Intrinsic kinetics of Fischer–Tropsch reactions over an industrial Co–Ru/γ-Al 2O 3 catalyst in slurry phase reactor

Abstract

The rate of Fischer–Tropsch synthesis over an industrial well-characterized Co–Ru/γ-Al 2O 3 catalyst was studied in a laboratory well mixed, continuous flow, slurry reactor under the conditions relevant to industrial operations as follows: temperature of 200–240 °C, pressure of 20–35 bar, H 2/CO feed ratio of 1.0–2.5, gas hourly space velocity of 500–1500 N cm 3 g cat − 1 h − 1 and conversions of 10–84% of carbon monoxide and 13–89% of hydrogen. The ranges of partial pressures of CO and H 2 have been chosen as 5–15 and 10–25 bar respectively. Five kinetic models are considered: one empirical power law model and four variations of the Langmuir–Hinshelwood–Hougen–Watson representation. All models considered incorporate a strong inhibition due to CO adsorption. The data of this study are fitted fairly well by a simple LHHW form − R H 2 + CO = ap H2 0.988 p CO 0.508 / (1 + bp CO 0.508) 2 in comparison to fits of the same data by several other representative LHHW rate forms proposed in other works. The apparent activation energy was 94–103 kJ/mol. Kinetic parameters are determined using the genetic algorithm approach (GA), followed by the Levenberg–Marquardt (LM) method to make refined optimization, and are validated by means of statistical analysis. Also, the performance of the catalyst for Fischer–Tropsch synthesis and the hydrocarbon product distributions were investigated under different reaction conditions.