Tuning CO₂ Hydrogenation Selectivity through Reaction-Driven Restructuring on Cu-Ni Bimetal Catalysts

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Tuning carbon dioxide (CO2) hydrogenation selectivity is crucial for producing valuable chemicals.
• Nickel-based catalysts are promising but require modification to control product distribution.
• CO is a key intermediate, and nickel's oxidation state influences selectivity.

Purpose of the Study:

• To synthesize and evaluate Cu-Ni bimetallic nanoparticles for selective CO2 hydrogenation to CO.
• To understand the structure-activity relationship governing the catalytic performance.
• To enhance CO selectivity while maintaining high CO2 conversion rates.

Main Methods:

• Hydrothermal synthesis of monometallic (Ni, Cu) and bimetallic (Cu-Ni) nanoparticles supported on γ-Al2O3.
• Catalytic performance evaluation using a continuous fixed-bed flow reactor.
• Surface characterization using ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and in situ diffuse reflectance infrared Fourier-transform spectroscopy (in situ DRIFTS).

Main Results:

• The Cu0.5Ni0.5/γ-Al2O3 catalyst exhibited high CO2 conversion and superior CO selectivity compared to monometallic catalysts.
• In situ studies revealed Cu migration and restructuring to a Cu-Ni alloy during reaction, enhancing CO desorption.
• A clear correlation was established between surface electronic structure and catalytic activity.

Conclusions:

• Cu-Ni bimetallic nanoparticles effectively tune CO2 hydrogenation selectivity towards CO.
• Surface restructuring and the formation of a Cu-Ni alloy are key to enhanced catalytic performance.
• This study provides a strategy for designing selective catalysts by modifying bimetallic nanoparticle surface structures.