Iron-catalyzed CO2 hydrogenation is proposed as a mechanism that occurs dur
ing natural gas formation in coalbeds. This reaction was studied in a labor
atory batch reactor at temperatures simulating geologic conditions. The per
centage of methane in the produced gas was typically greater than 90%, rese
mbling natural gas composition. Fe2O3, the precursor to the active catalyst
, was reduced at 200 degrees C under a hydrogen atmosphere. Mossbauer spect
roscopy shows that under those conditions ca. 6% of the iron oxide is reduc
ed to the metal, which is believed to be the catalytically active species.
Addition of water to the reactor increased the generation of methane. No si
gns 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. (C) 1999 Elsevier Science Ltd. All rights rese
rved.