A UBI-QEP Microkinetic Study for Fischer-Tropsch Synthesis on Iron Catalysts

Moqadam, Mahmoud; Rahmani, Mohammad; Karimi, Zohre; Naderifar, Abbas

doi:10.1016/j.proeng.2012.07.392

Cited by 8 publications

(4 citation statements)

References 25 publications

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“…Several models have been created in order to efficiently screen surfaces for their adsorption properties. The unity bond-index quadratic exponential potential method (UBI-QEP, formerly known as the bond-order conservation model), effective medium theory, and the Newns–Anderson model (on which the d-band model is based) are older models that are mainly used to rationalize trends or when many adsorption energies are needed, for example, as inputs to microkinetic models . Advances in density functional theory (DFT) have allowed relatively accurate calculations of adsorption energies in individual cases.…”

Section: Introductionmentioning

confidence: 99%

“…The unity bondindex quadratic exponential potential method (UBI-QEP, formerly known as the bond-order conservation model), 54 effective medium theory, 55 and the Newns−Anderson model 56 (on which the d-band model is based) are older models that are mainly used to rationalize trends or when many adsorption energies are needed, for example, as inputs to microkinetic models. 57 Advances in density functional theory (DFT) have allowed relatively accurate calculations of adsorption energies in individual cases. However, DFT is still too computationally expensive to allow the calculation of reaction networks on a large number of surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Site-Specific Scaling Relations for Hydrocarbon Adsorption on Hexagonal Transition Metal Surfaces

Montemore

Medlin

2013

J. Phys. Chem. C

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Screening a large number of surfaces for their catalytic performance remains a challenge, leading to the need for simple models to predict adsorption properties. To facilitate rapid prediction of hydrocarbon adsorption energies, scaling relations that allow for calculation of the adsorption energy of any intermediate attached to any symmetric site on any hexagonal metal surface through a carbon atom were developed. For input, these relations require only simple electronic properties of the surface and of the gas-phase reactant molecules. Determining adsorption energies consists of up to four steps: (i) calculating the adsorption energy of methyl in the top site using density functional theory or by simple relations based on the electronic structure of the surface; (ii) using modified versions of classical scaling relations to scale between methyl in the top site and C 1 species with more metal−surface bonds (i.e., C, CH, CH 2 ) in sites that complete adsorbate tetravalency; (iii) using gas-phase bond energies to predict adsorption energies of longer hydrocarbons (i.e., CR, CR 2 , CR 3 ); and (iv) expressing energetic changes upon translation of hydrocarbons to various sites in terms of the number of agostic interactions and the change in the number of carbon−metal bonds. Combining all of these relations allows accurate scaling over a wide range of adsorbates and surfaces, resulting in efficient screening of catalytic surfaces and a clear elucidation of adsorption trends. The relations are used to explain trends in methane reforming, hydrocarbon chain growth, and propane dehydrogenation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Site-Specific Scaling Relations for Hydrocarbon Adsorption on Hexagonal Transition Metal Surfaces

Montemore

Medlin

2013

J. Phys. Chem. C

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“…In addition Fij,exp is the observed value of i th response for j th experiment, whereas Fij,cal represents its calculated value of i th response for j th experiment [21]. Optimum parameters have been obtained by Genetic algorithms (GA).…”

Section: Parameter Estimationmentioning

confidence: 99%

A Comprehensive Kinetic Model of Fischer-Tropsch Synthesis over Supported Cobalt Catalyst

Jalilzadeh

Moqadam

2017

Preprint

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A comprehensive kinetic model of the Fischer-Tropsch synthesis (FTS) is developed in a fixed bed reactor under operating conditions (temperature, 230-235°C, pressure, 20-25 bar, gas hourly space velocity, 4000-5000 cm 3 (STP)/h/gcatalyst ,H2/CO feed molar ratio, 2.1) over a Co based catalyst. Reaction rate equations based on Eley-Rideal (ER) type model for initiation step and Langmuir-Hinshelwood-Hougen-Watson (LHHW) type model for propagation and termination steps of the FTS reactions have been considered and the readsorption of olefins were taken into account. The model that was reported in the literature was modified in order to explain many significant deviations from the ASF distribution. Optimum parameters have been obtained by Genetic Algorithms (GA). The calculated activation energies to produce n-paraffins and 1-olefins were in the range of 82.24 to 90.68 kJ/mol and 100.66 to 105.24 kJ/mol, respectively. The hydrocarbon distribution in FTS reactions was satisfactorily predicted particularly for paraffins.

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“…Single-Event MicroKinetic models have been developed for alkylation [30], hydrocracking [31], catalytic cracking [32] and reforming [33]. Specifically for FTS, studies using the SEMK modelling approach concentrate mostly on identifying the descriptors values corresponding to the catalysts used in a particular experimental investigation [34][35][36][37][38][39]. However less attention was dedicated to explain how a change in the catalyst properties and, hence, in the descriptor values, would influence the performances.…”

Section: Introductionmentioning

confidence: 99%

Unravelling the influence of catalyst properties on light olefin production via Fischer–Tropsch synthesis: A descriptor space investigation using Single-Event MicroKinetics

Chakkingal

Pirro

Cruz

et al. 2021

Chemical Engineering Journal

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A UBI-QEP Microkinetic Study for Fischer-Tropsch Synthesis on Iron Catalysts

Cited by 8 publications

References 25 publications

Site-Specific Scaling Relations for Hydrocarbon Adsorption on Hexagonal Transition Metal Surfaces

Site-Specific Scaling Relations for Hydrocarbon Adsorption on Hexagonal Transition Metal Surfaces

A Comprehensive Kinetic Model of Fischer-Tropsch Synthesis over Supported Cobalt Catalyst

Unravelling the influence of catalyst properties on light olefin production via Fischer–Tropsch synthesis: A descriptor space investigation using Single-Event MicroKinetics

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