High-Temperature Calcination Improves Catalytic Activity and Stability of Ce-Doped Ni/MgO Nanocatalysts for Dry Reforming of Methane

Dry reforming of methane (DRM) offers a promising strategy that concomitantly converts two greenhouse gases (CH 4 and CO 2 ) into valuable syngas (H 2 and CO). Ni is a commonly used active metal component in DRM catalysts, while catalyst deactivation stemming from carbon accumulation and sintering remains a great challenge. Ensuring the availability of adequate active oxygen species to promote CH x ( x = 0∼3) oxidation and inhibit particle aggregation is generally critical to prevent catalyst deactivation. Our study applied a simple coprecipitation method to synthesize Ni/Ce x MgO catalysts for the DRM reaction, while the calcination temperatures have been first found to play an important role in controlling their catalytic performance. Interestingly, with higher temperature treatment, the Ni/Ce 0.005 MgO-800 catalyst with a certain amount of Ce doping exhibited the greatest activity (conversion of 73.5% for CH 4 and 82.3% for CO 2 at 750 °C under a weight hourly space velocity of 30,000 mL·g cat –1 ·h –1 ). Moreover, the catalytic activity can remain stable within 40 h running at 750 °C, and no carbon accumulation was detected on the used catalyst. A series of characterization results showed that both increasing the calcination temperature and Ce doping can increase the weakly basic sites and oxygen vacancy of the catalyst, thereby intensifying the adsorption and activation capabilities for CO 2 and generating more reactive oxygen species, accelerating the removal of unexpected deposited carbon. Meanwhile, the higher calcination temperature might promote electron transfer between Ni, Mg, and Ce, consequently strengthening the metal–support interaction and inhibiting the sintering of Ni.