U-M chemists have developed a new method which uses carbon dioxide to create metal oxalates, the precursors needed to make cement. With recent work proving the concept, the team is now taking aim at scaling the part of the process which produces the solid product.
"This research shows how we can take carbon dioxide, which everyone knows is a waste product that is of little-to-zero value, and upcycle it into something that's valuable," said Charles McCrory, associate professor of chemistry and macromolecular science and engineering. "We're not just taking carbon dioxide and burying it; we're taking it from different point sources and repurposing it for something useful."
Outlined in their recent publication in the journal Advanced Materials, the method explores the use of simple salts called metal oxalates as a cement precursor. After exploring possible catalysts to drive the conversion of carbon dioxide into oxalate the team landed on lead. While a promising option, lead presents unique environmental and human hazards when used in the quantity required.
To remedy these hazards the team developed a new polymer-based method which controls the environment immediately surrounding the lead catalysts, reducing the amount needed to ppb levels. By controlling the microenvironment surrounding the catalysts sites the team can tune the catalysts activity, vastly reducing the amount of lead needed while promoting the conversion of carbon dioxide to oxalate.
"In this work, we have an example of a trace lead impurity actually being a catalyst. I believe there are many more such examples in practice catalysis, and also that this is an underexplored opportunity for catalyst discovery," said Anastassia Alexandrova.
Amongst others, one main benefit of the process is that the carbon dioxide captured is converted into metal oxalate solids, meaning it will not be released into the atmosphere as carbon dioxide again under normal conditions.
"It's a true capture process because you're making a solid from it," concluded McCrory. "But it's also a useful capture process because you're making a useful and valuable material that has downstream applications."