Steam and Oxysteam Reforming of Methane to Syngas over Co_xNi_(1-x)O Supported on MgO Precoated SA-5205

摘要

Catalytic steam and oxysteam refonning of methane to syngas studied involves cou- pling of exothennic oxidative conversion and endothennic steam-refonning processes over Co_xNi_(1- x)O (x = 0.0-0.5) supported on MgO precoated commercial low surface area ( < 0.01 m~2 9~(-1)) macro porous silica-alumina SA-5205 catalyst carrier. The influ- ence of the Co/Ni ratio of the catalyst on its perfonnance in steam and oxysteam refonning processes (at 800 and 850degC) was studied. For the steam refonning process, the Co/Ni ratio influences strongly on the methane and steam conversion and CO selectivity and product H_2/CO ratio, particularly at lower temperature. fJi1len the Co /Ni ratio is increased, the methane and H2O conversion and CO selectivity are decreased markedly. For the oxysteam refonning process, the influence of the Co/Ni ratio on the perfonnance is smaller and depends on process conditions. fJi1len the Co/Ni is in- creased, the methane conversion passes through a maximum at the Co/Ni ratio of 0.17. The influence of the reaction temperature (800 and 850degC) and CH_4/O_2 and CH_4/H_20 ratios on the conversion, selectivity, H_2/CO product ratio, and net reaction heat ( #DELTA#H_r) was studied in the oxysteam refonning (at space velocity of 47,000 cm~3.g~(-1).h~(-1)) ove the catalyst with an optimum Co/Ni ratio (0.17) and a higher Co/Ni ratio (1.0). The oxysteam refonning process involves coupling the exothennic oxidative conversion of methane and the endothennic methane steam refonning reactions, making the process highly energy-efficient and nonhazardous. This process can be made thennoneutral, mildly exothennic, and mildly endothennic by manipulating process conditions.