Recent experiments have shown that expanding unsaturated hydrocarbons through a hot, catalytic supersonic nozzle (made of nickel or molydenum) produces larger, more saturated hydrocarbons. The pronounced non-equilibrium situation inside the nozzle prevents the formation of graphite, the equilibrium product. Recent efforts have focused on extending this technique to other reactions, including the formation of oxygen-containing compounds.
"Molecular Beam Chemistry: Formation of Benzene and Other Higher Hydrocarbons from Small Alkanes and Alkenes in a Catalytic Supersonic Nozzle"
Lina Shebaro, Sameer R. Bhalotra, Dudley Herschbach
J. Phys. Chem. 101, 6775-6780 (1997).