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Title: Fischer–Tropsch Synthesis: XANES Spectra of Potassium in Promoted Precipitated Iron Catalysts as a Function of Time On-stream

XANES K-edge spectra of potassium promoter in precipitated Fe catalysts were acquired following activation by carburization in CO and as a function of time on-stream during the course of a Fischer–Tropsch synthesis run for a 100Fe:2K catalyst by withdrawing catalysts, sealed in wax product, for analysis. CO-activated and end-of-run spectra of the catalyst were also obtained for a 100Fe:5K catalyst. Peaks representing electronic transitions and multiple scattering were observed and resembled reference spectra for potassium carbonate or potassium formate. The shift in the multiple scattering peak to higher energy was consistent with sintering of potassium promoter during the course of the reaction test. The catalyst, however, retained its carbidic state, as demonstrated by XANES and EXAFS spectra at the iron K-edge, suggesting that sintering of potassium did not adversely affect the carburization rate, which is important for preventing iron carbides from oxidizing. This method serves as a starting point for developing better understanding of the chemical state and changes in structure occurring with alkali promoter.
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [4] ;  [4] ;  [2]
  1. Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research; Univ. of Texas, San Antonio, TX (United States). Dept. of Biomedical and Chemical Engineering
  2. Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
  4. Canadian Light Sources, Inc., Saskatoon, SK (Canada)
Publication Date:
Report Number(s):
BNL-203462-2018-JAAM
Journal ID: ISSN 1011-372X
Grant/Contract Number:
SC0012704; AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Catalysis Letters
Additional Journal Information:
Journal Volume: 147; Journal Issue: 8; Journal ID: ISSN 1011-372X
Publisher:
Springer
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Commonwealth of Kentucky; Canadian Light Sources, Inc., Saskatoon, SK (Canada)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 43 PARTICLE ACCELERATORS; Fischer-Tropsch synthesis; iron-based catalyst; potassium promoter; olefin selectivity; XANES/EXAFS
OSTI Identifier:
1433948

Jacobs, Gary, Pendyala, Venkat Ramana Rao, Martinelli, Michela, Shafer, Wilson D., Gnanamani, Muthu Kumaran, Khalid, Syed, MacLennan, Aimee, Hu, Yongfeng, and Davis, Burtron H.. Fischer–Tropsch Synthesis: XANES Spectra of Potassium in Promoted Precipitated Iron Catalysts as a Function of Time On-stream. United States: N. p., Web. doi:10.1007/s10562-017-2090-9.
Jacobs, Gary, Pendyala, Venkat Ramana Rao, Martinelli, Michela, Shafer, Wilson D., Gnanamani, Muthu Kumaran, Khalid, Syed, MacLennan, Aimee, Hu, Yongfeng, & Davis, Burtron H.. Fischer–Tropsch Synthesis: XANES Spectra of Potassium in Promoted Precipitated Iron Catalysts as a Function of Time On-stream. United States. doi:10.1007/s10562-017-2090-9.
Jacobs, Gary, Pendyala, Venkat Ramana Rao, Martinelli, Michela, Shafer, Wilson D., Gnanamani, Muthu Kumaran, Khalid, Syed, MacLennan, Aimee, Hu, Yongfeng, and Davis, Burtron H.. 2017. "Fischer–Tropsch Synthesis: XANES Spectra of Potassium in Promoted Precipitated Iron Catalysts as a Function of Time On-stream". United States. doi:10.1007/s10562-017-2090-9. https://www.osti.gov/servlets/purl/1433948.
@article{osti_1433948,
title = {Fischer–Tropsch Synthesis: XANES Spectra of Potassium in Promoted Precipitated Iron Catalysts as a Function of Time On-stream},
author = {Jacobs, Gary and Pendyala, Venkat Ramana Rao and Martinelli, Michela and Shafer, Wilson D. and Gnanamani, Muthu Kumaran and Khalid, Syed and MacLennan, Aimee and Hu, Yongfeng and Davis, Burtron H.},
abstractNote = {XANES K-edge spectra of potassium promoter in precipitated Fe catalysts were acquired following activation by carburization in CO and as a function of time on-stream during the course of a Fischer–Tropsch synthesis run for a 100Fe:2K catalyst by withdrawing catalysts, sealed in wax product, for analysis. CO-activated and end-of-run spectra of the catalyst were also obtained for a 100Fe:5K catalyst. Peaks representing electronic transitions and multiple scattering were observed and resembled reference spectra for potassium carbonate or potassium formate. The shift in the multiple scattering peak to higher energy was consistent with sintering of potassium promoter during the course of the reaction test. The catalyst, however, retained its carbidic state, as demonstrated by XANES and EXAFS spectra at the iron K-edge, suggesting that sintering of potassium did not adversely affect the carburization rate, which is important for preventing iron carbides from oxidizing. This method serves as a starting point for developing better understanding of the chemical state and changes in structure occurring with alkali promoter.},
doi = {10.1007/s10562-017-2090-9},
journal = {Catalysis Letters},
number = 8,
volume = 147,
place = {United States},
year = {2017},
month = {6}
}

Works referenced in this record:

WinXAS a Program for X-ray Absorption Spectroscopy Data Analysis under MS-Windows
journal, March 1998