Direct synthesis of long-chain alcohols from syngas over CoMn catalysts

Na-promoted CoMn catalyst is able to produce higher alcohols via syngas with C2+ and C6+ fractions account for >90wt% and ∼50wt%, respectively. [Display omitted] •Na-promoted CoMn catalyst is able to produce higher alcohols with high C2+ and C6+ fractions.•Significant structural evolution occurs...

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Bibliographic Details
Published in:Applied catalysis. A, General General, 2018, Vol.549, p.179-187
Main Authors: Yang, Yanzhang, Lin, Tiejun, Qi, Xingzhen, Yu, Fei, An, Yunlei, Li, Zhengjia, Dai, Yuanyuan, Zhong, Liangshu, Wang, Hui, Sun, Yuhan
Format: Article
Language:English
Subjects:
Active dual-sites
Alcohols
Aldehydes
Carbon dioxide
Carbonization
Catalysis
Catalysts
Chains
Co2C
Cobalt
Fischer-Tropsch
Higher alcohol synthesis
Nanoparticles
Selectivity
Syngas
Synthesis gas
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Summary:Na-promoted CoMn catalyst is able to produce higher alcohols via syngas with C2+ and C6+ fractions account for >90wt% and ∼50wt%, respectively. [Display omitted] •Na-promoted CoMn catalyst is able to produce higher alcohols with high C2+ and C6+ fractions.•Significant structural evolution occurs during reaction with formation of bulk Co2C and MnCO3.•Na plays a significant role in promotion of Co2C formation.•Co2C/Co and synergistic effect of certain facets of Co2C are suggested to be active sites for higher alcohol synthesis. CoMn model catalysts were prepared by co-precipitation and evaluated for higher alcohol synthesis (HAS) via syngas. The selectivity to oxygenates (mainly alcohols and aldehydes) was found to be higher than 20C% for the Na-promoted CoMn catalyst. Among the oxygenates, C2+ and C6+ fractions accounted for >90wt% and ∼50wt%, respectively. Metallic Co0 particles and MnCO3 were found in both Na-promoted and unpromoted CoMn catalysts after the reaction, whereas Co2C nanoparticles could only be observed in the spent Na-promoted catalyst. The addition of Na benefited the carbonization of cobalt and increased the selectivity to oxygenates and CO2. Our studies thus suggested that Co/Co2C were the bifunctional dual-sites for the oxygenates formation over the Na-promoted CoMn catalyst, where Co catalyzed CO dissociation and chain propagation, while Co2C was responsible for CO non-dissociative activation and subsequent insertion. In addition, the sole Co2C nanoparticles with certain exposed facets may also act as another kind of active dual-sites for oxygenates formation.
ISSN:0926-860X
1873-3875
DOI:10.1016/j.apcata.2017.09.037