Ru Nanoparticles Anchored in Al ₂ O ₃ -Decorated Mesopores of MCM-41 as a Hydrogenation Catalyst

Although hexacoordinated aluminum species exhibit moderate acidity, which is advantageous for many catalytic reactions relative to the stronger acidity of tetracoordinated aluminum, their structural instability in porous frameworks significantly limits the specific surface area and pore stability of materials. To address these challenges, we report an innovative stepwise deposition strategy for constructing Al2O3/MCM-41-x materials with γ-Al2O3 decorated in the inner wall of MCM-41. The inner aluminum deposition originated from the preferential hydrolysis of AlO2– remains hexacoordinated state as γ-Al2O3 generating moderately Lewis acid sites. The outer silica deposition layer forms an MCM-41 framework, resulting in long-range ordered mesoporous material Al2O3/MCM-41 with hexagonal channels. This structure delivers a high specific surface area while simultaneously enhancing the stability of Al2O3. With Al2O3/MCM-41 as support, the optimal catalyst Ru/Al2O3/MCM-41 achieved 97.1% aniline conversion (160 °C, 3.0 MPa H2), a value three times higher than that of conventional Ru/Al2O3 (32.3%). This significant enhancement can be attributed to the synergistic effects of a high surface area, ordered mesoporous structure, and dominant Lewis acidity. This work establishes a pioneering structure featuring Al2O3 decoration in the mesopores of MCM-41 via stepwise deposition self-assembly strategy, providing a promising mesoporous support for hydrogenation catalysis and industrial applications.