Fe2O3 aided NiFe2O4 enhanced CO2 hydrogenation to CO

NiFe 2 O 4 has been widely applied in CO 2 hydrogenation for its excellent redox properties. However, NiFe 2 O 4 samples usually exhibited complex performance, rapid inactivation followed by slow activation, and poor hydrogenation selectivity. In this work, the complex behavior of NiFe 2 O 4 in CO 2 hydrogenation was studied, and the influence of surface oxide species(NiO and Fe 2 O 3 ) on its catalytic performance was probed on NiFe 2 O 4 -ww through magnetic water washing. NiFe 2 O 4 -ww was observed to predominantly produce CO with nearly 100% selectivity at lower temperatures and demonstrated a higher CO 2 conversion rate of 71.90% at 700 °C. However, under high-temperature reducing conditions, NiFe 2 O 4 -ww underwent rapid reduction to form Fe Ni alloy, which induced sintering and carbon deposition, thereby leading to a significant decline in catalytic activity. Surface NiO species on NiFe 2 O 4 enhanced CO 2 hydrogenation at lower temperatures but reduced the selectivity towards CO. Surface Fe 2 O 3 species enhanced the catalytic resistance to reduction, thereby improving catalyst stability by inhibiting the accumulation of carbon deposition. The effect of residual oxides on the NiFe 2 O 4 surface may give insight into understanding the deactivation behavior of Fe Ni alloy in CO 2 hydrogenation.