Selective lignin conversion via flow photocatalysis for vanillin and bioplasticizers production

Lignin valorization remains a roadblock in the development of green biorefineries. Currently, depolymerization strategies predominantly depend on energy- and resource-intensive thermochemical methods, while potential applications of the resulting bio-based products are often overlooked. Here, we show a scalable photocatalytic flow reactor for lignin deconstruction that operates at ambient conditions, along with a downstream process that yields commercially viable products at gram scale. An anthraquinone-based photocatalytic platform, when packed in a flow bed reactor, is demonstrated to selectively and nearly quantitatively cleave lignin's β-O-4 moieties, achieving a benchmark yield of 7.1 wt% for vanillin. The utilization of residual oligomers as plasticizers for biobased polylactic acid resulted in improved mechanical properties and shape memory effects, while maintaining its suitability for conventional 3D printing. This aldehyde-oriented platform represents a key advancement that complements existing ketone-oriented photocatalytic approaches targeting valuable chemicals from lignin conversion, and it ultimately contributes to the holistic utilization of lignin.