Performance and Stability of Corundum-type In₂O₃ Catalyst for Carbon Dioxide Hydrogenation to Methanol

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Carbon dioxide hydrogenation to methanol is crucial for energy storage.
• Indium oxide is a promising alternative to copper/zinc oxide catalysts for CO2 reactions.
• Current indium oxide catalysts require optimization for stability and performance.

Purpose of the Study:

• To synthesize and evaluate indium oxide catalysts with varying rhombohedral and cubic phase ratios.
• To understand the phase stability of indium oxide under reaction conditions.
• To identify optimal catalyst design and operating conditions for efficient methanol synthesis.

Main Methods:

• Solvothermal synthesis of indium oxide catalysts with different phase ratios.
• Evaluation in a mixed gas phase reactor.
• In situ synchrotron X-ray diffraction (XRD) and Rietveld refinement for phase stability analysis.

Main Results:

• Pure rhombohedral indium oxide exhibited superior methanol yield, selectivity, and stability.
• A rhombohedral to cubic phase transition was observed under specific operating conditions (flow rate, temperature, hydrogen pressure).
• Cubic indium oxide can act as nuclei, promoting detrimental phase transitions to inactive metallic indium.

Conclusions:

• The rhombohedral phase of indium oxide is optimal for stable and efficient carbon dioxide hydrogenation to methanol.
• Careful control of operating conditions is essential to prevent phase transitions and catalyst deactivation.
• Rational catalyst design should prioritize the rhombohedral phase and avoid cubic In2O3 to ensure long-term performance.