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Title: Adsorption and ring-opening of lactide on the chiral metal surface Pt(321){sup S} studied by density functional theory

We study the adsorption and ring-opening of lactide on the naturally chiral metal surface Pt(321){sup S}. Lactide is a precursor for polylactic acid ring-opening polymerization, and Pt is a well known catalyst surface. We study, here, the energetics of the ring-opening of lactide on a surface that has a high density of kink atoms. These sites are expected to be present on a realistic Pt surface and show enhanced catalytic activity. The use of a naturally chiral surface also enables us to study potential chiral selectivity effects of the reaction at the same time. Using density functional theory with a functional that includes the van der Waals forces in a first-principles manner, we find modest adsorption energies of around 1.4 eV for the pristine molecule and different ring-opened states. The energy barrier to be overcome in the ring-opening reaction is found to be very small at 0.32 eV and 0.30 eV for LL- and its chiral partner DD-lactide, respectively. These energies are much smaller than the activation energy for a dehydrogenation reaction of 0.78 eV. Our results thus indicate that (a) ring-opening reactions of lactide on Pt(321) can be expected already at very low temperatures, and Pt might be amore » very effective catalyst for this reaction; (b) the ring-opening reaction rate shows noticeable enantioselectivity.« less
Authors:
;  [1]
  1. Department of Physics, Campus Plaine - CP 231, Universite Libre de Bruxelles, 1050 Brussels (Belgium)
Publication Date:
OSTI Identifier:
22416056
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACTIVATION ENERGY; ADSORPTION; ATOMS; CATALYSTS; CHIRALITY; DEHYDROGENATION; DENSITY FUNCTIONAL METHOD; DIFFUSION BARRIERS; EV RANGE; LACTATES; MOLECULES; PLATINUM SULFIDES; POLYMERIZATION; POTENTIALS; REACTION KINETICS; SURFACES; TEMPERATURE DEPENDENCE; VAN DER WAALS FORCES