Direct Formation of C₃ Oxygenates through Photocatalytic CH₄-CO Coupling

Area of Science:

• Catalysis
• Chemical Synthesis
• Materials Science

Background:

• Multicarbon oxygenates (C_n, n ≥ 2) are vital industrial precursors.
• Synthesis often relies on coupling C₁ feedstocks like methane (CH₄).
• Direct coupling of more than two C₁ precursors remains challenging.

Purpose of the Study:

• To demonstrate the synthesis of acetone (CH₃COCH₃) through direct coupling of two CH₄ molecules and one carbon monoxide (CO) molecule.
• To explore a combined photothermal catalytic approach for C₃ oxygenate production.

Main Methods:

• Utilized a photothermal catalytic system with titanium dioxide (TiO₂) as the light absorber and palladium (Pd) nanoparticles as a co-catalyst.
• Conducted the reaction under 10 bar pressure and at 150 °C.
• Employed isotope-labeled precursors to confirm reaction pathways.

Main Results:

• Achieved direct synthesis of acetone from CH₄ and CO.
• Reported high selectivity for acetone formation (>80%) among liquid products.
• Identified acetic acid (CH₃COOH) as another major product from CH₄ and CO single coupling.

Conclusions:

• The study presents a proof-of-concept for synthesizing C₃ oxygenates via direct coupling of multiple C₁ feedstocks.
• Optimal binding strength of reactive intermediates on the Pd catalyst is proposed as key to high C₃ selectivity.
• This photothermal catalytic approach offers a potential route for producing valuable chemicals from abundant C₁ resources.