“…This result corresponds to 0.07 tons of H 2 produced per ton of steel mill gas (65 % CO, 15 % CO 2 ) or 100 % of the theoretical H 2 yield. Another study on the effect of high CO partial pressures, reported that the highest H 2 production rates were detected between 6 and 24 h of cultivation for the 50 % CO culture and between 24 and 48 h for the 75 % and 100 % CO culture (Díaz et al, 2022). However, in the current experiment (65 % CO), the highest H 2 production rates were observed at 24 h and thereafter they declined rapidly.…”