Partial oxidation of methane to syngas with or without simultaneous steam or CO2 reforming over a high-temperature stable-NiCoMgCeOx supported on zirconia–hafnia catalyst

A NiCoMgCeOx (Ni/Co/Mg/Ce:1:0.2:1.2:1.2)/zirconia–hafnia catalyst with unusually high thermal stability has been investigated for syngas generation via a process that includes the catalytic partial oxidation of methane (CPOM), the oxidative steam reforming of methane (OSRM) and the oxidative CO2 reforming of methane (OCRM). The catalyst calcined at 1400 °C (for 4 h) showed excellent activity/selectivity for the CPOM, OSRM and the OCRM reactions; furthermore no catalyst deactivation was observed for a period of 20 h. For the CPOM process, the selectivity for H2 was >95% at reaction temperatures ≥650 °C; however temperatures above 800 °C were required to achieve >95% CO selectivity. While the reaction temperature had a considerable influence on the CPOM product H2/CO ratio, the space velocity (at 850 °C) did not affect it to any significant extent. For the OSRM process, the H2O/CH4 ratio and the reaction temperature had a strong effect on the product H2/CO ratio and the heat of the reaction; depending on the H2O/CH4 ratio and reaction temperature, the OSRM process could be operated in a mildly exothermic, thermoneutral or mildly endothermic mode. The CO2 conversion was very strongly affected by the reaction temperature in the OCRM process; reasonably high CO2 conversion (>40%) could only be obtained at high OCRM reaction temperatures (>850 °C). The exothermicity of the OCRM reaction was found to decrease with increasing reaction temperature.