A density functional theory study of HCN hydrogenation to methylamine on Co(111)

The hydrogenation of HCN to methylamine on Co(111) was used as a model reaction to study the hydrogenation of nitriles to primary amines. Density functional theory was used to characterize the reaction mechanism, and the results obtained were compared with those for the same reaction on Ni(111). Hyd...

Full description

Saved in:
Bibliographic Details
Published in:Journal of catalysis 2007-05, Vol.248 (1), p.38-45
Main Authors: Oliva, Carolina, van den Berg, Co, (Hans) Niemantsverdriet, J.W., Curulla-Ferré, Daniel
Format: Article
Language:English
Subjects:
Catalysis
Catalysts
Chemistry
Cobalt
DFT
Exact sciences and technology
General and physical chemistry
Hydrogen cyanide
Hydrogenation
Methylamine
Nickel
Nitriles
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The hydrogenation of HCN to methylamine on Co(111) was used as a model reaction to study the hydrogenation of nitriles to primary amines. Density functional theory was used to characterize the reaction mechanism, and the results obtained were compared with those for the same reaction on Ni(111). Hydrogen cyanide adsorbs more strongly on Co(111) than on Ni(111), with an adsorption energy of −1.72 eV. The hydrogenation product, methylamine, is weakly adsorbed on Co(111), with an adsorption energy of −0.53 eV, which is very similar to the adsorption energy calculated on Ni(111). The calculated adsorption energies were used to explain the differences in activity and selectivity observed between nickel- and cobalt-based catalysts; the stronger adsorption of HCN on cobalt explains both the lower activity and the higher selectivity observed on this metal. Regarding the reaction mechanism, the hydrogenation reaction implies an imine intermediate (H 2CNH) independent of whether hydrogen reacts with the carbon atom or with the nitrogen atom of the hydrogen cyanide molecule in the first step. The imine intermediate subsequently reacts to form H 3CNH, which is finally hydrogenated to yield methylamine. The overall surface reaction is endothermic. Remarkably, comparing the HCN hydrogenation reaction mechanism on Co(111) and Ni(111) revealed no significant differences.
ISSN:0021-9517
1090-2694
DOI:10.1016/j.jcat.2007.02.021