Fischer–Tropsch reaction–diffusion in a cobalt catalyst particle: aspects of activity and selectivity for a variable chain growth probability

2012 ◽  
Vol 2 (6) ◽  
pp. 1221 ◽  
Author(s):  
David Vervloet ◽  
Freek Kapteijn ◽  
John Nijenhuis ◽  
J. Ruud van Ommen
Keyword(s):  
Cobalt Catalyst ◽  
Reaction Diffusion ◽  
Catalyst Particle ◽  
Chain Growth ◽  
Fischer Tropsch ◽  
Chain Growth Probability ◽  
Growth Probability

scholarly journals Kinetic aspects of chain growth in Fischer–Tropsch synthesis

2017 ◽  
Vol 197 ◽  
pp. 153-164 ◽  
Author(s):  
Ivo A. W. Filot ◽  
Bart Zijlstra ◽  
Robin J. P. Broos ◽  
Wei Chen ◽  
Robert Pestman ◽  
...  
Keyword(s):  
Conversion Rate ◽  
Critical Role ◽  
Chain Growth ◽  
Fischer Tropsch ◽  
Co Conversion ◽  
Chain Growth Probability ◽  
Hydrocarbon Chains ◽  
Surface Intermediates ◽  
Reaction Chain ◽  
Growth Probability

Microkinetics simulations are used to investigate the elementary reaction steps that control chain growth in the Fischer–Tropsch reaction. Chain growth in the FT reaction on stepped Ru surfaces proceeds via coupling of CH and CR surface intermediates. Essential to the growth mechanism are C–H dehydrogenation and C hydrogenation steps, whose kinetic consequences have been examined by formulating two novel kinetic concepts, the degree of chain-growth probability control and the thermodynamic degree of chain-growth probability control. For Ru the CO conversion rate is controlled by the removal of O atoms from the catalytic surface. The temperature of maximum CO conversion rate is higher than the temperature to obtain maximum chain-growth probability. Both maxima are determined by Sabatier behavior, but the steps that control chain-growth probability are different from those that control the overall rate. Below the optimum for obtaining long hydrocarbon chains, the reaction is limited by the high total surface coverage: in the absence of sufficient vacancies the CHCHR → CCHR + H reaction is slowed down. Beyond the optimum in chain-growth probability, CHCR + H → CHCHR and OH + H → H2O limit the chain-growth process. The thermodynamic degree of chain-growth probability control emphasizes the critical role of the H and free-site coverage and shows that at high temperature, chain depolymerization contributes to the decreased chain-growth probability. That is to say, during the FT reaction chain growth is much faster than chain depolymerization, which ensures high chain-growth probability. The chain-growth rate is also fast compared to chain-growth termination and the steps that control the overall CO conversion rate, which are O removal steps for Ru.

Effect of Process-Condition-Dependent Chain Growth Probability and Methane Formation on Modeling of the Fischer–Tropsch Process

2016 ◽  
Vol 30 (10) ◽  
pp. 7971-7981 ◽  
Author(s):  
Maki Matsuka ◽  
Roger D. Braddock ◽  
Toshiaki Hanaoka ◽  
Katsuya Shimura ◽  
Tomohisa Miyazawa ◽  
...  
Keyword(s):  
Process Condition ◽  
Chain Growth ◽  
Methane Formation ◽  
Fischer Tropsch ◽  
Chain Growth Probability ◽  
Growth Probability

Accumulation of liquid hydrocarbons during cobalt-catalyzed Fischer–Tropsch synthesis - influence of activity and chain growth probability

2019 ◽  
Vol 9 (15) ◽  
pp. 4047-4054 ◽  
Author(s):  
Stefan Rößler ◽  
Christoph Kern ◽  
Andreas Jess
Keyword(s):  
Tropsch Synthesis ◽  
Chain Growth ◽  
Liquid Hydrocarbons ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Chain Growth Probability ◽  
One Year ◽  
Growth Probability

It may take over one year in order to fill FT catalyst pores, depending on activity and chain growth probability.

A DFT study of the chain growth probability in Fischer–Tropsch synthesis

2008 ◽  
Vol 257 (1) ◽  
pp. 221-228 ◽  
Author(s):  
J CHENG ◽  
P HU ◽  
P ELLIS ◽  
S FRENCH ◽  
G KELLY ◽  
...  
Keyword(s):  
Tropsch Synthesis ◽  
Dft Study ◽  
Chain Growth ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Chain Growth Probability ◽  
Growth Probability

Development of kinetic model for CO hydrogenation reaction over supported Fe–Co–Mn catalyst

2017 ◽  
Vol 41 (18) ◽  
pp. 10452-10466 ◽  
Author(s):  
M. Arsalanfar ◽  
M. Abdouss ◽  
N. Mirzaei ◽  
Y. Zamani
Keyword(s):  
Kinetic Model ◽  
Production Rate ◽  
Consumption Rate ◽  
Co Hydrogenation ◽  
Hydrogenation Reaction ◽  
Chain Growth ◽  
Chain Growth Probability ◽  
Growth Probability

After determining CO consumption rate, the production rate of methane, paraffin, olefin and chain growth probability factor (α) was derived and described.

