Anderson-Schultz-Flory distribution

This is the well-known Anderson-Flory-Schultz (ASF) distribution. Figure 5.4.4 shows how the Fischer-Tropsch product distribution depends on the chain-growth probability, a. 

When methanol synthesis catalyst, prepared from CuO, ZnO and CrOj, was mixed with HY zeolite, C2+ hydrocarbons were obtained in a good selectivity(Run 1)[2]. The same catalyst made into granule gave better results (Run 3). The selectivities to ethane, propane and butane were higher and that to methane was lower. No olefin was observed. The hydrocarbons distribution of typical Cu-Zn-Cr/HY is shown in Figure 1. This is a typical distribution of MTG reaction, and quite different from Schultz-Anderson-Flory law. 

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. 

Argonne National Laboratory, 137 aromatics, 477 Arrhenius equation, 60 ART. See advanced refining technologies ASF. See Anderson-Schultz-Flory distribution model ash... 

FTS produces a wide distribution of products. Conventional catalysts typically give an Anderson-Schultz-Flory distribution of products, hence they are generally non-selective for specific products. Therefore, the development of highly active and selective catalysts has been a key goal. 

---