Hexacoordinate Ti-Anchored Single-Atom Pd Catalyst for High-Efficiency Cyclohexanone Ammoximation with H₂ and O₂

Area of Science:

• Catalysis
• Materials Science
• Green Chemistry

Background:

• Cyclohexanone oxime is typically produced using hydrogen peroxide.
• Existing catalysts suffer from inefficient precious metal utilization and suboptimal titanium activity.
• Developing sustainable alternatives for cyclohexanone oxime synthesis is crucial.

Purpose of the Study:

• To develop a novel bifunctional catalyst for cyclohexanone oxime production via ammoximation.
• To enhance precious metal utilization and titanium activity in composite catalysts.
• To establish a green and sustainable method for cyclohexanone oxime synthesis.

Main Methods:

• One-step synthesis of a Pd@Ti-MWW-PI catalyst using Ti-MWW zeolite support.
• Anchoring piperidine-modified palladium single atoms on hexacoordinated framework-titanium via Pd-O-Ti bonds.
• Utilizing hydrogen and oxygen for the ammoximation of cyclohexanone in water.

Main Results:

• Achieved a record cyclohexanone oxime formation rate of 13000 mol molPd−1 h−1 with ultralow Pd loading (0.02 wt %).
• Demonstrated exceptional catalyst stability, maintaining >99% selectivity for over 2500 hours in continuous operation.
• Successfully employed water as a solvent, highlighting environmental sustainability.

Conclusions:

• The Pd@Ti-MWW-PI catalyst represents a significant advancement in H2/O2-mediated ammoximation.
• This work offers a practical and environmentally friendly route for cyclohexanone oxime production.
• The developed catalyst design strategy can be applied to other catalytic systems.