In the context of climate change mitigation, CO2 methanation is an important option for the production of synthetic carbon-neutral fuels and for atmospheric CO2 recycling. While being highly exothermic, this reaction is kinetically unfavorable, requiring a catalyst to be efficiently activated. Recently Rh nanoparticles gained attention as effective photocatalyst, but the rate-determining step of this reaction on Rh surface has not been characterized yet. In this work, Density Functional Theory and Nudged Elastic Band calculations were performed to study the Rh-catalyzed rate-determining step of the CO2 methanation, which concerns the hydrogen assisted cleavage of the CO* molecule and subsequent formation of CH* and O* (* marks adsorbed species), passing through the CHO* key intermediate. The configurations of the various adsorbates on the Rh (100) surface were investigated and the reaction mechanism was studied exploiting different exchange-correlation functionals (PBE, RPBE) and the PBE+U technique. The methanation rate-determining step consists of two subprocesses which subsequently generate and dissociate the CHO* species. The energetics and the dynamics of such processes are extensively studied and described. Interestingly, PBE and PBE+U calculated activation barriers are in good agreement with the available experimental data, while RPBE largely overestimate the CHO* dissociation barrier.

Study of the Rate-Determining Step of Rh Catalyzed CO2 Reduction: Insight on the Hydrogen Assisted Molecular Dissociation / M. Vanzan, M. Marsili, S. Corni. - In: CATALYSTS. - ISSN 2073-4344. - 11:5(2021), pp. 538.1-538.18. [10.3390/catal11050538]

Study of the Rate-Determining Step of Rh Catalyzed CO2 Reduction: Insight on the Hydrogen Assisted Molecular Dissociation

M. Vanzan
Primo
;
2021

Abstract

In the context of climate change mitigation, CO2 methanation is an important option for the production of synthetic carbon-neutral fuels and for atmospheric CO2 recycling. While being highly exothermic, this reaction is kinetically unfavorable, requiring a catalyst to be efficiently activated. Recently Rh nanoparticles gained attention as effective photocatalyst, but the rate-determining step of this reaction on Rh surface has not been characterized yet. In this work, Density Functional Theory and Nudged Elastic Band calculations were performed to study the Rh-catalyzed rate-determining step of the CO2 methanation, which concerns the hydrogen assisted cleavage of the CO* molecule and subsequent formation of CH* and O* (* marks adsorbed species), passing through the CHO* key intermediate. The configurations of the various adsorbates on the Rh (100) surface were investigated and the reaction mechanism was studied exploiting different exchange-correlation functionals (PBE, RPBE) and the PBE+U technique. The methanation rate-determining step consists of two subprocesses which subsequently generate and dissociate the CHO* species. The energetics and the dynamics of such processes are extensively studied and described. Interestingly, PBE and PBE+U calculated activation barriers are in good agreement with the available experimental data, while RPBE largely overestimate the CHO* dissociation barrier.
CO2 methanation; CO2 reduction; Density Functional Theory; Energy barrier; Energy landscape; Nudged Elastic Band; Rate-determining step; Reaction energy; Rhodium catalysts
Settore CHIM/02 - Chimica Fisica
2021
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1071988
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