Surface structural-chemical characterization of a single-site d^sup 0^ heterogeneous arene hydrogenation catalyst having 100% active sites

Structural characterization of the catalytically significant sites on solid catalyst surfaces is frequently tenuous because their fraction, among all sites, typically is quite low. Here we report the combined application of solid-state ...C-cross-polarization magic angle spinning nuclear magnetic re...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2013-01, Vol.110 (2), p.413
Main Authors: Williams, Linda A, Guo, Neng, Motta, Alessandro, Delferro, Massimiliano, Fragalà, Ignazio L, Miller, Jeffrey T, Marks, Tobin J
Format: Article
Language:English
Subjects:
Adsorption
Alumina
Catalysts
Electrostatics
Hydrocarbons
NMR
Nuclear magnetic resonance
Online Access:Get full text
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Summary:Structural characterization of the catalytically significant sites on solid catalyst surfaces is frequently tenuous because their fraction, among all sites, typically is quite low. Here we report the combined application of solid-state ...C-cross-polarization magic angle spinning nuclear magnetic resonance (...C-CPMAS-NMR) spectroscopy, density functional theory (DFT), and Zr X-ray absorption spectroscopy (XAS) to characterize the adsorption products and surface chemistry of the precatalysts (...)2ZrR2 (R = H, CH3) and ... adsorbed on Bronsted superacidic sulfated alumina (AlS). The latter complex is exceptionally active for benzene hydrogenation, with ~100% of the Zr sites catalytically significant as determined by kinetic poisoning experiments. The 13C-CPMAS-NMR, DFT, and XAS data indicate formation of organozirconium cations having a largely electrostatic ... AlS- interaction with greatly elongated Zr... AlS distances of ~2.35(2) A. The catalytic benzene hydrogenation cycle is stepwise understandable by DFT, and proceeds via turnover-limiting H2 delivery to surface ... AlS- species, observable by solid-state NMR and XAS. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:0027-8424
1091-6490