Tuning interaction between cobalt catalysts and nitrogen dopants in carbon nanospheres to promote Fischer-Tropsch synthesis

Abstract

N-doped carbon supports are promising to improve reduction degree and dispersion of metal catalysts in Fischer-Tropsch synthesis (FTS). However, it is a great challenge to reasonably construct desired N dopants on FTS catalysts. Herein, we report the high FTS performance of the Co catalysts supported on N-doped carbon nanospheres synthesized by using a facile strategy. Through precisely tailoring the N dopants, we discover that the interaction between cobalt catalysts and supports is significantly strengthened via donation electron function of N atoms, especially for pyrrolic N. It improves the dispersion of cobalt species to generate more electron-enriched cobalt sites, which can strongly adsorb CO and accelerate CO dissociation to C*, resulting in the enhanced catalytic activity. In addition, these in turn increase C* concentration on the surface of the active cobalt sites, which is favorable to form a high concentration of chain initiators CH2 to stimulate carbon-chain growth, inducing the high selectivity towards the C5+ products in FTS. Accordingly, the Co/NCS-500 catalyst with the high content of pyrrolic N presents the high FTS activity and C5+ selectivity. Our work provides a new avenue in rational development of other related heterogeneous catalysis.