Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study

Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study

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 C<sub>1</sub> + C<sub>1</sub> coupling reactio...

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Main Authors: Yanying Qi, Jia Yang, Anders Holmen, De Chen
Format: Article
Language:English
Published: MDPI AG 2019-06-01
Series:Catalysts
Subjects:
Fischer-Tropsch synthesis
chain growth
CO insertion
kinetic isotope effect
DFT
Online Access:https://www.mdpi.com/2073-4344/9/6/551
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spelling doaj-0fb3660ab9994e389b5194b19cb7a5ca2020-11-24T21:27:42ZengMDPI AGCatalysts2073-43442019-06-019655110.3390/catal9060551catal9060551Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope StudyYanying Qi0Jia Yang1Anders Holmen2De Chen3Department of Chemical Engineering, Norwegian University of Science and Technology, Sem Sælands vei 4, N-7491 Trondheim, NorwayDepartment of Chemical Engineering, Norwegian University of Science and Technology, Sem Sælands vei 4, N-7491 Trondheim, NorwayDepartment of Chemical Engineering, Norwegian University of Science and Technology, Sem Sælands vei 4, N-7491 Trondheim, NorwayDepartment of Chemical Engineering, Norwegian University of Science and Technology, Sem Sælands vei 4, N-7491 Trondheim, NorwayUnderstanding 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 C<sub>1</sub> + C<sub>1</sub> coupling reactions by theoretical calculations and kinetic isotope experiments. CH<sub>x(x=0&#8722;3)</sub>, 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 C<sub>1</sub> + C<sub>1</sub> coupling reactions are suggested to be energetically favorable because of the relative low reaction barriers. Moreover, five pathways are excluded where the C<sub>1</sub> 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 C<sub>1</sub> + C<sub>1</sub> coupling reaction is observed. The theoretical kinetic isotope effect of CO + CH<sub>2</sub> is inverse, which is consistent with the experimental observation. Thus, the CO + CH<sub>2</sub> pathway, owing to the relatively lower barrier, the high thermodynamic stability, and the inverse kinetic isotope effect, is suggested to be a favorable pathway.https://www.mdpi.com/2073-4344/9/6/551Fischer-Tropsch synthesischain growthCO insertionkinetic isotope effectDFT
collection DOAJ
language English
format Article
sources DOAJ
author Yanying Qi
Jia Yang
Anders Holmen
De Chen
spellingShingle Yanying Qi
Jia Yang
Anders Holmen
De Chen
Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study
Catalysts
Fischer-Tropsch synthesis
chain growth
CO insertion
kinetic isotope effect
DFT
author_facet Yanying Qi
Jia Yang
Anders Holmen
De Chen
author_sort Yanying Qi
title Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study
title_short Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study
title_full Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study
title_fullStr Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study
title_full_unstemmed Investigation of C<sub>1</sub> + C<sub>1</sub> Coupling Reactions in Cobalt-Catalyzed Fischer-Tropsch Synthesis by a Combined DFT and Kinetic Isotope Study
title_sort investigation of c<sub>1</sub> + c<sub>1</sub> coupling reactions in cobalt-catalyzed fischer-tropsch synthesis by a combined dft and kinetic isotope study
publisher MDPI AG
series Catalysts
issn 2073-4344
publishDate 2019-06-01
description 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 C<sub>1</sub> + C<sub>1</sub> coupling reactions by theoretical calculations and kinetic isotope experiments. CH<sub>x(x=0&#8722;3)</sub>, 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 C<sub>1</sub> + C<sub>1</sub> coupling reactions are suggested to be energetically favorable because of the relative low reaction barriers. Moreover, five pathways are excluded where the C<sub>1</sub> 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 C<sub>1</sub> + C<sub>1</sub> coupling reaction is observed. The theoretical kinetic isotope effect of CO + CH<sub>2</sub> is inverse, which is consistent with the experimental observation. Thus, the CO + CH<sub>2</sub> pathway, owing to the relatively lower barrier, the high thermodynamic stability, and the inverse kinetic isotope effect, is suggested to be a favorable pathway.
topic Fischer-Tropsch synthesis
chain growth
CO insertion
kinetic isotope effect
DFT
url https://www.mdpi.com/2073-4344/9/6/551
work_keys_str_mv AT yanyingqi investigationofcsub1subcsub1subcouplingreactionsincobaltcatalyzedfischertropschsynthesisbyacombineddftandkineticisotopestudy
AT jiayang investigationofcsub1subcsub1subcouplingreactionsincobaltcatalyzedfischertropschsynthesisbyacombineddftandkineticisotopestudy
AT andersholmen investigationofcsub1subcsub1subcouplingreactionsincobaltcatalyzedfischertropschsynthesisbyacombineddftandkineticisotopestudy
AT dechen investigationofcsub1subcsub1subcouplingreactionsincobaltcatalyzedfischertropschsynthesisbyacombineddftandkineticisotopestudy
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