Abstract
The different effects of the presence of La3+ and Sm3+ heteroatoms in the 5 wt% Ni/45Ce-45(Sm or La)-10Cu-O catalytic system on the carbon deposition and removal reaction paths in the dry reforming of methane (DRM) at 750 °C were investigated using transient kinetic and isotopic experiments. The relative initial rates of carbon oxidation by lattice oxygen of support and that by oxygen derived from CO2 dissociation under DRM reaction conditions were quantified. Ni nanoparticles (23-nm) supported on La 3+-doped ceria exhibited at least 3 times higher initial rates of carbon oxidation to CO by lattice oxygen, and ~ 13 times lower rates of carbon accumulation than Ni (18-nm) supported on Sm3+-doped ceria. The concentration and mobility of labile surface oxygen at the Ni-support interface region seems to correlate with carbon accumulation. Ni/Ce-La(or Sm)-–10Cu-O formed NiCu alloy nanoparticles, partly responsible for lowering carbon deposition and increasing carbon oxidation rates to CO.
[Display omitted]
•H2 treatment of Ni/Ce-La(Sm)-Cu-O at 750 °C leads to Cu exsolution and alloying with Ni.•CH4 decomposition is the dominant path of carbon deposition in DRM at 750 °C.•Ni/Ce-La-Cu-O largely decreases carbon accumulation via CH4 decomposition compared to Sm3+ counterpart.•Ni/Ce-La-Cu-O promotes to a greater extent carbon oxidation by lattice oxygen compared to Sm3+ counterpart.•Carbon oxidation by lattice oxygen in Ni/Ce-La(Sm)-Cu-O is faster than that by oxygen via CO2 (initial DRM).