Iron-based nanoparticles embedded in a graphitic layer of carbon architectures as stable heterogeneous Friedel-Crafts acylation catalysts

A series of carbon supported iron nanoparticle composites were prepared by pyrolysis of two kinds of Fe-MOF materials, Fe-diamine-dicarboxylic acid and Fe-dicarboxylic acid, and were characterized by a variety of characterization techniques. The composites pyrolyzed at higher temperatures are composed of iron-based nanoparticles (Fe3C) and porous carbon architectures with graphitic characteristics. The catalytic properties of these composites were investigated for the Friedel-Crafts acylation of aromatic compounds with acyl chlorides. Among them, Fe@NC-800, derived from the pyrolysis of Fe-diamine-dicarboxylic acid at 800 degrees C, exhibited excellent catalytic activity and stability for the acylation reactions, and could be easily recycled several times without an obvious loss in activity. The excellent catalytic performance of Fe@NC-800 should be mainly attributed to the microstructural characteristics of the active sites, in which most of the small iron-based nanoparticles are encapsulated in the graphitic layer of the carbon architecture, thus providing a suitable geometric environment for stabilizing iron species. Besides, the electronic effects exerted by the graphitic layer of porous carbon may also play a positive role in improving the catalytic activity and stability of the carbon supported iron-based catalyst for Friedel-Crafts acylation reactions.