Engineering Iron-Nickel Nanoparticles for Magnetically Induced CO2 Methanation in Continuous Flow

Abstract

Induction heating of magnetic nanoparticles (NPs) is a method to activate heterogeneous catalytic reactions. It requires nano-objects displaying high heating power and excellent catalytic activity. Here, using a surface engineering approach, bimetallic NPs are used for magnetically induced CO₂ methanation, acting both as heating agent and catalyst. The organometallic synthesis of Fe₃₀ Ni₇₀ NPs displaying high heating powers at low magnetic field amplitudes is described. The NPs are active but only slightly selective for CH₄ after deposition on SiRAlOx owing to an iron-rich shell (25 mL min^-1 , 25 mT, 300 kHz, conversion 71 %, methane selectivity 65 %). Proper surface engineering consisting of depositing a thin Ni layer leads to Fe₃₀ Ni₇₀ @Ni NPs displaying a very high activity for CO₂ hydrogenation and a full selectivity. A quantitative yield in methane is obtained at low magnetic field and mild conditions (25 mL min^-1 , 19 mT, 300 kHz, conversion 100 %, methane selectivity 100 %).

Keywords: CO2 methanation; heterogeneous catalysis; iron-nickel; magnetic properties; nanoparticles.