Lignin R&D and Innovations

Breakthrough in Converting Lignin into Bio-Aromatics

Mark Crocker and colleagues from University of Kentucky (US) have reported a breakthrough in the heterogeneously catalysed oxidative depolymerisation of lignin, using gold nanoparticles supported on a lithium–aluminium layered double hydroxide.

By targeting the abundant β-O-4 linkage within lignin, the group obtained low molecular weight aromatic monomers such as vanillin, vanillic acid and syringaldehyde. These monomers are typically used in the food and fragrance industry, but can also serve as pharma precursors, and have market values of $4,000–14,000 per tonne.

Lignin oxidation usually produces very low yields however, Crocker’s system had monomer yields reaching 40%.

One criticism of this new catalyst is that it is not industry friendly because it uses a precious metal. Crocker’s group is looking into significantly reducing the amount of gold required by alloying the gold with other less expensive metals. However, as Rinaldi states, ‘The current results definitely open up new avenues for the valorisation of lignin.’

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