Jump to main content
Jump to site search


Theoretical Understandings on the Selectivity of Acrolein Hydrogenation over Silver Surfaces: Non-Horiuti-Polanyi Mechanism is the Key

Abstract

Chemoselective hydrogenation of α, β-unsaturated aldehydes to unsaturated alcohols is not only an important reaction in the chemical industry but also a good model system to understand the catalytic selectivity in heterogeneous catalysis. In the current work, the selectivity of partial hydrogenation of acrolein (C3H4O), the simplest α, β-unsaturated aldehyde, is investigated employing density functional theory (DFT) calculations. Two hydrogenation mechanisms, namely the Horiuti-Polanyi mechanism and the non-Horiuti-Polanyi mechanism, are employed to study the partial hydrogenation of acrolein over Ag(111), Ag(100), Ag(211) and Ag(111)-mono surfaces. It is found that the hydrogenation of C3H4O to C3H5O at the terminal carbon and oxygen atom follows the non-Horiuti-Polanyi mechanism that C3H4O reacts with hydrogen molecules directly over all the silver surfaces studied, whilst atomic hydrogen is the active hydrogen species for the hydrogenation of C3H5O to C3H6O. Subsequently, the selectivities between partial hydrogenation products, i.e. propenol, propanal and enol, over silver surfaces with different morphologies are compared by calculating the energy difference between the rate-determining transition states. We find that the selectivity of propenol formation is increasing with the coordination number of surface silver atoms, which is in good agreement with the trend of selectivities obtained experimentally. It is also interesting to find that the selectivity trend obtained based solely upon the Horiuti-Polanyi mechanism for the hydrogenation of C3H4O to C3H5O and C3H5O to C3H6O cannot explain the experimental results. In other words, the non-Horiuti-Polanyi mechanism is able to give more reasonable explanation on the selectivity trend observed experimentally than the normally used Horiuti-Polanyi mechanism in heterogeneous catalysis. Our work highlights the significance of the non-Horiuti-Polanyi mechanism in understanding heterogeneous catalytic hydrogenation reactions.

Back to tab navigation

Supplementary files

Publication details

The article was received on 25 Jul 2017, accepted on 10 Aug 2017 and first published on 11 Aug 2017


Article type: Paper
DOI: 10.1039/C7CY01500C
Citation: Catal. Sci. Technol., 2017, Accepted Manuscript
  •   Request permissions

    Theoretical Understandings on the Selectivity of Acrolein Hydrogenation over Silver Surfaces: Non-Horiuti-Polanyi Mechanism is the Key

    K. Wang and B. Yang, Catal. Sci. Technol., 2017, Accepted Manuscript , DOI: 10.1039/C7CY01500C

Search articles by author

Spotlight

Advertisements