Accelerated Cascade Partial Hydrogenation−Hydrolysis− Hydrogenation of Alkoxylbenzenes to Cyclohexanols over Oxidized Mo ₂ Ti ₂ C ₃ MXene with <i>In Situ</i> Metal−Acid Pairs

Developing a cascade partial hydrogenation−hydrolysis−hydrogenation route for converting alkoxylbenzenes to cyclohexanols is crucial for high-value bio-based chemical synthesis. However, it remains challenging because of competing hydrogenolysis and full hydrogenation side reactions. Herein, we report an oxidized Mo2Ti2C3 MXene with abundant Mo−C and Mo−O sites that exhibits a high cyclohexanol yield of 99.3% from methoxylbenzene under mild reaction conditions at 50 °C. Mechanistic investigations revealed that hydrogen spillover from Mo−C to Mo−O sites generates Brønsted acidic Mo/Ti−O−Hδ+ species. The in situ-generated proximal metal−acid (Hδ+) pairs ensure that partially hydrogenized methoxylcyclohexene intermediates are rapidly transferred from Mo−C hydrogenation sites to Mo/Ti−O−Hδ+ acidic sites, ultimately accelerating the cascade partial hydrogenation−hydrolysis−hydrogenation route to cyclohexanol. Moreover, the catalyst exhibits a broad substrate scope, enabling the conversion of various alkoxylbenzenes into their corresponding cyclohexanols. This study presents powerful bifunctional catalysis enabled by in situ-generated proximal metal−acid pairs over oxidized Mo2Ti2C3 MXene, offering an effective strategy for the challenging cascade transformation of alkoxylbenzenes into cyclohexanols.