Deuterium tracer studies on cobalt catalyzed Fischer–Tropsch synthesis: Addition of alcohols

Unlike the iron catalyzed Fischer–Tropsch (FT) synthesis, the additions of ethanol-d6 and 2-propanol-d8 during the Co/SiO2 catalyzed FT reactions did not produce detectable amount of deuterated isomer in any alkane. However, when the FT reactions were conducted over a mixture of FT catalyst Co/SiO2 and dehydration catalyst Al2O3, the d1, d2 and d3 isomers of alkanes from C7 to C15 were obtained with a nearly constant D/molecule value of 1.4 when ethanol-d6 was used as the tracer while d1–d6 isotopic isomers of alkanes were observed with a nearly constant D/molecule value of 2.3 when 2-propanol-d8 was used. The similar results were obtained when 1-propanol was used as the tracer. These results lead us to conclude that the C2 or C3 species that initiates the chain growth in the FT reaction resembles ethene or propene. The pathways for the formations of ethylidene and propylidene were proposed.

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► Alcohols cannot initiate the chain growth during Co/SiO2 catalyzed FT reaction.
► Alcohols were incorporated into alkanes when the FT reactions were conducted over Co/SiO2 + Al2O3.
► Nearly constant D/molecule (H/molecule) values were obtained.
► The pathways for the formation of ethylidene and propylidene were proposed.