Effect of three processes on CO2 and O2 simultaneously reforming of coke oven gas to syngas

• CO2 and O2 simultaneously reforming of coke oven gas to syngas.
• Compare non-catalytic process (NCP), catalytic process (CP), two-stage process (TSP).
• A bit of O2 promotes CO2 conversion in NCP and restrains CO2 conversion in CP and TSP.
• The TSP precedes NCP and CP in the reforming of COG via two-stage reactions.
• TSP couples H2 oxidation in first-stage with CH4 reforming and RWGS in second-stage.

CO2 and O2 simultaneously reforming of coke oven gas (COG) in three processes including non-catalytic process (NCP), catalytic process (CP), and two-stage process (TSP) was investigated under two important operating conditions, CO2/CH4 and O2/CH4, over Ni-based catalyst in a fixed bed reactor. It was found that the technical indexes depend strongly on CO2/CH4 and O2/CH4 in different processes. CO2 can adjust H2/CO ratio in a wider range (0.52–3.83) in the presence of O2. The conversions of CH4 increase in overall COG reforming processes by adding O2. Also, a little O2 promotes CO2 conversions in NCP and restrains CO2 conversions in CP and TSP. The addition of O2 can also adjust H2/CO ratio of syngas, which is actually at the cost of H2 consumption by oxidation rather than reverse water gas shift (RWGS) reaction. In addition, H2 combustion in the first-stage of TSP provides heat to drive the endothermic CH4 reforming reactions and RWGS reaction in the second-stage of TSP to achieve higher CH4 and CO2 conversions. Therefore, TSP precedes significantly NCP and CP in the reforming of COG. When H2/CO ratio is 2.10, the conversions of CH4 and CO2 are 98.96 and 62.32% respectively; and, oxygen consumption is 0.13 m3 per COG m3 at gas hour space velocity 9256 h−1 in TSP.