EXPERIMENTAL CONFIRMATION OF THE LACK OF CARBON ISOTOPE EXCHANGE BETWEEN METHANE AND CARBON OXIDES AT HIGH-TEMPERATURES

No exchange was observed between 1. (1) CH4 and CO2 at 500°C for times as long as 136 hr; 2. (2) CH4 and CO2 in the presence of a water-containing calcium montmorillonite at 200°C up to 32 days and at 500°C up to 10.5 days; and 3. (3) CH4, CO2 and CO generated during the pyrolysis at 500°C of a natural lignite for times up to 180 hr. These experiments also indicate that the isotopic compositions of CH4, CO2 and CO found in natural environments at temperatures less than 200°C are not regulated by isotopic exchange with one another. © 1979.