Georgia Tech researchers have developed a new method for converting lignin, a complex organic polymer found in plants, into valuable chemicals. This innovation uses mechanocatalysis, which involves physical forces such as vibration or rotation in a ball mill to drive chemical reactions without solvents, heat, or high pressure.
Carsten Sievers from Georgia Tech’s School of Chemical and Biomolecular Engineering highlighted the importance of depolymerization in breaking down lignin into small molecules. He stated that many traditional depolymerization processes require solvents, complicating the separation of products and leading to waste. "One way to reduce the need for these separation steps is to perform lignin depolymerization in a ball mill where collision with steel balls create environments that enable solid-state reactions without the need for solvents or liquid phases," Sievers explained.
The research team employed palladium catalysts to enhance the breakdown of lignin's bonds. Erin Phillips, a graduate student co-advised by Professors Sievers and Marta Hatzell, emphasized palladium's ability to store hydrogen, improving reaction efficiency. Their collaboration with Eli Stavitski at Brookhaven National Laboratory utilized synchrotron x-rays to confirm that this hydrogen binding prevents its escape during milling.
Phillips noted the significant increase in efficiency using palladium catalysts: "This remarkable increase in efficiency means that the process can produce more phenol and other valuable chemicals in a shorter amount of time, making it a promising approach for large-scale biomass conversion."
Sievers' group had previously demonstrated hydrogenolysis with nickel catalysts but sought improvement due to its lengthy reaction time.