Oxy-CO2 Reforming and Oxy-CO2 Steam Reforming of Methane to Syngas over COxNi1−xO/MgO/SA-5205

Abstract

Oxy-CO2 reforming and simultaneous oxy-CO2 and steam reforming of methane, involving coupling of exothermic oxidative conversion and endothermic steam and/or CO2 reforming of methane over CoxNi1_xO(14 ± 0.5 wt%)/MgO (7.6 wt%)/SA-5205 (x = 0.0 – 0.5) catalysts (where SA-5205 is a sintered low surface area macroporous silica-alumina catalyst carrier, obtained from Norton, USA) have been thoroughly investigated. Effect of Co/Ni ratio of the catalyst on its performance in these two methane-to-syngas conversion processes has been studied. For the oxy-CO2 reforming process, the Co/Ni ratio has a strong influence on the conversion of methane and CO2 and also on the selectivity for H2. The optimum Co/Ni ratio for this process was found to be 0.17. However, for the simultaneous oxy-CO2 and steam reforming process, Co/Ni ratio has a strong influence on the conversion of CO2 and H2O, depending upon the process conditions, but has a little or no influence on the methane conversion and the H2/CO ratio. Hence, in this process, the catalyst with Co/Ni ratio of 1.0, which has lower activity for the filamental carbon formation, is more preferable. In this process (at 850°C), the catalyst (with Co/Ni =1.0) shows very high methane conversion activity (97% conversion) and 100% selectivity (based on methane) for both CO and H2 at a low contact time (15 ms) and the H2/CO ratio can be controlled by manipulating the CO2/H2O feed ratio. In both the processes, the exothermic oxidative conversion and endothermic steam and/or CO2 reforming reactions over the catalyst occur simultaneously, involving coupling of the exothermic and endothermic reactions. Because of this, these processes are highly energy efficient and also non-hazardous or safe to operate. Moreover, by manipulating the process conditions [viz., temperature and CH4/O2 feed ratio], these processes can be made mildly endothermic, near thermoneutral or mildly exothermic.