The gas phase samples were analyzed using a gas chromatograph
(GC-Agilent Technologies 6890N) equipped with FID and
TCD detectors and the Molsieve and HP Poraplot Q columns for
methane, hydrogen, ethane, carbon monoxide, carbon dioxide,
oxygen and nitrogen analysis. The calibration with certified
calibration gases (1.5 mol% CH4, 0.987 mol% H2, 0.0493 mol%
C2H6, 2.02 mol% CO, and 99.999 mol% CO2) was performed before
each experimental run.