MOFs carbonization: In-situ encapsulation of Co-species into N-doped carbons as highly efficient catalysts for nitrobenzene hydrogenation

N-doped carbons were amazing supports for metal particles to produce fine chemicals in heterogeneous catalysis. Here, N-doped carbons supported Co-species were obtained by in-situ ZIF-67 pyrolysis at 900 degrees C, where the ratio of ligands was changed to modulate particle size and coordination of Co-source. Co-NC-8 sample from eight-fold ligands to Co-source preserved the shape of ZIF-67 with higher content of N-species especially for graphitic-N, exhibiting superior performance in nitrobenzene hydrogenation to aniline, and the conversion of 100% and aniline selectivity of 99% reached at 120 degrees C and 1 MPa H-2 after 3 h reaction. The conversion was still up to 80% even as catalysts recycled for seven times, and the dispersed Co-species in carbons made easily magnetic separation. Besides, Co-NC-8 also showed considerable activity for other nitro compounds to form amine. The efficient catalytic performance of Co-NC-8 was related to synergistic effects of Co and N-species as active centers, as well as partial mesopores and macropores as diffusion channels. This research offered a facile approach to modulate particle size and coordination of Co-species in carbons, serving as efficient catalysts for various catalytic applications.

Automated summary

This study obtained N-doped carbon supported Co-species by in-situ ZIF-67 pyrolysis at 900 degrees C, and the ratio of ligands was changed to modulate particle size and coordination of Co-source. The obtained Co-NC-8 sample showed superior performance in nitrobenzene hydrogenation to aniline, with high conversion and selectivity, as well as easy magnetic separation due to dispersed Co-species in carbons.