CO2 reforming of methane over coke-resistant Ni–Co/Si3N4 catalyst prepared via reactions between silicon nitride and metal halides

•Ni–Co/Si3N4 catalysts are prepared via reactions between metal halides and Si3N4.•Bimetallic Ni–Co nanoparticles encapsulated by a SiNx layer structures are formed.•The 4.0Ni–3.6Co/Si3N4 catalyst enables stable and coke-free CO2 reforming of CH4.

A series of Ni–Co/Si3N4 catalysts with different Ni/Co ratios were prepared via reactions between commercial silicon nitride (Si3N4) and metal halides (i.e., NiCl2 and CoF3) at high temperature (930 °C). By using X-ray diffraction and electron microscopy, it was shown that this method of catalyst preparation leads to formation of bimetallic Ni–Co nanoparticles encapsulated by a SiNx layer (Ni–Co@SiNx) on supporting Si3N4 material. The 4.0Ni–3.6Co/Si3N4 catalyst was highlighted by showing highly stable catalysis for stoichiometric CO2 reforming of methane under widely varied reaction conditions, and was found completely free of coke formation after CRM reaction for 100 h.