Assembling a Metastable Electron Fence within Gold-Zeolite Interfaces for Boosted Propylene Epoxidation

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Selective oxidation of hydrocarbons is crucial for the chemical industry but faces challenges in achieving high activity and selectivity.
• Conventional gold (Au) catalysts exhibit good resistance to overoxidation but suffer from poor oxygen activation.

Purpose of the Study:

• To develop an enhanced gold/zeolite catalyst with improved oxidation performance using an
• electron fence
• strategy.
• To overcome the limitations of poor oxygen activation and enhance selectivity in hydrocarbon oxidation reactions.

Main Methods:

• Engineered a metastable "Hamburger" heterostructure by controlling the reduction dynamics and phase separation of immiscible Au-Rh precursors.
• Intercalated Rh atomic layers at the Au-zeolite interface to create an electron fence, confining electrons within Au and enabling a valence-state transition.
• Fine-tuned the Au-Rh ratio to prevent catalyst restructuring and control selectivity.

Main Results:

• Achieved a record-breaking propylene epoxidation rate of 502.6 g·kg_cat^-1·h^-1, a two-order-of-magnitude enhancement.
• The electron fence strategy successfully addressed hydrogen and oxygen activation challenges, promoting hydroperoxyl radical generation.
• Demonstrated prevention of overhydrogenation and overoxidation through precise control of catalyst structure and composition.

Conclusions:

• The developed electron-fence Au-Rh catalyst significantly enhances activity and selectivity in propylene epoxidation.
• The electron-fence strategy offers a promising approach for designing advanced catalysts for selective oxidation reactions.
• This strategy shows potential for extension to other reactions, such as propane hydro-oxidation to acetone.