A University of Toronto research team led by Nobel laureate John Polanyi has reported success in making catalysis more selective.

The team’s results, reported in Nature Communications, indicate that the position of a molecule on the catalyst’s surface is a significant factor in determining the rate at which bonds break.

Science Research Building. Credit: University of TorontoScience Research Building. Credit: University of TorontoThis work reportedly builds on Polanyi’s Nobel winning research, which studied molecular motions in chemical reactions.

The team studied the breaking of carbon-to-iodine bonds in iodobenzene, an organic compound, adsorbed to the catalyst, metallic copper. They initiated a chemical reaction by delivering an electron through a tunneling electron microscope to a molecule of iodobenzene. The targeted bonds broke more quickly, by a factor of 100, when the bonds aligned along rows of copper atoms, as opposed to aligning crosswise.

“The copper atoms along the rows were slightly closer together, by about the diameter of a single atom, than the atoms across the rows,” says Ph.D. student Kelvin Anggara. “This closer spacing promoted the breaking of bonds lying along the rows.” The research results aligned with a mathematical model the team had developed over the past few years.

The research may be important as science comes to rely more heavily on catalysis. Polanyi says that chemists know little about a catalyst’s mode of action. The shift toward "green" chemistry increases the need to understand catalysts and catalysis better, since use of catalysts reduces chemical process waste.

“The challenge for the future will be to fabricate metal catalysts embodying atomic patterns that speed chemical reactions along pathways that lead to desired products,” says Polanyi. “We’re now a bit closer to that, since we begin to understand what patterns of atoms make the best catalysts.”

To contact the author of this article, email engineering360editors@globalspec.com