Unravelling Molecular Composition of Products from Cobalt Catalysed Fischer-Tropsch Reaction by Comprehensive Gas Chromatography: Methodology and Application

New analytical approaches combining different types of gas chromatography techniques such as low resolution, high resolution and two-dimensional gas chromatography were carried out to provide enhanced molecular characterization of Fischer-Tropsch (FT) products. In particular, a detailed composition of olefin and oxygenates by-products was achieved thanks to magnified resolution associated with the high peak capacity provided by GC x GC. Such a detailed description of the whole FT products distribution brings additional information which improve the Fischer-Tropsch reaction knowledge. Thus, we have shown that all the three products family (paraffin, olefin and oxygenates) present their own Anderson Schulz Flory (ASF) distribution. Apart from methane and ethylene which present their own particularity, the Fischer-Tropsch selectivity can be described by three chain growth coefficients relative to each products family. These results allow new understanding of the reaction mechanism. An hypothesis is proposed.