Carbon-carbon Bond Cleavage for a Lignin Refinery

Carbon-carbon bonds, ubiquitous in lignin, limit monomer yields from current depolymerization strategies, which mainly target C-O bonds. Selective cleavage of the inherently inert sigma-type C-C bonds without pre-functionalization remains challenging. Here we report the breaking of C-C bonds in lignin obtained upon initial disruption of labile C-O bonds, achieving monocyclic hydrocarbon yields up to an order of magnitude higher than previously reported. The use of a Pt (de)hydrogenation function leads to olefinic groups close to recalcitrant C-C bonds, which can undergo beta-scission over zeolitic Br & oslash;nsted acid sites. After confirming that this approach can selectively cleave common C-C linkages (5-5 ', beta-1 ', beta-5 ' and beta-beta ') in lignin skeletons, we demonstrate its utility in the valorization of various representative lignins. A techno-economic analysis shows the promise of our method for producing gasoline- and jet-range cycloalkanes and aromatics, while a life-cycle assessment confirms its potential for CO2-neutral fuel production.