Investigation into the mechanism of NiMg(Ca)bAlcOx catalytic activity for production of solarised syngas from carbon dioxide reforming of methane

A series of NiMg(Ca)bAlcOx catalysts prepared by co-precipitation were investigated for carbon dioxide reforming of methane at 750 °C and one atmosphere to determine the mechanism of these catalysts’ activity. X-ray diffraction, scanning electron microscopy combined with energy dispersive X-ray analysis and temperature programmed reduction showed that Ni–Mg–Al–O solid solution formed in the catalysts. NiMg3AlOx exhibited excellent performance with a stable CH4 conversion rate of 3.3854 × 10−3 (mol/g cat/s), due to the formation of Ni–Mg–Al–O solid solution with a high proportion of Ni–Mg–O, and an optimum proportion of weak to intermediate to strong basic sites. Changing the Mg/Al atomic ratio of NiMgbAlcOx affects these catalysts’ performance. Replacing Mg in NiMg3AlOx with Ca obviously reduces catalyst activity and stability, because of a lack of Ni–Mg solid solution and a smaller Brunauer–Emmett–Teller specific surface area.