Selective production of carvacrol from carvone over supported Pd catalysts

The selective conversion of biomass-derived carvone in H2 was studied over (Al2O3, C and CeO2) supported Pd (mean size 2.8-3.0 nm), taking bulk Pd as benchmark. 100% carvacrol yield was achieved over Pd/Al2O3, Pd/C and bulk Pd at an inlet H2/carvone = 1/6, with appreciably higher rates for the supported catalysts. Carveol formation over Pd/CeO2 was attributed to CO activation at surface oxygen vacancies (confirmed by O2 titration) generated during TPR. Carvotanacetone and carvomenthone formation were observed at H2/carvone > 1/6.