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.