Calculating the product yields and the vapor–liquid equilibrium in the low-temperature Fischer–Tropsch synthesis

The ultimate goal of this paper is the assessment of the yield of liquid hydrocarbons formed in the low-temperature Fischer–Tropsch synthesis over a representative cobalt-based catalyst at relevant process conditions. To achieve this goal, a set of steady-state Fischer–Tropsch runs has been carried out in a lab-scale reactor loaded with a 20 wt.% Co/Al2O3 catalyst, investigating the effects of the main process conditions (temperature, H2/CO inlet ratio, content of inert gas in the feed, syngas space velocity) on the reactants conversion and on the C1–C50 product selectivity. Then, a CO conversion kinetic model and a product distribution model have been developed and have been jointly adopted to describe the product yields in the reactor as a function of the process conditions. Product yields have been finally used as input for an isothermal and isobaric non-ideal vapor–liquid equilibrium calculation. It has been found that, at the typical low-temperature Fischer–Tropsch synthesis process conditions, more than 95 mol.% of the C1–C30 hydrocarbons, that in general represent more than 99 mol.% of the hydrocarbon products, are in the vapor phase.

Graphical abstract.Figure optionsDownload full-size imageDownload high-quality image (88 K)Download as PowerPoint slideHighlights► CO conversion kinetics and product distribution model have been developed. ► Non-ideal VLE based on Peng–Robinson EOS has been used. ► Developed model predicts the yields of vapor and liquid hydrocarbons. ► At the typical conditions, more than 95 mol.% of the C1–C30HCs is vaporized. ► The presence of a liquid in the reactor may strongly affect the FTS performances.