Accepted 2016 02 21 Chem Eng J -revised final version.pdf (1006.05 kB)

Insights into the mechanism of Nitrobenzene reduction to aniline over Pt catalyst and the significance of the adsorption of phenyl group on kinetics

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journal contribution
posted on 10.03.2016 by Tian Sheng, Yi-Jun Qi, Xiao Lin, Peijun Hu, Shi-Gang Sun, Wen-Feng Lin
Aniline (C6H5NH2) plays a significant role in both industry and daily life, and can be synthesized via catalytic hydrogenation of nitrobenzene (C6H5NO2) over transition metals; however fundamental investigations on reaction mechanisms in the heterogeneous catalysis are still lacking. In this work, the nitrobenzene reduction reaction over the Pt(111) model catalyst was studied using density functional theory (DFT) with the inclusion of van der Waals interaction, for fundamentally understanding the mechanisms at atomic and molecular levels. It was found that the double H-induced dissociation of N-O bond was the preferential path for the activation of nitro group, having a much lower reaction barrier than that of the direct dissociation and single H-induced dissociation paths. The overall mechanisms have been identified as: C6H5NO2* → C6H5NOOH* → C6H5N(OH)2* → C6H5NOH* → C6H5NHOH* → C6H5NH* → C6H5NH2*. The overall barrier of the nitro group reduction was calculated to be 0.75 eV, which is much lower than that of the benzene reduction (1.08 eV). Our DFT data elucidates clearly the reason why the major product of nitrobenzene reduction reaction was aniline. Furthermore, the adsorption/desorption of phenyl group was found to have significant impacts on kinetic barriers. Generally, in the hydrogenation process (N-H or O-H bond association), the phenyl group preferred to adsorb on the surface; but in the dissociation process (N-O bond dissociation) it preferred to desorb transiently at the transition state and to adsorb again when the dissociation was completed. This study also provides a solid theoretical insight into the selective catalysis of the large aromatic compounds.

Funding

Financial support from the EPSRC (EP/I013229/1), as part of the RCUK Energy Programme, and the NSFC (21361140374 and 21321062) is acknowledged.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Chemical Engineering

Published in

Chem. Eng. J.

Citation

SHENG, T. ...et al., 2016. Insights into the mechanism of Nitrobenzene reduction to aniline over Pt catalyst and the significance of the adsorption of phenyl group on kinetics. Chemical Engineering Journal, 293, pp. 337–344.

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2016

Notes

This paper was accepted for publication in the journal Chemical Engineering Journal and the definitive published version is available at http://dx.doi.org/10.1016/j.cej.2016.02.066

ISSN

1385-8947

Language

en

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