Catalytic reforming of model tar compounds from hot coke oven gas with low steam/carbon ratio over Ni/MgO–Al2O3 catalysts

The catalytic reforming of toluene and naphthalene was performed to investigate the possibility for directly converting tar components from hot coke oven gas (COG) with lower steam/carbon (S/C) molar ratios to light fuel gases. The NiO/MgO–Al2O3 catalysts reduced exhibited excellent catalytic activity, stability and sulphur tolerance. The effects of various reaction conditions and S/C ratios on the catalytic performance were investigated in detail. Toluene and naphthalene were completely converted into small gas molecules at 700–800 °C and S/C = 0.28. An appropriate amount of steam benefited the methanation reaction of CO and H2. The effects of N2, CH4 or CO in COG were also discussed. Relative to N2, CO contributed to the conversion of toluene and the formation of CH4, but the opposite was true for CH4. The sulphur tolerance was tested by adding H2S in the feed gas. The reaction results were explained by a water cycle mechanism.