TY - JOUR
T1 - Unraveling the synergy between gold nanoparticles and chromium- hydrotalcites in aerobic oxidation of alcohols
AU - Liu, P.
AU - Degirmenci, V.
AU - Hensen, E.J.M.
PY - 2014/5
Y1 - 2014/5
N2 - The combination of gold nanoparticles (AuNPs) with chromium-substituted hydrotalcite (Cr-HT) supports makes very efficient heterogeneous catalysts (Au/Cr-HT) for aerobic alcohol oxidation under soluble-base-free conditions. The Au-support synergy increases with increasing Cr content of the support and decreasing AuNP size. In situ UV-Raman, X-ray absorption and photoelectron spectroscopic studies firmly establish that the strong Au-Cr synergy is related to a Cr ↔ Cr redox cycle at the Au/Cr-HT interface, where O activation takes place accompanied by electron transfer from Cr-HT to Au. The interfacial Cr species can be reduced by surface Au-H hydride and negative-charged Au species to close the catalytic cycle. A study of kinetic isotope effect indicates that alcohol O-H cleavage is facilitated by the presence of Cr, making a-C-H bond cleavage step more rate-controlling. Accordingly, a dual synergistic effect of Au/Cr-HT catalysts on the activation of O2 and alcohol reactants is proposed.
AB - The combination of gold nanoparticles (AuNPs) with chromium-substituted hydrotalcite (Cr-HT) supports makes very efficient heterogeneous catalysts (Au/Cr-HT) for aerobic alcohol oxidation under soluble-base-free conditions. The Au-support synergy increases with increasing Cr content of the support and decreasing AuNP size. In situ UV-Raman, X-ray absorption and photoelectron spectroscopic studies firmly establish that the strong Au-Cr synergy is related to a Cr ↔ Cr redox cycle at the Au/Cr-HT interface, where O activation takes place accompanied by electron transfer from Cr-HT to Au. The interfacial Cr species can be reduced by surface Au-H hydride and negative-charged Au species to close the catalytic cycle. A study of kinetic isotope effect indicates that alcohol O-H cleavage is facilitated by the presence of Cr, making a-C-H bond cleavage step more rate-controlling. Accordingly, a dual synergistic effect of Au/Cr-HT catalysts on the activation of O2 and alcohol reactants is proposed.
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897443351&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2014.03.001
DO - 10.1016/j.jcat.2014.03.001
M3 - Article
AN - SCOPUS:84897443351
SN - 0021-9517
VL - 313
SP - 80
EP - 91
JO - Journal of Catalysis
JF - Journal of Catalysis
ER -