Abstract:
Global temperature has risen >1 °C since the preindustrial
era, resulting in well-documented adverse climate impacts including extreme
weather (floods, droughts, storms, and heat waves), a rise in sea level
accompanying melting polar and glacial ice, and disrupted crop growth.
These changes are closely correlated with anthropogenic greenhouse gas
emissions, predominantly arising from the combustion of nonrenewable
fossil fuels. Lignin derived from lignocellulose is the second most abundant
biopolymer on Earth, and a rich source of renewable aromatic hydrocarbons
to replace those currently obtained from fossil resources. Lignin
depolymerization by cleavage of C−O and C−C linkages in the biopolymer
can be achieved by direct pyrolysis or catalytic transformations, involving
oxidation, hydrolysis, or hydrogenolysis reactions. Hydrogenolysis, in which
H2 gas (or in-situ generated reactive H species) is supplied to lignin under
relatively mild conditions, has attracted significant attention. This Perspective summarizes recent progress in the development of
heterogeneous catalysts for the cleavage of C−O linkages in lignin-derived aromatic ethers by hydrogenolysis: it encompasses
strategies using H2, hydrogen transfer, and photocatalysis for aromatic monomers production, and the determination of structure−
activity relationships and underlying reaction mechanisms.
