Fischer-Tropsch Synthesis in Novel Monolith Loop Reactors
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Multifunctionality (MF-3)
Keywords: Fischer-Tropsch Synthesis, Catalyst, Two-Phase Flow
Robert Güttel, Ulrich Kunz, Thomas Turek*
Institute of Chemical Process Engineering, Clausthal University of Technology,
Leibnizstr. 17, 38678 Clausthal-Zellerfeld, Germany
*corresponding author
The Fischer-Tropsch synthesis (FTS) is a strongly exothermic, heterogeneously catalysed reaction to convert synthesis gas into hydrocarbons. Modern reactor technologies for this reaction on industrial scale comprise slurry bubble columns and fixed bed reactors [1]. An alternative to these reactors with conventional catalyst geometries could be reactors with structured catalysts like honeycomb shaped monoliths. These structured reactors combine the advantages of slurry and fixed bed reactors, such as short diffusion distances and plug-flow residence time behaviour and eliminate their typical drawbacks like necessity for catalyst separation and high pressure drop. Monolithic reactors also allow for the achievement of very high gas-liquid mass transfer coefficients especially in the preferred Taylor-Flow regime [2].
First experimental and theoretical investigations have shown the feasibility of using monolithic reactors for FTS. Kapteijn et al. carried out experiments in single-pass operation of synthesis gas [3]. Furthermore, simulations of monolith reactors in the Taylor-Flow regime showed comparable or even better performance as in industrial slurry bubble columns. Hilmen et al. performed experiments with external oil recirculation and single-pass for the gas phase in the film flow regime inside the capillaries [4]. As a result these authors found that with recirculation of the liquid phase the temperature in the reactor was much easier to control, while the overall rate was found to be slightly lower than using powder catalysts.
This work presents a laboratory reactor concept that allows for the first time the investigation of FTS in the desirable Taylor-flow regime. It consists of a combination of fixed-bed reactor for the honeycomb catalyst and well-mixed tank reactor. Gas und liquid flow through the monolith can be independently adjusted by means of a compressor and a pump. Due to the high velocities of gas and liquid the conversion per pass is low, which results in entirely isothermal operation of the monolith. The stirred-tank reactor can also be used for experiments with powder catalysts in the slurry phase. Thus different catalyst geometries can be directly compared in the same experimental installation. In the present paper, first results comparing monolithic and powder catalysts are presented. Similar productivities and product distributions were obtained with both catalysts.
[1] M. Dry, Catalysis Today 71 (2002) 227
[2] S. Roy, T. Bauer, M. Al-Dahhan, P. Lehner, T. Turek, AIChE J. 50 (2004) 2918
[3] F. Kapteijn, R.M. De Deugd, J.A. Moulijn, Catalysis Today 105 (2005) 350
[4] A.-M. Hilmen, E. Bergene, O.A. Lindvag, D. Schanke, S. Eri, A. Holmen, Catalysis Today 105 (2005) 357
Presented Thursday 20, 16:00 to 16:20, in session EPIC-1: Multifunctionality (MF-3).
