Carbon-Carbon bond formation during Fe catalyzed Fischer-Tropsch synthesis

• Published in: Applied catalysis. A, General General, 2020-07, Vol.602, p.117607, Article 117607
• Main Authors: Shi, Buchang, Liao, Yunxin, Callihan, Zachary J., Shoopman, Brad T., Luo, Mingsheng
• Format: Article
• Language: English
• Subjects: Alkylidene; Alkylidene mechanism; Bonding; Carbon; Chemical reactions; Chemical synthesis; Deuterium; Deuterium enrichment; Deuterium tracer; Enrichment; Fischer-Tropsch process; Fischer-Tropsch synthesis; Hydrocarbons; Inverse isotope effect; Isotope effect
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2020.117607

[Display omitted] •There is an inverse isotope effect during iron catalyzed Fischer-Tropsch reactions.•Deuterium enrichment in hydrocarbons was observed in iron catalyzed Fischer-Tropsch reactions.•Deuterium enrichment is a function of carbon number.•Alkylidene mechanism for Fischer-Tropsch synthesis can explain the inverse isotope effect.•Detained calculations based on the alkylidene mechanism predict the deuterium enrichment. An inverse isotope effect and deuterium enrichments in hydrocarbons were observed in Fe catalyzed Fischer-Tropsch (FT) reactions. These results are explained by an Alkylidene mechanism by which the monomer of the polymerization-like reaction is MCH and the growing chain is RCH = M. The formation of CC bond is through the reaction of MCH and RCH = M, producing a new growing chain RCH2CH = M. During the process of CC bond formation, the sp2 carbon in RCH = M is changed to sp3 in newly formed growing chain RCH2CH = M, which results in an inverse isotope effect. The rate of reaction of RCD = M with MCH/M≡CD is fast than that of RCH = M with MCH/M≡CD. The calculations based on alkylidene mechanism showed that the deuterium is enriched in hydrocarbons and that the deuterium enrichment is a function of carbon number.