where FH2O; out stands for the molar flow rate of water at the exit of
the reactor. Unlike the methane conversion (Fig. 3a), Fig. 5 depicts
that the H2 yield and selectivity decrease from 0.90 to
0.71 mol(mol CH4)1 and from 74.54 to 60.33%, respectively,
when the CO2/O2 ratio increases from 0 to 2. These results imply
that the H2 yield and selectivity are sensitive to CO2 addition. The
drop in H2 flow rate (Fig. 4a) and yield (Fig. 5a) with increasing
CO2/O2 ratio is due to the deterioration of methane conversion
(Fig. 3a) and H2 selectivity (Fig. 5b). In view of the increase in CO
formation and decrease in H2 generation with increasing CO2/O2
ratio (Fig. 4a), the H2/CO ratio goes down (Fig. 5c) when more CO2
is fed into the reactor.