N-Doped Porous Carbon–Fe_xC Nanoparticle Composites as Catalysts for Friedel–Crafts Acylation

Designing highly efficient heterogeneous catalysts for the Friedel–Crafts acylation (FCA) reaction is a very significant subject for the development of green chemical industry. Herein, a series of nanosized iron carbide-encapsulated N-doped porous carbons (FexC/NC-n) have been prepared through high-temperature pyrolysis of the Fe-Zn bimetallic organic framework for the catalytic application in FCA of aromatic compounds with acyl chlorides. A variety of characterization results demonstrated that the nanosized iron carbides (FexC), which are wrapped inside of the graphitic carbon shell, are the main active sites for the FCA reaction. Changing the ratios of Fe/Zn can considerably influence the particle size of FexC and the thickness of the graphitic carbon shell. The composition-optimized catalyst, named as FexC/NC-0.05, exhibited the highest activity and excellent recyclability for the reaction. The relatively thin graphitic carbon shell allows rapid penetration of reagents and, meanwhile, can also provide effective protection for the active FexC particles against leaching by space confinement and electronic effects, thus resulting in the formation of highly active and stable FexC/NC-n catalysts for the FCA reaction.