Fischer-Tropsch synthesis: Direct cobalt nitrate reduction of promoted Co/TiO2 catalysts
Abstract
The effect of the direct reduction of cobalt nitrate versus the more conventional calcination/reduction treatment has been investigated. Porosity properties of the catalysts are not significantly modified by avoiding the calcination step, as similar BET surface area, pore volume and pore diameter are obtained for the activated catalysts. In contrast, the cobalt reducibility decreases, but smaller cobalt particles size and higher dispersion are obtained. The reduction phenomena occurring for the uncalcined catalysts are more complex because of the additional nitrate decomposition steps. TPR-MS and TPR-XANES point out that CoOx intermediate species are formed during the reductive nitrate decomposition. However, these species are oxidized by NOX (formed by nitrate decomposition) to spinel type Co3O4, which is then converted to CoO prior to the final reduction step to Co0. The addition of promoters (Pt, Re, Ru, Ag) improves the cobalt reducibility, especially by shifting the final reduction step (i.e., CoO to Co0) to lower temperature. FT activity testing data show that activated uncalcined catalysts have higher CO conversion following the initial decline and leveling off period relative to the activated calcined catalyst. We find that the best performance is achieved with uncalcined Pt-12%Co/TiO2. This catalyst has the highest CO steady state conversion,more »
- Authors:
-
- Univ. of Texas (UTSA), San Antonio, TX (United States). Dept. of Mechanical Engineering
- Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research
- Univ. of Texas (UTSA), San Antonio, TX (United States). Dept. of Biomedical Engineering
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Univ. of Texas (UTSA), San Antonio, TX (United States). Dept. of Mechanical Engineering, and Dept. of Biomedical Engineering
- Publication Date:
- Research Org.:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Org.:
- Univ. of Texas, San Antonio, TX (United States); USDOE Office of Fossil Energy (FE); USDOE Office of Science (SC), Basic Energy Sciences (BES)
- OSTI Identifier:
- 1531155
- Alternate Identifier(s):
- OSTI ID: 1635990
- Grant/Contract Number:
- AC02-06CH11357
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Fuel
- Additional Journal Information:
- Journal Volume: 245; Journal Issue: C; Journal ID: ISSN 0016-2361
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; titania; Fischer-Tropsch synthesis; TPR-EXAFS; TPR-MS; TPR-XANES; cobalt; direct cobalt nitrate reduction; platinum; promoters
Citation Formats
Mehrbod, Mohammad, Martinelli, Michela, Martino, Annabelle G., Cronauer, Donald C., Jeremy Kropf, A., Marshall, Christopher L., and Jacobs, Gary. Fischer-Tropsch synthesis: Direct cobalt nitrate reduction of promoted Co/TiO2 catalysts. United States: N. p., 2019.
Web. doi:10.1016/j.fuel.2019.02.083.
Mehrbod, Mohammad, Martinelli, Michela, Martino, Annabelle G., Cronauer, Donald C., Jeremy Kropf, A., Marshall, Christopher L., & Jacobs, Gary. Fischer-Tropsch synthesis: Direct cobalt nitrate reduction of promoted Co/TiO2 catalysts. United States. https://doi.org/10.1016/j.fuel.2019.02.083
Mehrbod, Mohammad, Martinelli, Michela, Martino, Annabelle G., Cronauer, Donald C., Jeremy Kropf, A., Marshall, Christopher L., and Jacobs, Gary. Mon .
"Fischer-Tropsch synthesis: Direct cobalt nitrate reduction of promoted Co/TiO2 catalysts". United States. https://doi.org/10.1016/j.fuel.2019.02.083. https://www.osti.gov/servlets/purl/1531155.
@article{osti_1531155,
title = {Fischer-Tropsch synthesis: Direct cobalt nitrate reduction of promoted Co/TiO2 catalysts},
author = {Mehrbod, Mohammad and Martinelli, Michela and Martino, Annabelle G. and Cronauer, Donald C. and Jeremy Kropf, A. and Marshall, Christopher L. and Jacobs, Gary},
abstractNote = {The effect of the direct reduction of cobalt nitrate versus the more conventional calcination/reduction treatment has been investigated. Porosity properties of the catalysts are not significantly modified by avoiding the calcination step, as similar BET surface area, pore volume and pore diameter are obtained for the activated catalysts. In contrast, the cobalt reducibility decreases, but smaller cobalt particles size and higher dispersion are obtained. The reduction phenomena occurring for the uncalcined catalysts are more complex because of the additional nitrate decomposition steps. TPR-MS and TPR-XANES point out that CoOx intermediate species are formed during the reductive nitrate decomposition. However, these species are oxidized by NOX (formed by nitrate decomposition) to spinel type Co3O4, which is then converted to CoO prior to the final reduction step to Co0. The addition of promoters (Pt, Re, Ru, Ag) improves the cobalt reducibility, especially by shifting the final reduction step (i.e., CoO to Co0) to lower temperature. FT activity testing data show that activated uncalcined catalysts have higher CO conversion following the initial decline and leveling off period relative to the activated calcined catalyst. We find that the best performance is achieved with uncalcined Pt-12%Co/TiO2. This catalyst has the highest CO steady state conversion, which is 1.2 times higher than the Pt-promoted calcined catalyst. Moreover, its deactivation rate is 0.13%/h compared to 0.2%/h for the corresponding calcined catalyst. The difference in the catalytic activity is even higher for the un-promoted samples, where the activated uncalcined catalyst has almost double the CO conversion as compared to its calcined counterpart. Finally, the addition of other promoters such as Ru, Re and Ag has no significant effect on catalytic activity.},
doi = {10.1016/j.fuel.2019.02.083},
journal = {Fuel},
number = C,
volume = 245,
place = {United States},
year = {Mon Feb 25 00:00:00 EST 2019},
month = {Mon Feb 25 00:00:00 EST 2019}
}
Web of Science