Iron-catalyzed CO2 hydrogenation as a mechanism for coalbed gas formation

Iron-catalyzed CO2 hydrogenation is proposed as a mechanism that occurs during natural gas formation in coalbeds. This reaction was studied in a laboratory batch reactor at temperatures simulating geologic conditions. The percentage of methane in the produced gas was typically greater than 90%, resembling natural gas composition. Fe2O3, the precursor to the active catalyst, was reduced at 200°C under a hydrogen atmosphere. Mِssbauer spectroscopy shows that under those conditions ca. 6% of the iron oxide is reduced to the metal, which is believed to be the catalytically active species. Addition of water to the reactor increased the generation of methane. No signs of deactivation were found under either dry or wet conditions. Evidence supporting the possibility that this reaction produces natural gas during coal maturation is provided.