Variation of residence time with chain length for products in a slurry-phase Fischer–Tropsch reactor

Abstract

The phrases “product accumulation” or “accumulated products” or “product holdup” have appeared in literature during the past several decades to qualitatively explain the experimental results for Fischer–Tropsch synthesis (FTS). This study develops an experimental method for a slurry reactor to evaluate the product accumulation inside the FT reactor by measuring the average residence time of products as a function of carbon number. The effect of accumulation of products on vapor–liquid equilibrium (VLE) in the reactor is also investigated. The results show that VLE is reached inside the FT reactor for components up to C17. Furthermore, the relationship between the mole fractions of components in the vapor and the liquid phase for lighter hydrocarbons, up to around C17, is adequately described by Raoult’s law. These results suggests that chain length–dependent solubility in the liquid phase is the predominant cause for chain length dependencies of secondary olefin reactions in FTS, and diffusion-limited removal of products is only significant for products with carbon number greater than 17.