Analysis and prediction of product distributions of the Fischer-Tropsch synthesis

Abstract

A method is developed for calculating the three parameters needed to characterize the carbon number distribution of products of the Fischer-Tropsch synthesis. Experimental data are fit by a modified Schulz-Flory model that has two chain growth probabilities, using nonlinear regression. Excellent fit is shown for data from precipitated iron and fused magnetite catalysts. The model is used to calculate selectivity information of interest in catalyst comparison and reactor design. Advantages of this method over asymptotic regression methods are discussed in detail.

The product distribution in Fischer–Tropsch synthesis: An extension of the ASF model to describe common deviations

“…for C 10+ components (see Figure 5). Such a deviation can be found especially for iron catalysts (Donnelly et al, 1988;Patzlaff et al, 1999;Egiebor et al 1986;van der Laan and Beenackers, 1999), but also on cobalt or ruthenium catalysts (Iglesia et al, 1991;van der Laan and Beenackers, 1999) with additional deviations in C 1 and C 2 (see Figure 8).…”

“…Depending on the interpretation of this behavior, different modelling approaches have used. Madon and Taylor (1981) interpreted this deviation by assuming two different chain growth probabilities caused by different types of catalytic sites, which is then modelled by superposition of two (independent) ideal ASF distributions and thus called 'double-ASF distribution (Donnelly et al, 1988). Also different chain termination reactions were proposed as potential explanation (Wojciechowski, 1988;Sarup and Wojciechowski, 1988).…”

“…It is based on the superposition of two independent ASF distributions and has shown to be a useful method to describe a wider range of experimentally observed distributions (e.g. Donnelly et al, 1988;Patzlaff et al, 1999).…”

A comprehensive mathematical model for the Fischer–Tropsch synthesis in well-mixed slurry reactors

“…The resulting model is an implementation of the two superimposed ASF distribution model of Patzlaff et al (1999) and Donnelly et al (1988). In this case, Eqs.…”

“…Regarding the selectivity modeling, two effects are usually pointed out as the causes for non-ASF product distributions in FT synthesis: 1-olefin readsorption with secondary chain propagation (Iglesia et al, 1991;Van der Laan and Beenackers, 1999;Schulz and Claeys, 1999) and the existence of two chain propagation mechanisms or sites (Madon and Taylor, 1981;Sarup and Wojciechowski, 1988;Donnelly et al, 1988;Patzlaff et al, 1999Patzlaff et al, , 2002. Although 1-olefin readsorption with secondary chain propagation is regarded as the correct explanation of non-ASF product distributions for ruthenium catalysts (Iglesia et al, 1991;Patzlaff et al, 1999), the existence of two different mechanisms or active sites for chain propagation seems to be the major effect for iron and cobalt catalysts (Patzlaff et al, 1999(Patzlaff et al, , 2002.…”