Unraveling role of oxygen vacancies in catalytic deoxygenation of biomass-derived carboxylic acids over ceria

Catalytic deoxygenation by ceria (CeO 2 ) represents an effective approach for upgrading bio-oil, yet the relationship between oxygen vacancies (O V ) of CeO 2 and catalytic ability remains controversial. To address this issue, three CeO 2 samples calcined in different atmospheres were adopted in catalytic deoxygenation of n -octanoic acid. Characterization results revealed that these CeO 2 exhibited identical crystal structure and different O V contents and surface acid-base properties. Catalytic tests demonstrated that O 2 -calcined CeO 2 primarily promoted ketone production at 400–600 °C while facilitated the formation of alkenes and aromatics at 600 °C. For the three CeO 2 catalysts, the highest O V content in H 2 -calcined CeO 2 endowed it with optimal acid-base pairs for enhancing both ketonization and aromatization reactions, thus achieving superior deoxygenation performance. Density functional theory calculations confirmed that O V significantly reduced the adsorption energy of active species during ketonization. This study provides evidence that surface O V of CeO 2 boost deoxygenation activity by optimizing acid-base pair sites.