Method to Oxidise Renewable Chemicals from Biofuel Byproducts

A method of using oxygen to convert lignin into a source of renewable chemical feedstocks has been developed by chemists at the University of Wisconsin-Madison.

A method of using oxygen to convert lignin, a byproduct of biofuel production, into a form that could replace fossil fuels as a source of renewable chemical feedstocks has been developed by chemists at the University of Wisconsin-Madison (UW-Madison).

Lignin is associated with cellulose - plant matter which is often used to make paper and biofuels - and is a complex organic material found in trees and other plants.

However, according Shannon Stahl, a UW-Madison professor of chemistry and expert in catalysis and green chemistry, the complexity of lignin makes it difficult to convert into valuable products.

"Lignin is essentially a waste product of making biofuel, and it is usually just burned as a fuel or used as a low-cost additive in asphalt or concrete," explained Stahl.

"If we could take this waste lignin and increase its value, we could improve the economics for biomass derived fuels and provide a chemical feedstock that does not rely on fossil fuels," he continued.


According to Stahl chemists have previously taken lignin apart previously with oxidation, but it is a process which can be akin to smashing something with a sledgehammer, leaving shrapnel everywhere.

"You get some of what you want, but much of it ends up as unusable bits and pieces," he said.

The university explained that the focus of this work is to very selectively oxidise the lignin under very mild pressure and temperature with a catalyst that is specific for a single structure on the lignin molecule.

"It's like using a scalpel and tweezers, rather than a sledgehammer, and getting exactly what we want from the molecule, and nothing else. Theoretically, the only byproduct of the process is water," added the professor.

Final use?

According to Stahl the use of lignin as a source of chemical feedstocks is part of an emerging subfield of chemistry being built around biomass-derived chemicals.

However, the professor admitted that it's not yet possible to know how the new intermediates would be used to make final products.

"The way the chemical industry is built, you take what nature gives you and find ways to convert it into interesting and important products that people want to buy. Ultimately, methods of this type can be used to limit our reliance on non-renewable chemicals," commented Stahl.

"Rather than having tankers loaded with crude oil supplying the raw material for fuels, plastics and pharmaceuticals, we could start with renewable feedstocks," he concluded.

The research was carried out in collaboration with John Ralph, a professor of biochemistry associated with the Great Lakes Bioenergy Research Center on the UW campus.

The researchers have applied for a patent on the process, and patent rights have been assigned to the Wisconsin Alumni Research Foundation.

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