Activation Energies for Chain Growth Propagation and Termination in Fischer–Tropsch Synthesis on Iron Catalyst as a Function of Catalyst Particle Size

2016 ◽  
Vol 41 (4) ◽  
pp. 371-384 ◽  
Author(s):  
Ali Nakhaei Pour ◽  
Fatemeh Dolati
Keyword(s):  
Particle Size ◽  
Iron Catalyst ◽  
Catalyst Particle ◽  
Tropsch Synthesis ◽  
Chain Growth ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Catalyst Particle Size ◽  
Partial Pressures ◽  
Hydrocarbon Product

The influence of the catalyst particle size in determining Fischer–Tropsch synthesis (FTS) performance for nano-structured iron catalysts was investigated. The catalysts were prepared by a microemulsion method and to achieve a series of catalysts with different iron particle size, the water-to-surfactant molar ratio (W/S) in the microemulsion system varied from 4 to 12. The results demonstrate that by decreasing the levels of active phase of the iron catalyst, the termination rates for chain growth are increased compared to the propagation rates. In addition, the activation energy for chain propagation is lower than for chain termination, and this difference (Et – Ep) for the hydrocarbon product distributions which is characterised by α1, is lower than the hydrocarbon product distribution which is characterised by α2 The results indicate the H2 concentration on the catalyst surface is decreased by increasing the catalyst particle size. Thus, the dependence of α (α1, and/or α2) on H2 partial pressures is increased by decreasing of catalyst particle size and the dependence of α2 on H2 partial pressures is weaker than for α1.

Studies on Cobalt-Based Catalyst to Synthesize Heavy Hydrocarbons

2010 ◽  
Vol 132 ◽  
pp. 257-263
Author(s):  
Chen Li ◽  
Pei Li Wang ◽  
Wei Yong Ying ◽  
Ding Ye Fang
Keyword(s):  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Chain Growth ◽  
Impregnation Method ◽  
Hydrocarbon Synthesis ◽  
Chain Growth Probability ◽  
Al2o3 Support ◽  
Gas Ratio ◽  
Cobalt Species ◽  
Growth Probability

With incipient impregnation method, cobalt-based catalysts were prepared. The effects of the ZrO2 modification of support and the addition of the second metal Ru on heavy hydrocarbon synthesis were investigated in a fixed-bed reactor. The results revealed that, in cobalt-based catalysts modified with ZrO2, cobalt species were presented in the form of Co3O4, Zr species were highly dispersed or amorphous on the surface of the catalysts. ZrO2 addition also increased the desorption amount of CO, which was correlative with the degree of reduction of cobalt species. When the catalysts modified with ZrO2, the strong interaction between Co species and γ-Al2O3 support was replaced by a weak interaction between Co species and ZrO2. The ZrO2 modification increased the amount of easily reducible Co species. It is noteworthy that addition of a small quantity of Ru promoted the reduction of cobalt species, which led to the reduction temperature decreasing. For the 15w%Co0.4w%Ru4.3w%ZrO2/γ-Al2O3, at a reaction condition as feed gas ratio n(H2):n(CO)=2.0, 483K, 1.5MPa and 800h-1, the conversion of CO was 76.98 %, the selectivity of C5+ 88.36 %, the chain growth probability 0.86, and as to 15.0%Co0.4%Ru/γ-Al2O3, the conversion of CO was 67.15%, the selectivity of C5+ 84.41% and the chain growth probability 0.84.

scholarly journals Fischer-Tropsch synthesis using carbon dioxide, water and electricity

2021 ◽  
Author(s):  
Boon Siang Yeo ◽  
Yansong Zhou ◽  
Antonio Martín ◽  
Federico Dattila ◽  
Shibo Xi ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Energy Efficiency ◽  
Chain Growth ◽  
Renewable Electricity ◽  
Fischer Tropsch ◽  
New Era ◽  
Oxygenated Compounds ◽  
Ft Synthesis ◽  
Chain Growth Probability ◽  
Carbon Molecules

Abstract The Fischer-Tropsch (FT) synthesis of fuels from CO and H2 lies at the heart of the successful and mature Gas-to-Liquid technology; however its reliance on fossil resources comes with the burden of an undesirable carbon footprint. In contrast, the electroreduction of CO2 (CO2RR) powered by renewable electricity has the potential to produce the same type of fuels, but in a carbon-neutral fashion. To date, only ethylene and ethanol are attainable at reasonable efficiencies and exclusively on copper. Herein, we report that the oxygenated compounds of nickel can selectively electroreduce CO2 to C1 – C6 hydrocarbons with significant yields (Faradaic efficiencies of C3+ up to 6.5%). While metallic Ni only produces hydrogen and methane under CO2RR and FT conditions respectively, we show that polarized nickel (Niδ+) sites facilitate ambient CO2RR via the FT mechanism. The catalysts yield multi-carbon molecules with an unprecedented chain growth probability values (α) up to 0.44, which matches many technical FT synthesis systems. We anticipate that the integration of the herein proposed electrochemical-FT scheme with fuel cells may provide at this seminal stage up to 7% energy efficiency for C3+ hydrocarbons, inaugurating a new era towards the defossilization of the chemical industry.

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