Ni–Mg–Al Catalysts for Dry Reforming of Methane: Effect of Surface Properties on Coke Formation and CO₂ Activation

Nickel-based catalysts exhibit high activity in dry reforming of methane (DRM); however, Ni-based catalysts are susceptible to sintering and coke deposition, resulting in deactivation. In the present work, a Ni–Mg–Al catalyst was prepared by reverse microemulsion synthesis and used for DRM. The catalyst calcination conditions were controlled to study how the surface properties of the catalysts impact coke deposition and CO2 activation. The coke deposition species on the Ni–Mg–Al catalyst calcined at 700 °C were amorphous carbon, and those on the Ni–Mg–Al catalyst calcined at 900 °C were filamentous carbon. The strong metal–support interaction enhanced at 900 °C did not prevent the formation of coke. The basic sites play an important role in coke deposition in the DRM reaction. The relationship between basic sites and CO2 activation was investigated by CO2-TPD and DRIFTS. Bidentate carbonates and monodentate carbonates led to the deposition of different coke types. The catalyst possesses more weak and medium basic sites, which reduces the formation of filamentous carbon.