Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst
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2020
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In this study we investigate performance characteristics (catalyst effectiveness, CH4 selectivity, and hydrocarbon product distribution) of with a highly active Co/Re/Al(2)O(3 )catalyst particle for Fischer-Tropsch synthesis. In numerical simulations we utilize kinetic parameters for CO consumption rate, CH4 formation rate and hydrocarbon formation rates (C-2+ hydrocarbons) determined from experiments with this catalyst to study effects of catalyst activity, catalyst particle shape (sphere, slab, solid and hollow cylinder), size (i.e. diffusion length), catalyst distribution (uniform vs. eggshell type distribution for a spherical particle) and process conditions (temperature, pressure, syngas composition and conversion level) on the catalyst performance. With increase in Thiele modulus (i.e. particle size at a fixed set of process conditions) we observe increasing H-2/CO ratio profile towards the center of the particle resulting in increase of local and average CH4 selectivity. The goa...l is to find conditions which allow one to use sufficiently large particles to reduce pressure drop, while avoiding negative influence of diffusional limitations on selectivity and activity. For each catalyst particle shape we determined values of Thiele modulus, i.e. characteristic length of diffusion, corresponding to the upper limit of the kinetic region, and investigated how it changes with operating conditions. We found that simultaneous increase of pressure and the use of syngas with H-2/CO feed ratio of 1.4-1.7 is the best strategy for mitigating the negative impact of intraparticle diffusional limitations on CH4 selectivity. For a spherical particle of 1 mm in diameter, one can achieve CH4 selectivity of 5.6% with catalyst effectiveness factor of 1.07 at the reactor inlet by operating at 50 bar, 473 K and H-2/CO = 1.4.
Ključne reči:
Fischer-Tropsch synthesis / Single cobalt catalyst particle / Intraparticle diffusion / Catalyst effectiveness factor / Methane selectivityIzvor:
Catalysis Today, 2020, 343, 146-155Izdavač:
- Elsevier, Amsterdam
Finansiranje / projekti:
- Qatar National Research Fund (a member of the Qatar Foundation) [NPRP 7-559-2-211]
DOI: 10.1016/j.cattod.2018.10.069
ISSN: 0920-5861
WoS: 000519970100016
Scopus: 2-s2.0-85056588794
Institucija/grupa
Tehnološko-metalurški fakultetTY - JOUR AU - Bukur, Dragomir B. AU - Mandić, Miloš AU - Todić, Branislav AU - Nikačević, Nikola PY - 2020 UR - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4452 AB - In this study we investigate performance characteristics (catalyst effectiveness, CH4 selectivity, and hydrocarbon product distribution) of with a highly active Co/Re/Al(2)O(3 )catalyst particle for Fischer-Tropsch synthesis. In numerical simulations we utilize kinetic parameters for CO consumption rate, CH4 formation rate and hydrocarbon formation rates (C-2+ hydrocarbons) determined from experiments with this catalyst to study effects of catalyst activity, catalyst particle shape (sphere, slab, solid and hollow cylinder), size (i.e. diffusion length), catalyst distribution (uniform vs. eggshell type distribution for a spherical particle) and process conditions (temperature, pressure, syngas composition and conversion level) on the catalyst performance. With increase in Thiele modulus (i.e. particle size at a fixed set of process conditions) we observe increasing H-2/CO ratio profile towards the center of the particle resulting in increase of local and average CH4 selectivity. The goal is to find conditions which allow one to use sufficiently large particles to reduce pressure drop, while avoiding negative influence of diffusional limitations on selectivity and activity. For each catalyst particle shape we determined values of Thiele modulus, i.e. characteristic length of diffusion, corresponding to the upper limit of the kinetic region, and investigated how it changes with operating conditions. We found that simultaneous increase of pressure and the use of syngas with H-2/CO feed ratio of 1.4-1.7 is the best strategy for mitigating the negative impact of intraparticle diffusional limitations on CH4 selectivity. For a spherical particle of 1 mm in diameter, one can achieve CH4 selectivity of 5.6% with catalyst effectiveness factor of 1.07 at the reactor inlet by operating at 50 bar, 473 K and H-2/CO = 1.4. PB - Elsevier, Amsterdam T2 - Catalysis Today T1 - Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst EP - 155 SP - 146 VL - 343 DO - 10.1016/j.cattod.2018.10.069 ER -
@article{ author = "Bukur, Dragomir B. and Mandić, Miloš and Todić, Branislav and Nikačević, Nikola", year = "2020", abstract = "In this study we investigate performance characteristics (catalyst effectiveness, CH4 selectivity, and hydrocarbon product distribution) of with a highly active Co/Re/Al(2)O(3 )catalyst particle for Fischer-Tropsch synthesis. In numerical simulations we utilize kinetic parameters for CO consumption rate, CH4 formation rate and hydrocarbon formation rates (C-2+ hydrocarbons) determined from experiments with this catalyst to study effects of catalyst activity, catalyst particle shape (sphere, slab, solid and hollow cylinder), size (i.e. diffusion length), catalyst distribution (uniform vs. eggshell type distribution for a spherical particle) and process conditions (temperature, pressure, syngas composition and conversion level) on the catalyst performance. With increase in Thiele modulus (i.e. particle size at a fixed set of process conditions) we observe increasing H-2/CO ratio profile towards the center of the particle resulting in increase of local and average CH4 selectivity. The goal is to find conditions which allow one to use sufficiently large particles to reduce pressure drop, while avoiding negative influence of diffusional limitations on selectivity and activity. For each catalyst particle shape we determined values of Thiele modulus, i.e. characteristic length of diffusion, corresponding to the upper limit of the kinetic region, and investigated how it changes with operating conditions. We found that simultaneous increase of pressure and the use of syngas with H-2/CO feed ratio of 1.4-1.7 is the best strategy for mitigating the negative impact of intraparticle diffusional limitations on CH4 selectivity. For a spherical particle of 1 mm in diameter, one can achieve CH4 selectivity of 5.6% with catalyst effectiveness factor of 1.07 at the reactor inlet by operating at 50 bar, 473 K and H-2/CO = 1.4.", publisher = "Elsevier, Amsterdam", journal = "Catalysis Today", title = "Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst", pages = "155-146", volume = "343", doi = "10.1016/j.cattod.2018.10.069" }
Bukur, D. B., Mandić, M., Todić, B.,& Nikačević, N.. (2020). Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst. in Catalysis Today Elsevier, Amsterdam., 343, 146-155. https://doi.org/10.1016/j.cattod.2018.10.069
Bukur DB, Mandić M, Todić B, Nikačević N. Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst. in Catalysis Today. 2020;343:146-155. doi:10.1016/j.cattod.2018.10.069 .
Bukur, Dragomir B., Mandić, Miloš, Todić, Branislav, Nikačević, Nikola, "Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst" in Catalysis Today, 343 (2020):146-155, https://doi.org/10.1016/j.cattod.2018.10.069 . .