Improving the hydrodeoxygenation activity of vanillin and its homologous compounds by employing MoO 3 -incorporated Co-BTC MOF-derived MoCoO x @C.

Lignin-derived aryl ethers and vanillin are essential platform chemicals that fulfil the demands for renewable aromatic compounds. Herein, an efficient heterogeneous catalyst is reported for reforming vanillin via a selective hydrodeoxygenation route to 2-methoxy-4-methyl phenol (MMP), a precursor to medicinal, food, and petrochemical industries. A series of MoCoO x @C catalysts were synthesized by decorating the Co-BTC MOF with different contents of MoO 3 rods, followed by carbonization. Among these catalysts, MoCoO x @C-2 afforded ∼99% vanillin conversion and ∼99% MMP selectivity at 150 °C in 1.5 h in an aqueous medium. In contrast, CoO x @C afforded ∼75% vanillin conversion and ∼85% MMP selectivity. Detailed catalyst characterization revealed that CoO x and Co 2 Mo 3 O 8 were the active species contributing to the higher activity of MoCoO x @C-2. The excellent H 2 -adsorption characteristics and acidity of MoCoO x @C-2 were beneficial to the hydrodeoxygenation of vanillin and other homologous compounds. The DFT adsorption energy calculations suggested the favourable interactions of vanillin and vanillyl alcohol with the Co 2 Mo 3 O 8 sites in MoCoO x @C-2. The catalyst could be efficiently recycled 5 times, with a negligible loss in activity after the 5th cycle. These findings provide a systematic explication of the active sites of the mixed metal oxide-based MoCoO x @C-2 catalyst for the selective hydrodeoxygenation of vanillin to MMP, which is important for the academic and industrial catalysis community.