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

Abstract

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.

Janus Au–Fe2.2C Catalyst for Direct Conversion of Syngas to Higher Alcohols

“…It was found that the moderately adsorbed CO was predominant in monometallic Au, while the strongly adsorbed CO emerged and became dominant gradually with increasing Fe/Au molar ratio, indicating that CO bonding with FeC x was stronger than that with Au. According to the literature, the moderately adsorbed CO prefers nondissociation and direct insertion (denoted as CO non ), while the strongly adsorbed CO tends to dissociate (denoted as CO dis ) in the F–T reaction conditions . It suggested that Au sites are mainly responsible for CO nondissociative adsorption while FeC x sites are mainly responsible for CO dissociative adsorption.…”

“…Significant advancements have been achieved in developing high-performance catalysts for higher alcohol synthesis directly from syngas. Four types of catalysts have been proposed and applied in HAS, which are Rh-based catalysts, Mo-based catalysts, modified methanol synthesis catalysts, and modified Fischer–Tropsch (F–T) catalysts. − Among them, Cu-modified Fe-based catalysts have been extensively studied due to the low cost, abundant reserves, and prospects for converting biomass or coal-derived syngas which has a wide H 2 /CO ratio …”

In Situ Encapsulated CuCo@M-SiO2 for Higher Alcohol Synthesis from Biomass-Derived Syngas

“…The characteristic diffraction peaks assigned to the (100), (110), and (200) crystal planes are displayed in Figure S7, which illustrate that all samples retained the two-dimensional (2-D) hexagonal symmetry with the space group p 6 mm . For CuCo@M-SiO 2 -1,2, CuCo@M-SiO 2 -2, and CuCo@M-SiO 2 -1,4 catalyst, the characteristic peaks corresponding to (100) and (110) crystal planes shifted to a lower 2θ angle, implying that NPs were encapsulated in the mesoporous of M-SiO 2 …”

“…However, it is an enormous challenge to achieve a trade-off between the C–C coupling and the C–O retaining. Typically, four categories of catalysts including Rh-based, − Mo-based, − modified methanol-synthesized catalysts, − and modified Fischer–Tropsch (F–T)-synthesized catalysts have long been investigated for HAS. − Although Rh-based catalysts have high C 2+ OH selectivity with Rh 0 -/Rh n + -active centers, the industrialization was unrealistic because of limited reserves and exorbitant price. Harsh reaction conditions and strict H/C ratio with Mo-based catalysts is not conducive to the practical application in HAS.…”

Highly efficient TiO2-supported Co–Cu catalysts for conversion of glycerol to 1,2-propanediol

“…The TPR profile of 0.5Cu/TiO 2 had a reduction peak at 115 °C with a shoulder peak at 160 °C, corresponding to the reduction of Cu 2 O and CuO to Cu, respectively 29 . For the bimetallic catalysts, the TPR profile of 15Co0.5Cu/TiO 2 had an overlapped peak at a lower temperature (205 °C) involved with the reduction of Co 3 O 4 to CoO, CuO to Cu, and Cu x Co 3-x O 4 to Cu and Co 30 , and a relatively large broad reduction peak at higher temperature (approximately 280–500 °C), assigned to the reduction of CoO to Co 31 . Interestingly, 15Co1Cu/TiO 2 had an overlapped reduction peak around 100–250 °C with a relatively small broad peak around 250–300 °C.…”