Selective hydrogenation of cinnamaldehyde over magnetic flower-like carbonaceous Pd catalysts†
Abstract
Synthesis of an easily separable and efficient catalyst is of great significance for selective hydrogenation of unsaturated functional groups. In this work, novel magnetic flower-like carbonaceous Pd catalysts are constructed for the selective reduction of the CC bond. According to the characterization results, a flower-like architecture is observed in the catalysts containing both Fe3O4 and Pd NPs, which is constructed by the secondary self-assembly in the preparation process due to the interaction between Pd and magnetic nitrogen-doped graphene (Fe3O4-NG). More flower-like structures are formed by increasing the Pd loading amount, further enhancing the specific surface area of the catalyst. The specific surface area of Pd-FONG-3 is the highest (521.17 m2 g−1). Combining the results of characterization and experiments, it is found that the catalytic activity is positively related to the flower-like architecture and the interaction between Pd NPs (6.0 nm) and Fe3O4 NPs (6.7 nm). Fe3O4 is not only beneficial to the magnetic recovery of the catalyst, but also acts as a cocatalyst, which can significantly improve the reactant conversion. Moreover, N species play an important role in protecting the C
O bond, resulting in the selective hydrogenation of the C
C group. Herein, Pd-FONG-3 exhibits excellent activity in the selective hydrogenation of cinnamaldehyde (CAL) with 99.5% conversion and 96.5% hydrocinnamaldehyde (HCAL) selectivity, and its catalytic performance is much better than that of the commercial 5% Pd/C catalyst (100% conversion and 69.1% HCAL selectivity). This work provides a new strategy to construct highly active catalysts with magnetic recovery properties for selective hydrogenation of C
C bonds, and Pd-FONG-3 shows tremendous application foreground.