Utilization of naturally occurring
limonene from renewable biomass
as a key starting material for the synthesis of valuable chemicals
is a promising avenue to reduce both the dependence on nonrenewable
fossil fuels and global CO2 emission. Herein, we report
a highly active tremella-like ZnCo2O4 catalyst
for the selective oxidation of limonene with molecular oxygen under
mild reaction conditions. The developed ZnCo2O4 catalyst exhibits an appealing reaction performance with a limonene
conversion of 93.5% (reaction rate of 0.0823 mmol gcat
–1 h–1) and selectivity of 75.8% for
1,2-limonene oxide (LO), far outperforming the monometallic oxides
of ZnO and Co3O4. Detained experimental characterizations
and analyses manifest that the substitution of Zn into the Co3O4 framework can facilitate the formation of more
unsaturated coordination sites and oxygen vacancies due to the modified
chemical environment of Co atoms, inducing a beneficial synergistic
intermetallic effect for the limonene oxidation catalysis.