Sunlight Powered Continuous Flow Reverse Water Gas Shift Process Using a Plasmonic Au/TiO₂ Nanocatalyst

Area of Science:

• Materials Science
• Catalysis
• Renewable Energy

Background:

• The reverse water gas shift (rWGS) reaction is crucial for producing syngas from CO2 and H2.
• Developing efficient and sustainable catalysts for rWGS is essential for carbon utilization and energy storage.

Purpose of the Study:

• To investigate the use of a plasmonic Au/TiO2 nanocatalyst for solar-driven continuous flow rWGS.
• To understand the effect of catalyst bed thickness on CO production and identify catalytic regimes.
• To optimize reaction conditions and assess catalyst stability and performance.

Main Methods:

• Synthesis and characterization of plasmonic Au/TiO2 nanocatalyst.
• Continuous flow rWGS experiments using sunlight as the sole energy source.
• Systematic variation of catalyst bed thickness to study reaction kinetics.
• Optimization of CO2:H2 ratio and evaluation under varying light intensities and pressures.

Main Results:

• Identified three catalytic regimes: direct plasmon catalysis (DPC), shielded plasmon catalysis (SPC), and unused plasmon catalysis (UPC).
• Achieved a maximum CO production rate of 7420 mmol·m⁻²·h⁻¹ at a CO2:H2 ratio of 4:1 under mild conditions (3.5 bar, no external heating).
• Demonstrated catalyst stability over 110 hours of continuous operation, retaining >82% of initial CO production, and stability over 8 on/off cycles.

Conclusions:

• Plasmonic Au/TiO2 nanocatalysts are highly effective for solar-driven rWGS reactions.
• Catalyst bed thickness significantly influences reaction efficiency, defining distinct catalytic regimes.
• The developed system offers a sustainable and stable pathway for CO production using renewable energy.