Ni–Mg–Al\nCatalysts for Dry Reforming\nof Methane: Effect of Surface Properties on Coke Formation and CO<sub>2</sub> Activation

Nickel-based catalysts exhibit high activity in dry reforming\nof\nmethane (DRM); however, Ni-based catalysts are susceptible to sintering\nand coke deposition, resulting in deactivation. In the present work,\na Ni–Mg–Al catalyst was prepared by reverse microemulsion\nsynthesis and used for DRM. The catalyst calcination conditions were\ncontrolled to study how the surface properties of the catalysts impact\ncoke deposition and CO<sub>2</sub> activation. The coke deposition\nspecies on the Ni–Mg–Al catalyst calcined at 700 °C\nwere amorphous carbon, and those on the Ni–Mg–Al catalyst\ncalcined at 900 °C were filamentous carbon. The strong metal–support\ninteraction enhanced at 900 °C did not prevent the formation\nof coke. The basic sites play an important role in coke deposition\nin the DRM reaction. The relationship between basic sites and CO<sub>2</sub> activation was investigated by CO<sub>2</sub>-TPD and DRIFTS.\nBidentate carbonates and monodentate carbonates led to the deposition\nof different coke types. The catalyst possesses more weak and medium\nbasic sites, which reduces the formation of filamentous carbon.