An international team of researchers led by Switzerland’s École Polytechnique Fédérale de Lausanne, EPFL, has developed a method to convert plant-based lignin into valuable precursors for biofuels, plastics and other products.

The process, which can be scaled to industrial levels, is notable since lignin is difficult to break down and usually is discarded during biofuel processing.

Lignin extracts with (L) and without (R) formaldehyde. Source: Alain Herzog and J. Luterbacher/EPFLLignin extracts with (L) and without (R) formaldehyde. Source: Alain Herzog and J. Luterbacher/EPFLLignin, which makes up nearly a third of all plant biomass, is a complex biopolymer that fills the hard wall that surrounds each plant cell. Most biomass comes in the form of non-edible plants like trees, grass, and algae, which contain sugars that can be fermented to produce fuel.

Lignin is the substance that generally gives plants and trees their rigidity. It also has great potential as a renewable fuel source in that its molecular structures gives it an energy density 30% greater than that of the sugars traditionally processed into biofuel.

But, because it is unstable and difficult to process, its value as a bio-based precursor has yet to be fully realized.

Now, EPFL researchers say they may have found the key to unlocking lignin’s value. They’ve discovered that they can break lignin apart by adding the common chemical formaldehyde to the process.

Formaldehyde stabilizes lignin and prevents it from degrading, leading to high yields of building blocks that can be used to make substitutes for petrochemicals. In tests, researchers found that yields from the formaldehyde-treated lignin were three to seven times higher than those obtained from lignin without formaldehyde.

Formaldehyde also has another process advantage in that it’s already one of the most widely used chemicals in industry, and is simple and cheap to produce.

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