Tuning direct CO hydrogenation reaction over Fe-Mn bimetallic catalysts toward light olefins: Effects of Mn promotion

• Published in: Applied catalysis. B, Environmental Vol. 285; p. 119815
• Main Authors: Yang, Zixu, Zhang, Zhengpai, Liu, Yitao, Ding, Xiaoxu, Zhang, Jun, Xu, Jing, Han, Yifan
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-05-2021; Elsevier BV
• Subjects: Alkenes; Bimetals; Carbon monoxide; Carburization (corrosion); Carburizing; Catalysts; Catalytic activity; Fe-Mn bimetallic catalysts; Fischer-Tropsch synthesis; Hydrogenation; Light effects; Light olefins; Low temperature; Manganese; Morphology; Nanocrystals; Nanoparticles; Selectivity; Strong interactions (field theory); Structure transformation; Surface energy; Surface properties; Syngas; Synthesis gas; Volcanoes; Fischer-Tropsch synthesis; Light olefins; Fe-Mn bimetallic catalysts; Structure transformation; Syngas
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119815

[Display omitted]
•Mn incorporates into the lattice of Fe2O3 and decreases the crystallinity.•Mn decreases the surface energy of the nanocrystals and weakens the agglomeration.•Mn suppresses the reduction of Fe(II) to Fe(0).•Mn enhances CO dissociation and suppresses secondary hydrogenation of olefins.•The ratio of Fe5C2/Fe2C can be modulated by adjusting Mn content.
Highly dispersed FeMn bimetallic nanoparticles prepared by a low-temperature co-precipitation method were employed for direct CO hydrogenation for light olefins (C2∼C4=). An outstanding selectivity (60.6 %) for light olefins at a CO conversion level of 7.6 % was obtained over FeMn (4:1) catalyst activated by syngas (5%CO/5%H2). Characterization indicated that a strong interaction between Fe and Mn resulted in significant effects on stabilization of Fe1-xMnxO phase during activation period. Responding to the morphology effect, Mn decreased the surface energy of nanocrystals and weakened the agglomeration of nanoparticles, thus resulted in a decrease in particle size of Mn-promoted catalysts. The combined effects of inhibited carburization and improved metal dispersion contributed to the volcano pattern in the catalytic activity of Mn-promoted catalysts. In addition, Mn may act as an effective electron donor to Fe, enhancing CO dissociative adsorption while inhibiting secondary hydrogenation of olefins, thus giving rise to high olefin selectivity in CO hydrogenation.