Efficient hydrogenation of fatty acids to fatty alcohols and alkanes over Fe@Fe3O4 catalysts with rich oxygen vacancies and Lewis acid sites

The development of non-noble metal catalysts for the selective hydrogenation of long-chain fatty acids into value-added chemicals remains a significant challenge. Here, an efficient Fe@Fe 3 O 4 catalyst enriched with oxygen vacancies and weak Lewis acid sites was obtained by tuning the reduction temperature. The catalyst enabled complete conversion of stearic acid with a 97.3 % yield of octadecanol under mild conditions, and maintained high activity after 19 cycles. Moreover, when stearic acid was completely converted to alkanes, the yield of octadecane via the hydrodeoxygenation pathway (97.4 %) was markedly higher than that of heptadecane via the decarbonylation pathway (2.6 %), indicating the catalyst's excellent carbon atom utilization efficiency. Mechanistic studies revealed that metallic Fe efficiently dissociates H 2 to generate active hydrogen, while oxygen vacancies and weak Lewis acid sites in Fe 3 O 4 promote carbonyl adsorption and activation. In addition, weak Lewis acid sites interact with the carbonyl oxygen to moderately polarize the C O bond, thereby suppressing undesired C C cleavage. These synergistic effects account for the catalyst's high activity and selectivity, providing guidance for the design of advanced non-noble metal catalysts for fatty acid hydrogenation.