Catalytic cracking of n-hexane over MoO₂

Catalytic cracking reactions of n-hexane over molybdenum oxide (MoO₂) grown on a polycrystalline molybdenum foil (∼1 cm²) were studied in the temperature range 830-913 K at a low conversion (<2%). The n-hexane pressure was 7.3 Torr. The reactions were carried out in a batch reactor and no hydrogen or water vapor (steam) was used. The cracking products of n-hexane were mostly alkenes-ethylene (29 mol%), propylene (35 mol%), butenes (19 mol%) and pentenes (5 mol%)along with small amounts of alkanes-methane (7 mol%), ethane (4 mol%) and propane (1 mol%). The apparent activation energy for the catalytic cracking of n-hexane was ∼60 kcal/mol. The reaction rates were not deactivated over more than 5 h of use. Dehydrogenation and aromatization were also observed, but these reactions rates decreased as the gas inside the batch reactor reached an equilibrium. Auger and X-ray photoelectron spectroscopy studies suggested an oxycarbide form as the catalytically active phase.