ON INTERPRETING FT PRODUCT DISTRIBUTION DATA

It is shown that a CSTR is essential for the correct evaluation of kinetic parameters in the Fischer-Tropsch (FT) synthesis. Furthermore, a rather complicated expression is required in order to extract the correct growth probability at low carbon number in cases where a 'break' is observed in the Anderson-Schulz-Flory (ASF) distribution. It is shown that if product molecules can readsorb and continue to grow on a variety of locations where competing processes occur, the linearities of the ASF plot are preserved but the slopes of the plot no longer have a simple interpretation in terms of processes governing chain growth on the surface. Finally, results obtained using an integral Plug Flow Reactor (PFR) are shown to yield 'growth probabilities' which have no fundamental significance and are a function of the level of conversion and of the input H//2/CO ratio.