The dominating catalytic approach to aromatic hydrocarbons
from
renewables, deoxygenation of phenol-rich depolymerized lignin bio-oils,
is hard to achieve: hydrodeoxygenation (HDO) of phenols typically
leads to the loss of aromaticity and to non-negligible fractions of
cyclohexanones and cyclohexanols. Here, we report a catalyst, niobia-supported
iridium nanoparticles (Ir@Nb
2
O
5
), which combines
full conversion in the HDO of lignin-derived phenols with appreciable
and tunable selectivity for aromatics (25–95%) under mild conditions
(200–300 °C, 2.5–10 bar of H
2
). A simple
approach to the removal of Brønsted-acidic sites via Hünig’s
base prevents coking and allows reaction conditions (
T
> 225 °C, 2.5 bar of H
2
), promoting high yields
of aromatic hydrocarbons.
Here we report the first heterogeneous iridium-based catalyst (Ir@Nb2O5) able to combine full conversion in hydrodeoxygenation (HDO) of lignin-derived phenols to hydrocarbons with appreciable selectivity for aromatics. With temperature and pressure optimization, and coking inhibition by selective removal of acid sites, the aromatic yields reach 69% under mild conditions.
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