Influence of the metal sites of M-N-C (M = Co, Fe, Mn) catalysts derived from metalloporphyrins in ethylbenzene oxidation

Transition metal catalysts M-N-C (M = Co, Fe, Mn) were synthesized by a template-free method by heating meso-tetraphenyl porphyrins (i.e. CoTPP, FeTPPCl, MnTPPCl) precursors. The catalysts were characterized by N2 adsorption-desorption, thermogravimetry, high-resolution transmission electron microscopy, and Raman and X-ray photoelectron spectroscopy. The selective oxidation of ethylbenzene with molecular oxygen under a solvent-free condition was carried out to explore the catalytic performance of the M-N-Cs, which exhibited different catalytic performance. That was ascribed to the difference in M (Co, Fe, Mn) and different graphitization degree forming during the heating process, in which M (Co, Fe, Mn) might have different catalytic activity on the formation of the M-N-C catalyst. All the M-N-C composites had remarkable recyclability in the selective oxidation of ethylbenzene.

Graphical AbstractM-N-C (M = Co, Fe, Mn) catalysts synthesized by heating meso-tetraphenyl porphyrins (i.e. CoTPP, FeTPPCl, and MnTPPCl) have different calcination degree which was caused by the different catalytic activity of the metal sites during the heating of the metalloporphyrins.Figure optionsDownload as PowerPoint slide