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Mechanism of Selective Hydrogenation of α,β-Unsaturated Aldehydes on Silver Catalysts: A Density Functional Study

Kim, Kok Hwa and Mohammad, Amjad B. and Yudanov, Ilya V. and Neyman, Konstantin M. and Bron, Michael and Claus, Peter and Rösch, Notker (2009):
Mechanism of Selective Hydrogenation of α,β-Unsaturated Aldehydes on Silver Catalysts: A Density Functional Study.
In: The Journal of Physical Chemistry C, pp. 13231-13240, 113, (30), [Online-Edition: http://dx.doi.org/10.1021/jp902078c],
[Article]

Abstract

Supported silver catalysts exhibit a remarkably high selectivity in the industrially important hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols. We carried out density functional calculations to clarify factors that affect the catalytic function of silver in hydrogenating unsaturated aldehydes. We examined the activity and the selectivity of model silver catalysts for acrolein, the simplest, yet most difficult unsaturated aldehyde to be selectively hydrogenated. We focused on describing bulky catalyst particles, represented by sites on extended silver surfaces, on the regular clean Ag(110) surface and the surface Osub/Ag(111) with subsurface oxygen centers. On Ag(110) our results imply propanal, the undesired saturated aldehyde, to be the main product. In contrast, the calculations suggest a very high selectivity of Osub/Ag(111) for the corresponding unsaturated alcohol, allyl alcohol, although the activity of this system is lower than that of clean silver. At variance with Pt(111), where the selectivity to allyl alcohol is strongly reduced by the hindered desorption of the latter, allyl alcohol and propanal products are predicted to desorb easily from both Ag(110) and Osub/Ag(111) at common reaction temperatures. We also analyzed inherent limitations for an accurate description of the chemical regioselectivity by contemporary computational methods.

Item Type: Article
Erschienen: 2009
Creators: Kim, Kok Hwa and Mohammad, Amjad B. and Yudanov, Ilya V. and Neyman, Konstantin M. and Bron, Michael and Claus, Peter and Rösch, Notker
Title: Mechanism of Selective Hydrogenation of α,β-Unsaturated Aldehydes on Silver Catalysts: A Density Functional Study
Language: English
Abstract:

Supported silver catalysts exhibit a remarkably high selectivity in the industrially important hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols. We carried out density functional calculations to clarify factors that affect the catalytic function of silver in hydrogenating unsaturated aldehydes. We examined the activity and the selectivity of model silver catalysts for acrolein, the simplest, yet most difficult unsaturated aldehyde to be selectively hydrogenated. We focused on describing bulky catalyst particles, represented by sites on extended silver surfaces, on the regular clean Ag(110) surface and the surface Osub/Ag(111) with subsurface oxygen centers. On Ag(110) our results imply propanal, the undesired saturated aldehyde, to be the main product. In contrast, the calculations suggest a very high selectivity of Osub/Ag(111) for the corresponding unsaturated alcohol, allyl alcohol, although the activity of this system is lower than that of clean silver. At variance with Pt(111), where the selectivity to allyl alcohol is strongly reduced by the hindered desorption of the latter, allyl alcohol and propanal products are predicted to desorb easily from both Ag(110) and Osub/Ag(111) at common reaction temperatures. We also analyzed inherent limitations for an accurate description of the chemical regioselectivity by contemporary computational methods.

Journal or Publication Title: The Journal of Physical Chemistry C
Volume: 113
Number: 30
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Fachgebiet Technische Chemie > Technische Chemie II
07 Department of Chemistry > Fachgebiet Technische Chemie
Date Deposited: 20 Jul 2009 10:06
Official URL: http://dx.doi.org/10.1021/jp902078c
Additional Information:

Publication Date (Web): 7. Juli 2009

Identification Number: doi:10.1021/jp902078c
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