中国科学院大学化学学院刘伟研究团队取得一项新突破。他们揭示了夹心催化剂中辅助Co-N4单位点铂纳米粒子对卤硝基苯的化学选择性加氢反应。2025年3月27日，国际知名学术期刊《美国化学会杂志》发表了这一成果。

在这项研究中，研究组将Pt纳米颗粒（NPs）与卟啉金属有机框架[称为PCN-221(Co)]中的辅助性Co–N4单位点整合在一个夹层纳米结构中，作为催化剂，在50mL间歇微反应器中，在80°C和1 MPa H₂下对邻卤硝基苯进行化学选择性加氢。在邻氯硝基苯几乎完全转化的情况下，这种夹在中间的催化剂对邻氯苯胺的选择性达到97.3%，具有11,625 h^-1的极高周转频率（TOF），并且在10个循环中具有良好的再热性，优于目前最先进的异相支撑的金属催化剂。理论和实验研究表明，邻氯硝基苯中的硝基被Pt NPs优先加氢，而邻氯基被PCN-221（Co）中的Co–N4单位点选择性吸附，阻止了邻氯苯胺的氢解，增强了邻氯苯胺的选择性。

此外，夹心催化剂中的PCN-221（Co）壳层在富集邻氯硝基苯和稳定负载Pt NPs方面发挥了关键作用，使其具有较高的催化活性和良好的再热性。此外，在邻氟硝基苯和邻溴硝基苯几乎完全转化时，该夹层Pt催化剂对邻氟苯胺的选择性为100%，TOF为8680 h^-1，对邻溴苯胺的选择性为99.2%，TOF为5859 h^-1。以间硝基苯和对硝基苯为底物时，夹在中间的Pt催化剂对相应的卤代苯胺也具有较高的活性和良好的选择性。

据悉，卤代硝基苯的化学选择性加氢制卤代苯胺具有重要意义，但要同时实现高催化活性、优异的选择性和良好的再热性仍然具有挑战性，特别是对邻取代底物。这是由于卤素基团发生氢解，以及在硝基加氢过程中活性物质在催化剂表面容易迁移和聚集。

附：英文原文

Title: Chemoselective Hydrogenation of Halonitrobenzenes by Platinum Nanoparticles with Auxiliary Co–N4 Single Sites in Sandwiched Catalysts

Author: Tian Lin, Zhouwen Cao, Junqi Pei, Bohua Wang, Hanlin Liu, Bin Tu, Caoyu Yang, Fengbin Zheng, Wenxing Chen, Qiaojun Fang, Wei Liu, Zhiyong Tang, Guodong Li

Issue&Volume: March 27, 2025

Abstract: The chemoselective hydrogenation of halonitrobenzenes to haloanilines is of great importance but remains challenging to simultaneously achieve high catalytic activity, excellent selectivity, and good reusability, especially for ortho-substituted substrates. This is due to the occurrence of hydrogenolysis of halogen groups, as well as the easy migration and aggregation of active species on the catalyst surface during the hydrogenation of nitro groups. In this study, we integrate Pt nanoparticles (NPs) with auxiliary Co–N4 single sites from a porphyrinic metal–organic framework [known as PCN-221(Co)] in a sandwiched nanostructure as a catalyst for the chemoselective hydrogenation of ortho-halonitrobenzenes at 80 °C and 1 MPa H2 in a 50 mL batch microreactor. This sandwiched catalyst achieves 97.3% selectivity for ortho-chloroaniline at nearly complete conversion of ortho-chloronitrobenzene, with an exceptionally high turnover frequency (TOF) of 11,625 h–1 and good reusability over ten cycles, outperforming state-of-the-art heterogeneous supported metal catalysts. Theoretical and experimental investigations reveal that the nitro group in ortho-chloronitrobenzene is preferentially hydrogenated by Pt NPs, while the ortho-chloro group is selectively adsorbed by Co–N4 single sites in PCN-221(Co), preventing its hydrogenolysis and enhancing selectivity for ortho-chloroaniline. Furthermore, the PCN-221(Co) shell in the sandwiched catalyst plays a key role in enriching ortho-chloronitrobenzene and stabilizing the supported Pt NPs, thus leading to high catalytic activity and good reusability. Additionally, at nearly complete conversion of ortho-fluoronitrobenzene and ortho-bromonitrobenzene, this sandwiched Pt catalyst displays 100% selectivity for ortho-fluoroaniline with a TOF of 8680 h–1 and 99.2% selectivity for ortho-bromoaniline with a TOF of 5859 h–1, respectively. When meta- and para-halonitrobenzenes are used as substrates, high activity and excellent selectivity for the corresponding haloanilines are also achieved by the sandwiched Pt catalysts.

DOI: 10.1021/jacs.4c18288

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c18288