Steady-state isotopic transient kinetic analysis of the Fischer–Tropsch synthesis reaction over cobalt-based catalysts

• Published in: Chemical engineering science Vol. 56; no. 4; pp. 1211 - 1219
• Main Authors: van Dijk, H.A.J., Hoebink, J.H.B.J., Schouten, J.C.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2001; Elsevier
• Subjects: Alcohols; Applied sciences; Catalysis; Catalytic reactions; Chemistry; Energy; Exact sciences and technology; Fischer–Tropsch; Fuel processing. Carbochemistry and petrochemistry; Fuels; Gas processing; GCMS analysis; General and physical chemistry; Hydrocarbons; Mechanistic modeling; SSITKA; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Fischer–Tropsch; Hydrocarbons; Mechanistic modeling; GCMS analysis; SSITKA; Alcohols; Isotopic analysis; Isotope labelling; Hydrogen; Oxygen 18; Alcohol; Cobalt; Synthesis gas; Supported catalyst; Reaction mechanism; Carbon monoxide; Platinoid; Carbon 13; Transient response; Catalytic reaction; Ruthenium; Hydrocarbon; Coupled method; Reaction product; Fischer Tropsch synthesis; Transition metal; Experimental study; Transient method; Titanium Oxides; Heterogeneous catalysis; Gas chromatography; Fischer Tropsch catalyst; Kinetics; Mass spectrometry
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/S0009-2509(00)00342-0

The paper presents a transient kinetic analysis of the Fischer–Tropsch synthesis reaction using the SSITKA technique in combination with a gas-chromatograph-mass-spectrometer (GCMS) analysis of the 13C-labeled and 18O-labeled hydrocarbon and alcohol reaction products. Experiments are performed on a Co/Ru/TiO 2 catalyst and a fully metallic Co-sponge model catalyst at 498 K and 1.2 bar. The experimental results are discussed in a qualitative way to obtain mechanistic information. The Co-sponge catalyst is used to study alcohol formation, since the TiO 2 support disturbs the measurements on the Co/Ru/TiO 2 catalyst. The formation of hydrocarbons proceeds via a two-pool mechanism, where two carbon pools contribute to methane formation and C–C coupling. Paraffins and olefins are both primary products, but the GCMS analysis demonstrates that readsorption of 1-olefins is an important step. The readsorption of iso- and 2-olefins is shown to be of less importance. The steady-state performance of the catalyst indicates the presence of a physisorbed hydrocarbon layer, even under process conditions where no wax build-up in the catalyst pores occurs. Although the Anderson–Schulz–Flory distribution gives rise to assume chain-length independence of the surface reactions starting at C 3, this does not hold when discrimination between the paraffins and the olefins is made. Alcohol formation can be considered as a termination reaction that occurs via a CO insertion or a CH x O insertion mechanism.