To break, or not to break: is selective depolymerization of lignin a Riemann hypothesis rather than a solution?

Abstract

Lignin—nature's most complex, frustratingly stubborn macromolecule—has long been the poster child for biomass valorization's unrealized potential. Despite decades of hand-wringing over selective depolymerization to produce aromatic monomers, progress remains embarrassingly slow. This perspective article tackles the elephant in the room: is chasing the Holy Grail of high selectivity really the best use of our time and resources? Or should we finally admit that lignin's complexity demands a more pragmatic approach? We argue for a radical shift in perspective, advocating for a “liquefy-first” strategy that ditches the impossible dream of perfect depolymerization in favor of producing a heterogeneous liquid feedstock. As such, this feedstock could be fed into existing industrial processes, bypassing the tedious obsession with monomer purity. Maybe it is time to re-evaluate what success looks like in lignin research and embrace solutions that could move us faster toward a carbon-neutral future—without chasing the unicorn of selective breaking down.