Water-Modulated Ru Catalysis: Overcoming the Activity-Selectivity Trade-Off in C-O Bond Cleavage.

Area of Science:

• Catalysis
• Green Chemistry
• Materials Science

Background:

• Selective catalytic C-O bond hydrogenolysis is key for valorizing lignin and its derivatives.
• Existing catalyst systems often face an activity-selectivity trade-off, limiting efficiency.
• Diphenyl ether serves as a model for strong C-O linkages in lignin.

Purpose of the Study:

• To investigate water modulation of ruthenium-based catalysts for C-O bond hydrogenolysis.
• To overcome the activity-selectivity trade-off in lignin-derived compound valorization.
• To enhance both catalytic activity and selectivity in hydrogenolysis reactions.

Main Methods:

• Utilized ruthenium supported on carbon nanotubes (Ru/CNT) as a model catalyst.
• Employed complementary characterizations, kinetic studies, and density functional theory (DFT) calculations.
• Investigated the effect of water on Ru-based catalysts with different supports (AC, TiO2).

Main Results:

• Water stabilizes Ru in an oxidized state, reducing aromatic ring interaction and inhibiting deep hydrogenation.
• Water presence lowers the C-O bond cleavage reaction barrier, significantly boosting hydrogenolysis activity.
• The activity-selectivity trade-off was successfully overcome in Ru catalysis through water modulation.

Conclusions:

• Water modulation is a facile and efficient strategy to enhance both activity and selectivity in Ru-catalyzed C-O bond hydrogenolysis.
• This approach is effective across various supports, including activated carbon (AC) and titanium dioxide (TiO2).
• The findings offer a promising pathway for the effective valorization of lignin and its oligomers.