A hybrid terpyridine ligand was designed to functionalize a magnetic support constituted of magnetite cores surrounded by a silica shell with the aim of improving the stabilization of supported-palladium nanoparticles for the later application of the obtained composite nanomaterial in hydrogenation catalysis. The preparation of the nanomaterial was performed by direct decomposition of the organometallic complex [Pd2(dba)3] on the terpyridine-modified magnetic support providing well-dispersed Pd NPs of 2.5 ± 0.6 nm mean size. This new nanomaterial is a highly active catalyst for the hydrogenation of cyclohexene under mild conditions reaching turnover frequencies up to ca. 58 000 h−1 or 129 000 h−1 when corrected for surface Pd atoms. Furthermore, in the hydrogenation of β-myrcene, this nanocatalyst is highly selective for the formation of monohydrogenated compounds. When compared to a similar nanocatalyst consisting of palladium nanoparticles supported on an amino-modified magnetic support or on Pd/C, the activity and selectivity of the nanocatalyst are largely increased. These results show how the design of an appropriate hybrid ligand used to functionalize the support can strongly influence the catalytic properties of supported metal nanoparticles.
我们设计了一种混合萜
吡啶配体来对由磁
铁矿核和
二氧化硅壳构成的磁性支撑物进行功能化,目的是提高支撑
钯纳米粒子的稳定性,以便日后将获得的复合纳米材料应用于氢化催化。这种纳米材料的制备方法是将有机
金属复合物[Pd2(dba)3]直接分解在terpyridine修饰的磁性载体上,从而得到平均粒径为2.5 ± 0.6 nm的分散良好的
钯纳米粒子。这种新型纳米材料是一种高活性催化剂,可在温和条件下催化
环己烯的氢化反应,转化率高达约 58 000 h-1 或 129 000 h-1(按表面
钯原子校正)。此外,在 β-
月桂烯的氢化过程中,这种纳米催化剂对形成单氢化化合物具有高度选择性。与由支撑在
氨基改性磁性载体或 Pd/C 上的
钯纳米颗粒组成的类似纳米催化剂相比,该纳米催化剂的活性和选择性都有很大提高。这些结果表明,设计适当的混合
配体来对载体进行官能化,可以极大地影响
金属纳米颗粒的催化特性。