MOF-templated core-shell Co(II/III)@ZnO hexagonal prisms for selective oxidation of vanillyl alcohol

This work provides a facile strategy to prepare core-shell structured catalysts with MOF-templated metal active species embedded carbon matrix core and a functional metal oxide shell in a controllable way. The procedure features with the facile introduction of functional shell metal oxide and delivery of MOF morphology. Co(II/Ⅲ)@ZnO hexagonal prisms are fabricated with this procedure and ZIF-67 as the template. When being used in the selective oxidation of vanillyl alcohol to produce vanillin, ZnO shell plays an important role by faciliating redox of Co 3+ /Co 2+ for promoting vanillyl alcohol oxidation to vanillin and protecting the Co species against leaching into the reaction system. Co(II/Ⅲ)@ZnO exhibits a conversion of 20% with a selectivity of 80% after a 2 h reaction and shows stability after 3 catalytic cycles.