Steam and oxysteam reforming of methane to syngas over Co_x Ni_1-xO supported on MgO precoated SA-5205

Abstract

Catalytic steam and oxysteam reforming of methane to syngas studied involves coupling of exothermic oxidative conversion and endothermic steam-reforming processes over Co_x Ni_1-x O (x = 0.0-0.5) supported on MgO precoated commercial low surface area (<0.01 m² g^-1) macroporous silica-alumina SA-5205 catalyst carrier. The influence of the Co/Ni ratio of the catalyst on its performance in steam and oxysteam reforming processes (at 800 and 850°C) was studied. For the steam reforming process, the Co/Ni ratio influences strongly on the methane and steam conversion and CO selectivity and product H₂/CO ratio, particularly at lower temperature. When the Co/Ni ratio is increased, the methane and H₂O conversion and CO selectivity are decreased markedly. For the oxysteam reforming process, the influence of the Co/Ni ratio on the performance is smaller and depends on process conditions. When the Co/Ni is increased, the methane conversion passes through a maximum at the Co/Ni ratio of 0.17. The influence of the reaction temperature (800 and 850°C) and CH₄/O₂ and CH₄/H₂O ratios on the conversion, selectivity, H₂/CO product ratio, and net reaction heat (Δ H_r) was studied in the oxysteam reforming (at space velocity of 47,000 cm³.g^-1.h^-1) over the catalyst with an optimum Co/Ni ratio (0.17) and a higher Co/Ni ratio (1.0). The oxysteam reforming process involves coupling the exothermic oxidative conversion of methane and the endothermic methane steam reforming reactions, making the process highly energy-efficient and nonhazardous. This process can be made thermoneutral, mildly exothermic, and mildly endothermic by manipulating process conditions.