Deutero-1-pentene tracer studies for iron and cobalt Fischer–Tropsch synthesis

The addition of D5-1-pentene[4,4,5,5,5] to the synthesis gas fed to cobalt and iron catalysts under Fischer–Tropsch synthesis conditions show that H/D exchange does not occur to a measurable extent. The added D5-1-pentene[4,4,5,5,5] underwent hydrogenation, isomerization to interval alkenes and initiated chain growth to a greater extent with the cobalt than the iron catalyst. The data show similar results for both catalysts with the readsorbed alkene initiating chain growth, but not in an amount to significantly impact the product distribution. For cobalt, but not for iron, the added alkene may also be involved in the hydroformylation reaction. The data clearly show that vapor pressure and product accumulation effects must be accounted for in mechanism studies using isotopic tracers. The added D5-1-pentene[4,4,5,5,5] was found to initiate a growing hydrocarbon chain as the CD3CD2CH2CH2CH2 unit without measurable scrambling of the isotope label in contrast to earlier work with deuterated ethanol using a cobalt catalysts.

Figure optionsDownload high-quality image (35 K)Download as PowerPoint slideResearch highlights▶ D5-1-pentene initiates chain growth without any H/D scrambling for both Fe and Co FT synthesis. ▶ Hydrogenation and isomerization of the added D5-1-pentene are dominating reactions. ▶ D5-labeled FT products show a characteristic lower chain growth probability.