Adsorption of methyl acetoacetate at Ni{111}: experiment and theory

Ontaneda, J., Nicklin, R. E. J., Cornish, A., Roldan, A., Grau-Crespo, R. ORCID: https://orcid.org/0000-0001-8845-1719 and Held, G. (2016) Adsorption of methyl acetoacetate at Ni{111}: experiment and theory. Journal of Physical Chemistry C, 120 (48). pp. 27490-27499. ISSN 1932-7455 doi: 10.1021/acs.jpcc.6b10023

Abstract/Summary

The hydrogenation of methyl acetoacetate (MAA) over modified Ni catalysts is one of the most important and best studied reactions in heterogeneous enantioselective catalysis. Yet, very little molecular-level information is available on the adsorption complex of the reactant. Here we report on a combined experimental and theoretical study of MAA adsorption on Ni{111}. XPS shows that the chemisorbed layer is stable up to 250 K; above 250 K decomposition sets in. In ultra-high vacuum conditions, multilayers grow below 150 K. DFT modelling predicts a deprotonated enol species with bidentate coordination on the flat Ni{111} surface. The presence of adatoms on the surface leads to stronger MAA adsorption in comparison with the flat surface, whereby the stabilization energy is high enough for MAA to drive the formation of adatom defects at Ni{111}, assuming the adatoms come from steps. Comparison of experimental XPS and NEXAFS data with theoretical modeling, however, identify the bidentate deprotonated enol on the flat Ni{111} surface as the dominant species at 250 K, indicating that the formation of adatom adsorption complexes is kinetically hindered at low temperatures.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/68223
Identification Number/DOI	10.1021/acs.jpcc.6b10023
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Uncontrolled Keywords	methyl acetoacetate, Ni(111), density functional theory, x-ray photoelectron spectroscopy, NEXAFS
Publisher	American Chemical Society
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