Mo-Fe catalysts supported on activated carbon for synthesis of liquid fuels by the Fischer-Tropsch process: effect of Mo addition on reducibility, activity, and hydrocarbon selectivity
Abstract
The effects of Mo loading (0-12 wt %) on the properties of activated-carbon- (AC-) supported Fe-Cu-K catalysts and their performance for Fischer-Tropsch synthesis are studied. Physicochemical properties studied include particle size, reducibility, and dispersion, and catalytic properties include activity, selectivity, and stability. Catalysts were characterized by N{sub 2} adsorption, energy-dispersive spectroscopy, X-ray diffraction (XRD), H{sub 2} temperature-programmed reduction (TPR), and CO chemisorption. Catalyst performance was studied at 310-320{sup o}C, 2.2 MPa, 3 Nl/g-cat/h, and H{sub 2}/CO = 0.9. Reaction results in a fixed-bed reactor show that addition of 6% Mo into the Fe-Cu-K/AC catalyst improves catalyst stability without sacrificing activity, but activity is suppressed dramatically on a 12% Mo-loaded catalyst. Detectable hydrocarbons of C{sub 1} to C{sub 34} are produced on the Fe-Cu-K/AC catalysts with or without Mo. However, the addition of Mo results in the production of more CH{sub 4} and less C{sub 5+} hydrocarbons. The Mo promoter greatly enhances secondary reactions of olefins, leading to a large amount of internal olefins (i.e., other than 1-olefins) in the product. TPR shows that a strong interaction between Fe and Mo oxides is present, and the extent of reduction of Fe is suppressed after addition of Mo to the Fe-Cu-K catalyst.more »
- Authors:
- West Virginia University, Morgantown, WV (United States). Department of Chemical Engineering
- Publication Date:
- OSTI Identifier:
- 20838250
- Resource Type:
- Journal Article
- Resource Relation:
- Journal Name: Energy and Fuels; Journal Volume: 20; Journal Issue: 6; Other Information: dady.dadyburjor@mail.wvu.edu
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 01 COAL, LIGNITE, AND PEAT; MOLYBDENUM; IRON; CATALYSTS; CATALYST SUPPORTS; ACTIVATED CARBON; FISCHER-TROPSCH SYNTHESIS; LIQUID FUELS; CATALYTIC EFFECTS; SPECIFICITY; PROMOTERS; STABILITY
Citation Formats
Wenping Ma, Edwin L. Kugler, James Wright, and Dady B. Dadyburjor. Mo-Fe catalysts supported on activated carbon for synthesis of liquid fuels by the Fischer-Tropsch process: effect of Mo addition on reducibility, activity, and hydrocarbon selectivity. United States: N. p., 2006.
Web.
Wenping Ma, Edwin L. Kugler, James Wright, & Dady B. Dadyburjor. Mo-Fe catalysts supported on activated carbon for synthesis of liquid fuels by the Fischer-Tropsch process: effect of Mo addition on reducibility, activity, and hydrocarbon selectivity. United States.
Wenping Ma, Edwin L. Kugler, James Wright, and Dady B. Dadyburjor. Fri .
"Mo-Fe catalysts supported on activated carbon for synthesis of liquid fuels by the Fischer-Tropsch process: effect of Mo addition on reducibility, activity, and hydrocarbon selectivity". United States.
doi:.
@article{osti_20838250,
title = {Mo-Fe catalysts supported on activated carbon for synthesis of liquid fuels by the Fischer-Tropsch process: effect of Mo addition on reducibility, activity, and hydrocarbon selectivity},
author = {Wenping Ma and Edwin L. Kugler and James Wright and Dady B. Dadyburjor},
abstractNote = {The effects of Mo loading (0-12 wt %) on the properties of activated-carbon- (AC-) supported Fe-Cu-K catalysts and their performance for Fischer-Tropsch synthesis are studied. Physicochemical properties studied include particle size, reducibility, and dispersion, and catalytic properties include activity, selectivity, and stability. Catalysts were characterized by N{sub 2} adsorption, energy-dispersive spectroscopy, X-ray diffraction (XRD), H{sub 2} temperature-programmed reduction (TPR), and CO chemisorption. Catalyst performance was studied at 310-320{sup o}C, 2.2 MPa, 3 Nl/g-cat/h, and H{sub 2}/CO = 0.9. Reaction results in a fixed-bed reactor show that addition of 6% Mo into the Fe-Cu-K/AC catalyst improves catalyst stability without sacrificing activity, but activity is suppressed dramatically on a 12% Mo-loaded catalyst. Detectable hydrocarbons of C{sub 1} to C{sub 34} are produced on the Fe-Cu-K/AC catalysts with or without Mo. However, the addition of Mo results in the production of more CH{sub 4} and less C{sub 5+} hydrocarbons. The Mo promoter greatly enhances secondary reactions of olefins, leading to a large amount of internal olefins (i.e., other than 1-olefins) in the product. TPR shows that a strong interaction between Fe and Mo oxides is present, and the extent of reduction of Fe is suppressed after addition of Mo to the Fe-Cu-K catalyst. CO-chemisorption and XRD studies show increased iron dispersion and decreased particle size of the iron carbide and iron oxide after the addition of Mo. Segregation of iron active sites, thereby preventing them from agglomerating, and a larger number of active sites on the 6% Mo catalyst are possible reasons for the improved stability and higher activity of Mo-promoted catalysts. 54 refs., 5 figs., 6 tabs.},
doi = {},
journal = {Energy and Fuels},
number = 6,
volume = 20,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}
-
The effect of potassium on the activity, selectivity, and distribution of products (hydrocarbons and oxygenates) was studied over iron catalysts supported on activated carbon (AC) for Fischer-Tropsch synthesis (FTS). This is part of a wider study on the incremental effects of components (including the support) of a multicomponent (Fe-Cu-Mo-K/AC) FTS catalyst. The range of potassium loading used was 0-2 wt%. A fixed-bed reactor was used under the conditions of 260-300{sup o}C, 300 psig, and 3 Nl/g cat/h, using syngas with a H{sub 2}/CO molar feed ratio of 0.9. Both FTS and water-gas shift activities increase after the addition of 0.9more »
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Hydrocarbon selectivity model for gas-solid Fischer-Tropsch synthesis on precipitated iron catalysts
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 bothmore » -
Influence of the support on the activity and selectivity of high dispersion Fe catalysts in the Fischer-Tropsch reaction
In order to study the influence of the support on high dispersion catalysts used for the CO hydrogenation reaction, two catalysts, Fe/SiO{sub 2} and Fe/Al{sub 2}O{sub 3}, were prepared by the dry impregnation method. Selective chemisorption of CO, volumetric oxidation, and Moessbauer spectroscopy were used to determine the Fe species present as well as the metallic crystal size, the degree of dispersion, and the reduction percentage. The presence of small Fe{sup 0} crystallites with high dispersion was determined in both catalysts. Reaction rates were measured in a differential reactor and significant differences, about one order of magnitude less for themore »