Acetone vapour is thermolysed (cracked) in a ketene generator, or "ketene lamp", to ketene and methane.

The process is also employed industrially for the manufacture of acetic anhydride.

Reagent for Organic Synthesis Volume 1. Fieser & Fieser, John Wiley and Sons

Reaction defined as:
Industrial Process: Organic
Radical Coupling
Radical Substitution
Thermolysis of Acetone