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Title: Effect of potassium promotion on iron-based catalysts for Fischer-Tropsch synthesis

Abstract

The effect of potassium on Fischer-Tropsch catalyst activity, kinetic parameters, and selectivity has been investigated for a precipitated iron catalyst that was employed with low H{sub 2}/CO ratio synthesis gas. A wide range of synthesis gas conversions have been obtained by varying space velocities over catalysts with various potassium loadings. Differing trends in catalyst activity with potassium loading were observed depending on the space velocity of synthesis gas conversion. As potassium loading increased, the catalyst activity either decreased (low conversion), passed through a maximum (intermediate conversion), or increased (high conversion). This is shown to be a result of the increasing dependency of the Fischer-Tropsch synthesis on the hydrogen formed by the water-gas shift reaction with increasing synthesis gas conversions. Both the rate constant and the adsorption parameter in a common two-parameter Fischer-Tropsch rate expression decreased with potassium loading; therefore, observed maxima in Fischer-Tropsch rate with potassium loading can be due to the opposing influences of these parameters. The effect of potassium on alkene selectivity was dependent on the number of carbon atoms of the hydrocarbons as well as the carbon monoxide conversion level. The extent of isomerization of 1-alkene product decreased with potassium loading, while the selectivity to methane decreasedmore » only slightly with increasing potassium content at CO conversions about 50% and higher.« less

Authors:
; ;  [1]
  1. Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research
Publication Date:
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
316302
DOE Contract Number:  
AC22-94PC94055
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 180; Journal Issue: 1; Other Information: DN: Paper presented at the Fischer-Tropsch conversion of gas to liquid symposium, March 10--13, 1997, Houston, TX (US); PBD: 15 Nov 1998
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 10 SYNTHETIC FUELS; FISCHER-TROPSCH SYNTHESIS; CATALYSTS; POTASSIUM; PROMOTERS; IRON; CARBON MONOXIDE; METHANATION; CATALYTIC EFFECTS; CHEMICAL REACTION KINETICS; METHANE; ALKENES

Citation Formats

Raje, A P, O`Brien, R J, and Davis, B H. Effect of potassium promotion on iron-based catalysts for Fischer-Tropsch synthesis. United States: N. p., 1998. Web. doi:10.1006/jcat.1998.2259.
Raje, A P, O`Brien, R J, & Davis, B H. Effect of potassium promotion on iron-based catalysts for Fischer-Tropsch synthesis. United States. doi:10.1006/jcat.1998.2259.
Raje, A P, O`Brien, R J, and Davis, B H. Sun . "Effect of potassium promotion on iron-based catalysts for Fischer-Tropsch synthesis". United States. doi:10.1006/jcat.1998.2259.
@article{osti_316302,
title = {Effect of potassium promotion on iron-based catalysts for Fischer-Tropsch synthesis},
author = {Raje, A P and O`Brien, R J and Davis, B H},
abstractNote = {The effect of potassium on Fischer-Tropsch catalyst activity, kinetic parameters, and selectivity has been investigated for a precipitated iron catalyst that was employed with low H{sub 2}/CO ratio synthesis gas. A wide range of synthesis gas conversions have been obtained by varying space velocities over catalysts with various potassium loadings. Differing trends in catalyst activity with potassium loading were observed depending on the space velocity of synthesis gas conversion. As potassium loading increased, the catalyst activity either decreased (low conversion), passed through a maximum (intermediate conversion), or increased (high conversion). This is shown to be a result of the increasing dependency of the Fischer-Tropsch synthesis on the hydrogen formed by the water-gas shift reaction with increasing synthesis gas conversions. Both the rate constant and the adsorption parameter in a common two-parameter Fischer-Tropsch rate expression decreased with potassium loading; therefore, observed maxima in Fischer-Tropsch rate with potassium loading can be due to the opposing influences of these parameters. The effect of potassium on alkene selectivity was dependent on the number of carbon atoms of the hydrocarbons as well as the carbon monoxide conversion level. The extent of isomerization of 1-alkene product decreased with potassium loading, while the selectivity to methane decreased only slightly with increasing potassium content at CO conversions about 50% and higher.},
doi = {10.1006/jcat.1998.2259},
journal = {Journal of Catalysis},
number = 1,
volume = 180,
place = {United States},
year = {1998},
month = {11}
}