Combined H2O and CO2 reforming of coke oven gas over Ca-promoted Ni/MgAl2O4 catalyst for direct reduced iron production

Ca-promoted Ni/MgAl2O4 catalysts prepared by co-impregnation method with different Ca/Ni ratios of 0.0-1.0 were applied to syngas production for direct reduced iron via the combined H2O and CO2 reforming (CSCR) of coke oven gas (COG). The physicochemical properties of prepared catalysts were characterized by XRD, BET, H2-chemisorption, TPR and CO2-TPD. The SEM, TGA and TEM analysis was carried out to observe the coke deposition and agglomeration of Ni particle in used catalysts. It was confirmed that Ca addition improved the Ni dispersion, strong metal-support interaction (SMSI) and CO2 adsorption of catalyst. The CSCR of COG was carried out under the reaction conditions of CH4:H2O:CO2:H2:CO:N2 = 1:1.2:0.4:2:0.3:0.3, 700-900 °C, 5 atm. The Ca-promoted 10Ni/MgAl2O4 catalysts show higher CH4 conversion and coke resistance than 10Ni/MgAl2O4 catalyst without Ca addition. In particular, 10Ni-5Ca/MgAl2O4 catalyst with Ca/Ni ratio of 0.5 showed a good catalytic activity and sinter-stability in CSCR of COG at high temperature of 900 °C due to high Ni dispersion and improved SMSI.