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Title: Fischer-Tropsch synthesis: Foregoing calcination and utilizing reduction promoters leads to improved conversion and selectivity with Co/silica

Foregoing calcination and utilizing direct reduction of cobalt nitrate led to the formation of smaller cobalt oxide nanoclusters in stronger interaction with silica support as intermediates of the activation process to Co° nanoparticles; this was demonstrated by TPR, TPR-MS, TPR-XANES, and TPR-EXAFS experiments using hydrogen. These intermediate cobalt oxides included a spinel (e.g., Co 3O 4) formed from oxidation of Co 2+ species by NO 2, which in turn converted to CoO prior to formation of the metal. To improve the reducibility, metal promoters such as Pt, Re, Ru, and Ag were added. Hydrogen chemisorption and EXAFS experiments revealed smaller nanoparticles; Co-Co metal coordination numbers were significantly lower for the H 2-activated Co metal nanoparticles when direct reduction of the nitrate was used relative to H 2-activated air calcined catalysts. Comparing at the same space velocity, the best catalysts were Re and Pt promoted 12%Co/SiO 2 catalysts utilizing direct reduction of the nitrate, where initial conversions in a CSTR were up to 3.8 times higher and 71% higher than unpromoted and Pt promoted air calcined catalysts, respectively. At these conditions, methane production was lower (6.8 and 8.0% for Re and Pt promoted catalysts, respectively, by direct reduction versus 12.5 andmore » 10.1% for unpromoted and Pt promoted air calcined catalysts) and C 5+ selectivity was higher (81.2% and 81.5% for Re and Pt promoted catalysts, respectively, by direct reduction versus 73.4 and 78.8% for unpromoted and Pt promoted air calcined catalysts). In conclusion, the uncalcined catalysts were slightly less stable than the calcined samples, with the only exception being the rhenium promoted sample, where no visible deactivation was observed; this catalyst also had the highest catalytic activity on a per gram catalyst basis.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [5] ;  [5] ;  [5] ;  [6]
  1. Center for Applied Energy Research, Lexington, KY (United States)
  2. Dept. of Mechanical Engineering, San Antonio, TX (United States)
  3. Center for Applied Energy Research, Lexington, KY (United States); Henry Clay High School, Lexington, KY (United States)
  4. Politecnico di Milano, Milan (Italy)
  5. Argonne National Lab. (ANL), Argonne, IL (United States)
  6. Dept. of Mechanical Engineering, San Antonio, TX (United States); Dept. of Biomedical Engineering, San Antonio, TX (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Applied Catalysis. A, General
Additional Journal Information:
Journal Volume: 559; Journal Issue: C; Journal ID: ISSN 0926-860X
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Fischer-Tropsch synthesis; Cobalt; Silica; Platinum; Co/SiO2; Promoters; Direct cobalt nitrate reduction; TPR-XANES; TPR-EXAFS
OSTI Identifier:
1461518

Martinelli, Michela, Mehrbod, Mohammad, Dawson, Chase, Davis, Burtron H., Lietti, Luca, Cronauer, Donald C., Kropf, A. Jeremy, Marshall, Christopher L., and Jacobs, Gary. Fischer-Tropsch synthesis: Foregoing calcination and utilizing reduction promoters leads to improved conversion and selectivity with Co/silica. United States: N. p., Web. doi:10.1016/j.apcata.2018.04.013.
Martinelli, Michela, Mehrbod, Mohammad, Dawson, Chase, Davis, Burtron H., Lietti, Luca, Cronauer, Donald C., Kropf, A. Jeremy, Marshall, Christopher L., & Jacobs, Gary. Fischer-Tropsch synthesis: Foregoing calcination and utilizing reduction promoters leads to improved conversion and selectivity with Co/silica. United States. doi:10.1016/j.apcata.2018.04.013.
Martinelli, Michela, Mehrbod, Mohammad, Dawson, Chase, Davis, Burtron H., Lietti, Luca, Cronauer, Donald C., Kropf, A. Jeremy, Marshall, Christopher L., and Jacobs, Gary. 2018. "Fischer-Tropsch synthesis: Foregoing calcination and utilizing reduction promoters leads to improved conversion and selectivity with Co/silica". United States. doi:10.1016/j.apcata.2018.04.013. https://www.osti.gov/servlets/purl/1461518.
@article{osti_1461518,
title = {Fischer-Tropsch synthesis: Foregoing calcination and utilizing reduction promoters leads to improved conversion and selectivity with Co/silica},
author = {Martinelli, Michela and Mehrbod, Mohammad and Dawson, Chase and Davis, Burtron H. and Lietti, Luca and Cronauer, Donald C. and Kropf, A. Jeremy and Marshall, Christopher L. and Jacobs, Gary},
abstractNote = {Foregoing calcination and utilizing direct reduction of cobalt nitrate led to the formation of smaller cobalt oxide nanoclusters in stronger interaction with silica support as intermediates of the activation process to Co° nanoparticles; this was demonstrated by TPR, TPR-MS, TPR-XANES, and TPR-EXAFS experiments using hydrogen. These intermediate cobalt oxides included a spinel (e.g., Co3O4) formed from oxidation of Co2+ species by NO2, which in turn converted to CoO prior to formation of the metal. To improve the reducibility, metal promoters such as Pt, Re, Ru, and Ag were added. Hydrogen chemisorption and EXAFS experiments revealed smaller nanoparticles; Co-Co metal coordination numbers were significantly lower for the H2-activated Co metal nanoparticles when direct reduction of the nitrate was used relative to H2-activated air calcined catalysts. Comparing at the same space velocity, the best catalysts were Re and Pt promoted 12%Co/SiO2 catalysts utilizing direct reduction of the nitrate, where initial conversions in a CSTR were up to 3.8 times higher and 71% higher than unpromoted and Pt promoted air calcined catalysts, respectively. At these conditions, methane production was lower (6.8 and 8.0% for Re and Pt promoted catalysts, respectively, by direct reduction versus 12.5 and 10.1% for unpromoted and Pt promoted air calcined catalysts) and C5+ selectivity was higher (81.2% and 81.5% for Re and Pt promoted catalysts, respectively, by direct reduction versus 73.4 and 78.8% for unpromoted and Pt promoted air calcined catalysts). In conclusion, the uncalcined catalysts were slightly less stable than the calcined samples, with the only exception being the rhenium promoted sample, where no visible deactivation was observed; this catalyst also had the highest catalytic activity on a per gram catalyst basis.},
doi = {10.1016/j.apcata.2018.04.013},
journal = {Applied Catalysis. A, General},
number = C,
volume = 559,
place = {United States},
year = {2018},
month = {4}
}