Graphitic carbon-wrapped iron nanoparticles derived from a melamine-modified metal-organic framework as efficient Friedel-Crafts acylation catalysts

Developing efficient heterogeneous catalysts for Friedel-Crafts acylation (FCA) reactions is highly attractive for its wide application in green synthesis and biomass conversion. Herein, a series of graphitic carbon-wrapped iron nanoparticles (Fe/C-x, x refers to the heat temperature ranged from 500 to 800 °C) were prepared through pyrolysis of a metal-organic framework (MOF) precursor of Fe-TPA-Mel, synthesized from iron salt, terephthalic acid (TPA) and melamine (Mel). The resultant Fe/C-600 catalyst exhibited excellent catalytic activity for the acylation of aromatic compounds with acyl chlorides, and better recyclability than the reference catalyst of Fe/C-600-ref derived from the Fe-TPA precursor. Various characterization results demonstrated that introducing melamine in the MOF precursor is beneficial for the formation of graphitic carbon-wrapped Fe nanoparticles at relatively low pyrolysis temperature, although the N species existed in the precursor of Fe-TPA-Mel could be nearly completed removed during the pyrolysis process. The relatively uniform graphitic carbon shell could provide an effective protection for the inside active iron species, finally resulting in the generation of stable and easily recycled heterogeneous FCA catalysts.