Decomposition of alkanes at high pressures and temperatures

Abstract

The stability of methane (CH₄), ethane (C₂H₆), octane (C₈H₁₈), decane (C₁₀H₂₂), octadecane (C₁₈H₃₈), and nonadecane (C₁₉H₄₀) were studied in a CO₂-laser heated diamond anvil cell at pressures up to 25 GPa and temperatures up to about 7300 K. Methane and ethane were found to decompose to form hydrogen and diamond. Substantially greater yields of diamond were obtained from the longer chain alkanes.

Keywords:

• Alkanes
• Methane
• Decomposition
• High pressure
• High temperature

Acknowledgements

The authors thank J. Huth for preparing the SEM images. The comments of V. Hillgren are gratefully appreciated. M. R. acknowledges the support of the Alexander von Humboldt Foundation, Bonn, Germany.