Higher alcohol synthesis (HAS) from syngas using highly
active
CoCu catalysts has attracted extensive interest, but there still exist
problems such as the low coordination between Co and Cu phases and
poor catalytic stability. Here, a series of highly dispersed bimetallic
CoCu catalysts with different Co/Cu ratios (x = 1–4)
encapsulated in KIT-6 were proposed and showed high performances in
HAS. The best is Co3Cu1/KIT-6 with a space-time
yield toward C2+OH of 31.9 mmol gcat
–1 h–1 and excellent stability over 200 h. Notably,
these catalysts had well-dispersed metal particles and abundant CoCu
alloy sites that were maintained during the reaction, which was benefited
from the preparation method of ethylene glycol (EG)-assisted impregnation
combined with stepwise pyrolysis. The EG-derived glyoxylate dianion
could effectively anchor Co and Cu species in the same precursor,
enabling them in atomic close interaction, which also favored their
synergistic catalysis in HAS. In addition, the stepwise pyrolysis
and the confinement of KIT-6 promoted the high dispersion of CoCu
species, facilitating the catalytic activity. Meanwhile, the maintenance
of highly dispersed and atomic close interacted CoCu bimetallic sites
ensured good stability of the catalyst for HAS. These results may
provide new ideas for the design and fabrication of high-performance
HAS catalysts.
Higher alcohol synthesis (HAS) direct from syngas using Febased catalysts is quite promising, but there are still problems in the construction of intimate-contact and stable dual sites to obtain satisfactory higher alcohol selectivity and space time yield (STY). Herein, a series of Au−Fe 2.2 C catalysts derived from monodisperse Janus Au−Fe 3 O 4 nanoparticles with different Fe/Au ratios were prepared. The optimal catalyst with a Fe/Au molar ratio of 11.6 achieved the most Janus nanoparticles and exhibited the highest STY toward higher alcohols of 0.195 g g cat −1 h −1 and excellent catalytic stability over 200 h. The superior performance of this catalyst was attributed to the unique Au−Fe 2.2 C Janus structure, which could enhance both CO insertion and CO dissociation as well as their synergistic effect. The correlation of the CO adsorption behavior and STY toward alcohols was established as well, indicating that the balance between CO nondissociated adsorption and CO dissociated adsorption played an important role in enhancing the alcohol formation. Moreover, the strong interaction between Au and iron species in Janus nanoparticles could facilitate the formation of ε′-Fe 2.2 C and benefit the stability of the catalyst. These results may provide new ideas for the design and fabrication of high-performance catalysts with dual sites for HAS.
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