Highly chemoselective synthesis of imine over Co/Zn bimetallic MOFs derived Co3ZnC-ZnO embed in carbon nanosheet catalyst

• DOI: 10.1016/j.jcat.2021.07.005
• Publication Date: 2021-07-15T05:06:48Z
• Authors: Wei She; Jing Wang; Xuewei Li; Jingfang Li; Guijie Mao; Weizuo Li; Guangming Li
• Keywords: Nanosheet; Bimetallic strip; Nitrobenzene; Reductive amination

Abstract One-pot direct synthesis of imines via reductive amination of nitroarenes with aromatic aldehydes remains a great challenge due in part to its over-hydrogenation of imines to secondary amines. Herein, a novel Co3ZnC and ZnO supported on N-doped carbon nanosheet catalyst with the thickness of ca. 5.0 nm was fabricated through the direct pyrolysis of a Co/Zn bimetallic MOFs at 500 °C (named as Co3ZnC-ZnO/NC-500). Surprisingly, the developed Co3ZnC-ZnO/NC-500 catalyst delivers 99.9 % conversion of nitrobenzene and 98.5 % selectivity to N-benzylideneaniline in one-pot reductive amination of nitrobenzene with benzaldehyde. Various characterizations (including as SEM, XRD, TEM, AFM, XPS, Raman and N2 adsorption–desorption) have revealed that the generated small size of Co3ZnC alloy, abundant structural defects, larger specific surface area (105.5 m2·g−1) as well as more basic sites are responsible for the outstanding catalytic activity of Co3ZnC-ZnO/NC-500 catalyst for tandem reaction. Moreover, the Co3ZnC-ZnO/NC-500 catalyst exhibits high stability during the recycling experiments without the loss of its catalytic activity. Notably, the results of contrast experiments have demonstrated that the intentional introduction of ZnO in Co3ZnC-ZnO/NC-500 catalyst plays a key role in the selectivity to N-benzylideneaniline in the tandem reaction. This study provides a new guideline for designing tandem catalysts with high selectivity.