Fischer–Tropsch Synthesis: Deuterium Kinetic Isotope Study for Hydrogenation of Carbon Oxides Over Cobalt and Iron Catalysts

Gnanamani, Muthu Kumaran; Jacobs, Gary; Shafer, Wilson D.; Sparks, Dennis E.; Davis, Burtron H.

doi:10.1007/s10562-011-0673-4

Cited by 22 publications

(21 citation statements)

References 39 publications

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“…As a consequence, the H/C molar ratio on the catalyst surface is decreased, leading to a drop in CO2 conversion. This is in agreement with numerous experimental [30][31][32][33] and theoretical [34,35] investigations that reported a drop in CO2 conversion with a decrease in H2/CO2 molar ratio. The decrease in CO2 conversion with potassium addition was also reported by Owen et al [13] and Shi et al [8] on Co/SiO2 and CoCu/TiO2 catalysts, respectively.…”

Section: Effect Of Pressuresupporting

confidence: 93%

Effect of Operating Temperature, Pressure and Potassium Loading on the Performance of Silica-Supported Cobalt Catalyst in CO2 Hydrogenation to Hydrocarbon Fuel

Iloy

Jalama

2019

Catalysts

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Potassium (1–5 wt.%)-promoted and unpromoted Co/SiO2 catalysts were prepared by impregnation method and characterized by nitrogen physisorption, temperature-programmed reduction (TPR), CO2 temperature-programmed desorption (TPD), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. They were evaluated for CO2 hydrogenation in a fixed bed reactor from 180 to 300 °C within a pressure range of 1–20 bar. The yield for hydrocarbon products other than methane (C2+) was found to increase with an increase in the operating temperature and went through a maximum of approximately 270 °C. It did not show any significant dependency on the operating pressure and decreased at potassium loadings beyond 1 wt.%. Potassium was found to enhance the catalyst ability to adsorb CO2, but limited the reduction of cobalt species during the activation process. The improved CO2 adsorption resulted in a decrease in surface H/C ratio, the latter of which enhanced the formation of C2+ hydrocarbons. The highest C2+ yield was obtained on the catalyst promoted with 1 wt.% of potassium and operated at an optimal temperature of 270 °C and a pressure of 1 bar.

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Section: Effect Of Pressuresupporting

confidence: 93%

Effect of Operating Temperature, Pressure and Potassium Loading on the Performance of Silica-Supported Cobalt Catalyst in CO2 Hydrogenation to Hydrocarbon Fuel

Iloy

Jalama

2019

Catalysts

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“…The KIE values for the propagation reactions decrease with the increasing carbon number. A similar phenomenon was observed for CO 2 hydrogenation on both Co and Fe catalysts [32]. An inverse KIE (i.e., 0.69) of the C 1 + C 1 coupling reaction is observed experimentally.…”

Section: Analysis Of Kinetic Isotope Effectsupporting

confidence: 78%

Investigation of C1 + C1 Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study

Yang

Holmén

et al. 2019

Catalysts

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Understanding the chain growth mechanism is of vital importance for the development of catalysts with enhanced selectivity towards long-chain products in cobalt-catalyzed Fischer-Tropsch synthesis. Herein, we discriminate various C1 + C1 coupling reactions by theoretical calculations and kinetic isotope experiments. CHx(x=0−3), CO, HCO, COH, and HCOH are considered as the chain growth monomer respectively, and 24 possible coupling reactions are first investigated by theoretical calculations. Eight possible C1 + C1 coupling reactions are suggested to be energetically favorable because of the relative low reaction barriers. Moreover, five pathways are excluded where the C1 monomers show low thermodynamic stability. Effective chain propagation rates are calculated by deconvoluting from reaction rates of products, and an inverse kinetic isotope effect of the C1 + C1 coupling reaction is observed. The theoretical kinetic isotope effect of CO + CH2 is inverse, which is consistent with the experimental observation. Thus, the CO + CH2 pathway, owing to the relatively lower barrier, the high thermodynamic stability, and the inverse kinetic isotope effect, is suggested to be a favorable pathway.

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“…The construction of these responses requires no calibration of the corresponding MS signals, as opposed to the case where steady-state kinetic rates of CD 4 and CH 4 must be estimated via the calibration of the signal from the gas analyzer used (e.g. MS, GC or FTIR) [34]. Also, this SSITKA step-gas switches methodology allows within~15 min of experimentation time to obtain the necessary s CH4 and s CD4 parameters required for the estimation of D-KIE (see Fig.…”

Section: Deuterium Kinetic Isotopic Effect (D-kie)mentioning

confidence: 99%

Deactivation of Co/γ-Al2O3 in CO methanation studied by transient isotopic experiments: The effect of Co particle size

Petallidou

Vasiliades

Efstathiou

2020

Journal of Catalysis

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SSITKA coupled with transient isothermal (TIH) and temperature-programmed hydrogenation (TPH) were used to investigate the influence of Co particle size (d Co = 11-21 nm) and time-on-stream, TOS (up to 25 h) on important kinetic parameters of CO methanation at 230°C on Co/c-Al 2 O 3. TOF CO and TOF CH4 were independent of d Co and decreased with TOS. The h CO and h CHx (active COs and CH x-s) slightly increased with d Co as opposed to h CxHy (inactive species), which remained practically constant. On the contrary, h CHx and h CxHy largely decreased and increased, respectively, while h CO stayed practically constant with TOS. An inverse D-KIE independent of d Co was estimated by a novel 13 CO/D 2-SSITKA experiment, reported for the first time to the best of our knowledge. The reason of catalyst deactivation was the decrease of k CHx (hydrogenation of-CH x) likely because of the influence of-C x H y on the bonding of active species and on h H (a decrease was determined).

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Fischer–Tropsch Synthesis: Deuterium Kinetic Isotope Study for Hydrogenation of Carbon Oxides Over Cobalt and Iron Catalysts

Cited by 22 publications

References 39 publications

Effect of Operating Temperature, Pressure and Potassium Loading on the Performance of Silica-Supported Cobalt Catalyst in CO2 Hydrogenation to Hydrocarbon Fuel

Effect of Operating Temperature, Pressure and Potassium Loading on the Performance of Silica-Supported Cobalt Catalyst in CO2 Hydrogenation to Hydrocarbon Fuel

Investigation of C1 + C1 Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study

Deactivation of Co/γ-Al2O3 in CO methanation studied by transient isotopic experiments: The effect of Co particle size

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