Isotopic tracer studies of Fischer-Tropsch Synthesis over Ru/TiO sub 2 catalysts

Technical Report · Wed Jan 01 04:00:00 EST 1992

DOI:https://doi.org/10.2172/5128268· OSTI ID:5128268

Krishna, K R

Fischer-Tropsch synthesis is a process in which CO and H{sub 2} react to give predominantly liquid hydrocarbons. The reaction can be considered a special type of polymerization in which the monomer is produced in situ, and chain growth occurs by a sequence of independently repeated additions of the monomer to the growing chain. A investigation has been conducted to study the CO hydrogenation reaction in order to better understand catalyst deactivation and the elementary surface processes involved in chain growth. Isotopic tracers are used in conjunction with transient-response techniques in this study of Fischer-Tropsch synthesis over Ru/TiO{sub 2} catalysts. Experiments are conducted at a total pressure of 1 atmosphere, reaction temperatures of 453--498 K and D{sub 2}/CO (or H{sub 2}/CO) ratios of 2--5. Synthesis products are analyzed by gas chromatography or isotope-ratio gas chromatography-mass spectrometry. Rate constants for chain initiation, propagation and termination are evaluated under steady-state reaction conditions by using transients in isotopic composition. The activation energy for chain termination is much higher than that for propagation, accounting for the observed decrease in the chain growth parameter are also estimated. Coverages by reaction intermediates are also estimated. When small amounts of {sup 12}C-labelled ethylene are added to {sup 13}CO/H{sub 2} synthesis gas, ethylene acts as the sole chain initiator. Ethylene-derived carbon also accounts for 45% of the C{sub 1} monomer pool. 102 refs., 29 figs., 11 tabs.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5128268
• Report Number(s): LBL-31822; ON: DE92017085
• Country of Publication: United States
• Language: English

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CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
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KINETICS
MASS SPECTROSCOPY
METALS
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ORGANIC COMPOUNDS
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OXYGEN COMPOUNDS
PLATINUM METALS
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TITANIUM COMPOUNDS
TITANIUM OXIDES
TRACER TECHNIQUES
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TRANSITION ELEMENTS