Anderson-Schulz-Flory distribution model

The FTS mechanism could be considered a simple polymerization reaction, the monomer being a Ci species derived from carbon monoxide. This polymerization follows an Anderson-Schulz-Flory distribution of molecular weights. This distribution gives a linear plot of the logarithm of yield of product (in moles) versus carbon number. Under the assumptions of this model, the entire product distribution is determined by one parameter, a, the probability of the addition of a carbon atom to a chain (Figure 4-7). ... 

Krishna and Bell (299) described the results of their steady-state tracing experiments by the model shown in Fig. 31. The scheme is in accord with the Anderson-Schulz-Flory distribution of products, based on chain growth by the successive addition of monomers s to chain fragments C s- is different from Ci,s. ft is assumed that the probability of chain growth a is not a function of n, where... 

Marano and Holder have calculated the VLE of the Fischer-Tropseh system. The pseudo-components were defined with the aid of an analytical molar-mass distribution function (Anderson-Schulz-Flory distribution). The properties of a pseudo-component were based on a hypothetical model component in each carbon-number cut. 

Product distributions can be evaluated for reaction probabilities of elemental surface reaction steps with the model of non trivial surface polymerisation [2]. Specific inhibition of desorption of a chemisorbed organic species has been postulated to be the intrinsic principle of the FT-synthesis [5]. A chemisorbed species can react further by linear chain prolongation or chain branching or it can desorb as a paraffin, olefin or an organic oxygen compound. Growth probabilities pg, that contain a similar information as the Anderson-Schulz-Flory parameter a. 

Concurrent with FTS mechanism studies, product distribution models were developed based on the analysis of product composition. Friedel and Anderson28 29 in the 1950s published the Anderson-Schulz-Flory (ASF) distribution model to predict the wide range of products yielded from FTS. The equation is shown as follows ... 

Keywords Cobalt catalyst. Kinetics, Modeling, Fischer-Tropsch synthesis. Hydrocarbon Product Distribution, Anderson-Schulz-Flory. 

Figure 15.14 (a) Product distribution of the Fischer—Tropsch synthesis predicted by Anderson—Schulz—Flory (ASF) polymerization model, (b) Product distribution obtained in the Fischer—Tropsch synthesis with different catalysts. 

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