Carbon-encapsulated FeNi nanoparticles for efficient magnetically induced levulinic acid hydrogenation

Abstract

Developing robust and efficient catalysts for magnetic induction heating (MIH) offers a sustainable approach for biomass valorization under mild conditions. Herein, we report a green and scalable synthetic method to prepare FeNi-based magnetic nanoparticles (MagNPs), with different atomic compositions, encapsulated in N-doped graphitic carbon (Fe₁Ni_X@N-G), via single-step pyrolysis of glucose and urea. These bimetallic nanoparticles serve both as efficient heating agents and active catalysts. Among them, Fe₁Ni_0.25@N-G demonstrated excellent catalytic performance in the magnetically induced hydrogenation of levulinic acid (LA) in aqueous solution, achieving full conversion and complete selectivity to γ-valerolactone (GVL) under mild conditions (63 mT, 320 kHz, 2 kW). Furthermore, the reactivity of Fe₁Ni_0.25@N-G was tested in the magnetically induced hydrogenation of other biomass-derived substrates of interest, such as 5-hydroxymethylfurfural (HMF), levoglucosenone, and vanillin, showing good activity and selectivity in all cases under mild reaction conditions. Finally, the robust encapsulation of the FeNi NPs in N-doped graphitic carbon strongly improved the stability of the catalyst in aqueous media, enabling its reuse up to four times under acidic conditions (pH ∼2), for LA hydrogenation, and up to eight times under neutral conditions, such as HMF.