Lanthanide oxide supported Ni nanoparticles for the selective hydrogenation of cinnamaldehyde

NiO-LnO_x (Ln = La, Ce or Pr) precursors were prepared using a sol-gel method with glucose as a template, and the corresponding Ni/LnO_x catalysts were obtained by reduction in hydrogen at 500 °C. When applied to the selective hydrogenation of cinnamaldehyde (CAL), the Ni/La₂O₃ catalyst exhibited superior behavior to Ni/Pr₆O₁₁ and Ni/CeO₂, affording 90.2% selectivity to hydrocinnamaldehyde (HCAL) with an initial activity of 0.57 s⁻¹ under mild conditions. Various characterization techniques confirmed that the formation of the perovskite LaNiO₃ precursor enhanced the interaction of Ni species with lanthanum species, and effectively avoided the agglomeration of Ni nanoparticles during the reduction. Hence, Ni nanoparticles could achieve high and uniform dispersion. Moreover, the C O group in CAL was preferentially adsorbed and fixed by weak and medium-strong basic sites (La³⁺-O²⁻) on the Ni/La₂O₃ catalyst, so that the chemisorption of the C C bond on active Ni nanoparticles becomes more favorable and thus the corresponding selective hydrogenation of the C C bond dominates.