skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Hydrocarbon selectivity model for gas-solid Fischer-Tropsch synthesis on precipitated iron catalysts

Abstract

The kinetics of the gas-solid Fischer-Tropsch (FT) synthesis over a commercial Fe-Cu-K-SiO{sub 2} catalyst was studied in a continuous spinning basket reactor. Experimental conditions were varied as follows: reactor pressure of 0.8--3.2 MPa, H{sub 2}/CO feed ratio = 0.5--2.0, and a space velocity of 0.5--2.0 {times} 10{sup {minus}3} Nm{sup 3}/kg{sub cat} s at a constant temperature of 523 K. A new product distribution model for linear hydrocarbons is proposed. Deviations from conventional Anderson-Schulz-Flory distribution can be quantitatively described with an {alpha}-olefin readsorption product distribution model. The experimentally observed relatively high yield of methane, relatively low yield of ethene, and both the exponential decrease of the olefin-to-paraffin ratio and the change of the chain growth parameter with chain length can all be predicted from this new model. It combines a mechanistic model of olefin readsorption with kinetics of chain growth and termination on the same catalytic sites. The hydrocarbon formation is based on the surface carbide mechanism by CH{sub 2} insertion. The olefin readsorption rate depends on the chain length because of increasing physisorption strength on the catalyst surface and increasing solubility in FT wax with increasing chain length. Interfacial concentrations of reactive olefins near the gas-wax and wax-catalyst surface aremore » used in the kinetic model. With optimization of three parameters per experimental product distribution, the olefin readsorption product distribution model proved to predict product selectivities accurately over the entire range of experimental conditions. The relative deviations are 10.1% and 9.1% for the selectivity to paraffins and olefins with n < 11, respectively.« less

Authors:
;  [1]
  1. Univ. of Groningen (Netherlands). Dept. of Chemical Engineering
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
345335
Resource Type:
Journal Article
Journal Name:
Industrial and Engineering Chemistry Research
Additional Journal Information:
Journal Volume: 38; Journal Issue: 4; Other Information: PBD: Apr 1999
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 10 SYNTHETIC FUELS; FISCHER-TROPSCH SYNTHESIS; MATHEMATICAL MODELS; CATALYSTS; CHEMICAL REACTION KINETICS; CHEMICAL REACTION YIELD; NATURAL GAS

Citation Formats

Laan, G.P. van der, and Beenackers, A A.C.M. Hydrocarbon selectivity model for gas-solid Fischer-Tropsch synthesis on precipitated iron catalysts. United States: N. p., 1999. Web. doi:10.1021/ie980561n.
Laan, G.P. van der, & Beenackers, A A.C.M. Hydrocarbon selectivity model for gas-solid Fischer-Tropsch synthesis on precipitated iron catalysts. United States. doi:10.1021/ie980561n.
Laan, G.P. van der, and Beenackers, A A.C.M. Thu . "Hydrocarbon selectivity model for gas-solid Fischer-Tropsch synthesis on precipitated iron catalysts". United States. doi:10.1021/ie980561n.
@article{osti_345335,
title = {Hydrocarbon selectivity model for gas-solid Fischer-Tropsch synthesis on precipitated iron catalysts},
author = {Laan, G.P. van der and Beenackers, A A.C.M.},
abstractNote = {The kinetics of the gas-solid Fischer-Tropsch (FT) synthesis over a commercial Fe-Cu-K-SiO{sub 2} catalyst was studied in a continuous spinning basket reactor. Experimental conditions were varied as follows: reactor pressure of 0.8--3.2 MPa, H{sub 2}/CO feed ratio = 0.5--2.0, and a space velocity of 0.5--2.0 {times} 10{sup {minus}3} Nm{sup 3}/kg{sub cat} s at a constant temperature of 523 K. A new product distribution model for linear hydrocarbons is proposed. Deviations from conventional Anderson-Schulz-Flory distribution can be quantitatively described with an {alpha}-olefin readsorption product distribution model. The experimentally observed relatively high yield of methane, relatively low yield of ethene, and both the exponential decrease of the olefin-to-paraffin ratio and the change of the chain growth parameter with chain length can all be predicted from this new model. It combines a mechanistic model of olefin readsorption with kinetics of chain growth and termination on the same catalytic sites. The hydrocarbon formation is based on the surface carbide mechanism by CH{sub 2} insertion. The olefin readsorption rate depends on the chain length because of increasing physisorption strength on the catalyst surface and increasing solubility in FT wax with increasing chain length. Interfacial concentrations of reactive olefins near the gas-wax and wax-catalyst surface are used in the kinetic model. With optimization of three parameters per experimental product distribution, the olefin readsorption product distribution model proved to predict product selectivities accurately over the entire range of experimental conditions. The relative deviations are 10.1% and 9.1% for the selectivity to paraffins and olefins with n < 11, respectively.},
doi = {10.1021/ie980561n},
journal = {Industrial and Engineering Chemistry Research},
number = 4,
volume = 38,
place = {United States},
year = {1999},
month = {4}
}