of copper, zinc oxide and aluminum oxide. A number of its binding sites are occupied merely in holding the compound together, which limits how many sites can bind with carbon dioxide.

"With our catalyst, there is no inside," said Stefan Vajda, senior chemist at Argonne and co-author of the paper. "All four copper atoms are participating because with only a few of them in the cluster, they are all exposed and able to bind."

The current catalytic method needs to employ high-pressure conditions to enhance the strength of the bonds with carbon dioxide molecules. But compressing gas into a high-pressure mixture takes a lot of energy. With its enhanced binding, the new catalyst requires lower pressure and less energy to produce the same amount of methanol.

Carbon dioxide emissions are the prime cause of global warming and, according to the authors, it's important to identify optimal ways to deal with them. "We're interested in finding new catalytic reactions that will be more efficient than the current catalysts, especially in terms of saving energy," said Larry Curtiss, an Argonne Distinguished Fellow who co-authored the paper.

There is still a long way to go before this new catalyst can be used by industry. Potential obstacles include instability and figuring out how to manufacture mass quantities. There's a chance that copper tetramers may decompose when put to use in an industrial setting, so ensuring long-term durability is a critical step for future research, Curtiss said. And while the scientists needed only nanograms of the material for this study, that number would have to be multiplied dramatically for industrial purposes.

Meanwhile, the researchers are interested in searching for other catalysts that might outperform the copper tetramer. But the scientists won't have to run thousands of different experiments, said Peter Zapol, an Argonne physicist and co-author of the paper. Instead, they will use advanced calculations to make predictions, and then test the catalysts that seem most promising.

"We haven't yet found a catalyst better than the copper tetramer, but we hope to," Vajda said. "With global warming becoming a bigger burden, it's pressing that we keep trying to turn carbon dioxide emissions back into something useful."

This story is adapted from material from Argonne National Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.