State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin, 130012, P. R. China.
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin, 130012, P. R. China.
Adv Mater. 2023 Mar;35(11):e2209635. doi: 10.1002/adma.202209635. Epub 2023 Jan 11.
Supported metal catalysts have played an important role in optimizing selective semihydrogenation of alkynes for fine chemicals. There into, nitrogen-doped carbons, as a type of promising support materials, have attracted extensive attentions. However, due to the general phenomenon of random doping for nitrogen species in the support, it is still atremendous challenge to finely identify which nitrogen configuration dominates the catalytic property of alkynes' semihydrogenation. Herein, it is reported that uniform mesoporous N-doped carbon spheres derived from mesoporous polypyrrole spheres are used as supports to immobilized subnanometric Pd clusters, which provide a particular platform to research the influence of nitrogen configurations on the alkynes' semihydrogenation. Comprehensive experimental results and density functional theory calculation indicate that pyridinic nitrogen configuration dominates the catalytic behavior of Pd clusters. The high contents of pyridinic nitrogen sites offer abundant coordination sites, which greatly reduces the energy barrier of the rate-determining reaction step and makes Pd clusters own high catalytic activity. The electron effect between pyridinic nitrogen sites and Pd clusters makes the reaction highly selective. Additionally, the good mesostructures also promote the fast transport of substrate. Based on the above, catalyst Pd@PPy-600 exhibits high catalytic activity (99%) and selectivity (96%) for phenylacetylene (C H ) semihydrogenation.
负载型金属催化剂在优化炔烃的选择性半氢化反应以制备精细化学品方面发挥了重要作用。其中，氮掺杂碳作为一种很有前途的载体材料，引起了广泛关注。然而，由于载体中氮物种的掺杂通常是随机的，因此精细地确定哪种氮构型主导炔烃半氢化反应的催化性能仍然是一个巨大的挑战。在此，据报道，由介孔聚吡咯球衍生而来的均匀介孔 N 掺杂碳球被用作固定亚纳米 Pd 簇的载体，这为研究氮构型对炔烃半氢化反应的影响提供了一个独特的平台。综合实验结果和密度泛函理论计算表明，吡啶氮构型主导 Pd 簇的催化行为。高含量的吡啶氮位提供了丰富的配位位，极大地降低了速率决定步骤的能量势垒，使 Pd 簇具有高催化活性。吡啶氮位与 Pd 簇之间的电子效应使反应具有高选择性。此外，良好的介孔结构也促进了底物的快速传输。基于上述原因，催化剂 Pd@PPy-600 对苯乙炔（C6H5C≡CH）半氢化反应表现出高的催化活性（99%）和选择性（96%）。
