MOF-derived Ni@NC catalyst: synthesis, characterization, and application in one-pot hydrogenation and reductive amination

Abstract

MOF-derived catalysts with nickel nanoparticles (NPs) uniformly embedded in nitrogen doped carbon shells were developed by pyrolysis of nickel-based metal–organic frameworks (MOFs), in which amino groups were introduced to act as the nitrogen source and possible anchoring sites for Ni NPs. The resulting materials were characterized systematically. In the architecture of the catalysts, a core–shell structure was discovered, in which Ni NPs with a diameter of 6–7 nm were surrounded by N doped graphitic layers, indicating that the introduction of amino groups into precursors is beneficial to the dispersion of NPs. One-step hydrogenation and reductive amination (OHRA) is a promising route to produce secondary amines, which avoids tedious separation of intermediates. Accordingly, we applied the prepared composites as catalysts to OHRA of benzaldehyde with nitrobenzene. Among them, the catalyst pyrolyzed at 600 °C for 1.5 h exhibited the best catalytic performance (conversion: >99%, selectivity for N-benzylaniline: 97.96%) and excellent recyclability. N-doping remarkably promotes the dispersion and stability of Ni NPs, thus improving their catalytic activity and selectivity. Furthermore, the Ni–N species as well as synergism of Ni NPs and adjacent pyridinic N may also facilitate the activation of H₂. And its excellent stability and recyclability can be attributed to the core–shell structure. The achieved success in MOF-derived nanocomposites may pave the way for further industrial applications.