High-Performance CoCu Catalyst Encapsulated in KIT-6 for Higher Alcohol Synthesis from Syngas

摘要

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 g(cat)(-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.