Designing Catalysts for Sustainability

MacArthur Fellow is a chemist.

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By Marlene Cimons, National Science Foundation

Chemist Melanie Sanford uses metals in combination with different chemicals to create catalysts. These, in turn, cause important processes to move faster, under milder conditions, and with far less waste and undesirable byproducts.

“We use these metals to get reactions that would otherwise be hard to do, and we get them to go exactly in the way we want them to go,” she says.

Potentially, the impact of her research could be enormous. Among other things, she is working on a catalytic system that can turn carbon dioxide into methanol--a fuel for automobiles--as well as another that could prompt the faster production of pharmaceutical drugs, eliminating unnecessary steps, and resulting in a drug with fewer toxic side effects.   

“By cutting down the number of steps, you make the process greener along the way,” she says, of the impact on drug manufacturing. “Ultimately, it gets to market faster, with less environmental impact, generating less waste, and with a safer end product.”

The National Science Foundation-funded scientist, a recent winner of a prestigious $500,000 “no strings attached” MacArthur Fellowship, or “genius” grant, is a professor of chemistry at the University of Michigan, who also works as a research partner with the Center for Enabling New Technologies through Catalysis, based at the University of Washington. 

“Melanie thinks very creatively, and is willing to take risks,” says Karen Goldberg, who directs the center. “As our goal in the center is high risk, high reward science, she is terrific to have as a team member. She is always thinking about the next great idea, and her contributions have been among the most significant in the center.” 

The center, a National Science Foundation Center for Chemical Innovation, which receives $3 million annually from the NSF, is working on about a dozen research projects, including Sanford’s, with the goal of developing sustainable methods for producing chemicals and fuels.    

“It is well known that American petroleum resources are very limited, and there are serious national security issues related to our dependence on imports for energy and chemicals,” Goldberg says. “Moreover, increasing global consumption of fossil fuels is of great concern in the context of climate change.  New methods for the production of our chemicals and fuels will substantially reduce environmental impact by lowering the amount of energy used and the amount of waste produced.”

Sanford’s research converting carbon dioxide into methanol grew from her interest in the natural processes of plants, who, through photosynthesis, absorb CO2 to make food.

“Our catalysts are different from what nature does, but I was inspired that nature can take carbon dioxide and use its own catalysts to turn CO2 into something that is not a greenhouse gas, but can be used as a fuel for the plant,” Sanford says.

“We wanted to do something similar, but make methanol, a fuel that can be used in a car,” she adds. “Ideally, we capture CO2, convert it into a fuel, burn it as a fuel and capture it again. It would be a carbon neutral cycle.”

Her approach differs from earlier researchers, who, “in the past, would experiment with just one metal,” she says. “But that’s not how nature does it.  Nature uses lots of different enzymes and steps.”

She set out to mimic nature, designing a series of catalysts that each, individually, performs a step and then passes it on to the next catalyst, for another step, and so on, with methanol as the final product.  She uses the metal ruthenium for the first step, scandium for the second, and then a ruthenium variation for the third step--and it seems to work.

To be sure, the process is not close to commercial scale, “but we are looking at the best ways to design catalysts for that system,” she adds.

With pharmaceuticals and agro-chemicals, as well as other consumer products, such as plastic bottles, she is developing catalysts that will act upon un-reactive molecular bonds,  such as those composed of carbon and hydrogen. “We want to design catalysts that will take those bonds and turn them into something different,” she says.

“Suppose you have a pharmaceutical with some toxicity,” she continues. “It might be possible to completely change it by just switching a single bond. Traditionally, people had to go back ten, 20 or 30 steps of synthesis to introduce something new. Our chemistry allows you to take something close to the final product, and manipulate the bonds much more quickly, with much less waste, cost and manpower.  You can turn it into a new group and make a new derivative of a drug that reduces the toxicity. It really streamlines the drug delivery process.”

Sanford says the MacArthur award came “totally out of the blue,” and she isn’t sure yet how she’s going to use the money. However, she expects to direct part of it toward finding less expensive metals for her experiments, as ruthenium is both rare and quite expensive.  “We often are dependent on the willingness of the governments of other countries to share it with us,” she says.

Beyond her specific projects, “we really want to understand the fundamental aspects of how these catalysts work--not just whether they can make a drug, but structurally how they work,” she says. “Once you understand how they work, you can tailor them for other applications. We’re very focused on the structural details of these catalysts and how they operate on a molecular level. Once you understand this, it gives you the power to design all sorts of other new things that can spring from it.”

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