Diffusion and Reaction of the Products

In the F-T synthesis, 1-alkenes are produced as the primary products and are subjected to various secondary reactions such as hydrogenation, C-C chain propagation and hydrocracking [23,24]. 

Although the mass transfer rate in the supercritical fluid is lower than that in the gas phase, the alkene content in the hydrocarbons produced in supercritical 

Bukur et al. conducted the F-T reaction on an iron-based catalyst with supercritical phase propane [25-27], and similar conclusions were obtained, indicating the above analysis to be independent of the catalyst itself and the SCF. 

It is difficult to selectively synthesize waxy hydrocarbons through an F-T reaction. The main reason is that the F-T products follow the Anderson-Schultz-Flory (ASF) distribution [23,24]. Development of a new type of F-T reaction, free from ASF constraints on product selectivity, is of great importance for wax production, as modifrcation of the F-T catalyst alone is not enough to increase wax selectivity significantly. 

Addition of a small amount of heavy 1-alkene into supercritical phase F-T reaction can significantly promote the chain growth and greatly enhance the selectivity of waxy products. As a matter of interest, this phenomenon does not occur in the gas phase reaction [28-30]. 

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