Nitrogen-doped mesoporous carbon supported FeCu bimetallic catalyst and its CO hydrogenation performance

In this work, nitrogen-doped mesoporous carbon (NDMC) was prepared by a hard template method, and the NDMC supported FeCu bimetallic catalysts were prepared by an impregnation method. The physical and chemical properties and CO hydrogenation performance of the catalysts with varying Fe/Cu ratios were studied. The results indicated that Cu-N had strong interaction which directly promoted Cu dispersion on the support. At a relatively high metal loading (45.0%-50.0%), Cu maintained uniform distribution similar to that of N, and the ratios of Fe/Cu on the catalyst surface were smaller than those in the bulk phase, which were different from precipitated Fe-Cu bimetallic catalysts. The XPS results showed that Cu was an electron donor, and the electrons in the Cu-N shifted to Fe. Compared with Fe/NDMC, the reduction of Fe_xCu_y/NDMC was facilitated, and their CO hydrogenation activity was significantly increased. Under the pretreatment conditions (H₂, 300℃), Fe was not completely reduced, and H might mainly interact with Fe-O in the form of Fe-O-H, while Cu-N interaction was stronger than Cu-H, resulting in a decrease in the ratio of surface active carbon/hydrogen, leading to a gradual increase in C₅₊ selectivity with the decrease of Fe/Cu ratio. Meanwhile, the introduction of Cu inhibited CO dissociation to some extent, and the electron migration ability of the support to the metal gradually increased with decreasing Fe/Cu ratio, and as a result the surface alkalinity of the catalysts increased with increasing Cu content, leading to further enhancement of C₅₊ selectivity and alcohol selectivity.