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Shaped Ceria Nanocrystals Catalyze Efficient and Selective Para-Hydrogen-Enhanced Polarization.

Accepted version
Peer-reviewed

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Type

Article

Change log

Authors

Zhao, Evan W 
Zheng, Haibin 
Zhou, Ronghui 
Hagelin-Weaver, Helena E 
Bowers, Clifford R 

Abstract

Intense para-hydrogen-enhanced NMR signals are observed in the hydrogenation of propene and propyne over ceria nanocubes, nano-octahedra, and nanorods. The well-defined ceria shapes, synthesized by a hydrothermal method, expose different crystalline facets with various oxygen vacancy densities, which are known to play a role in hydrogenation and oxidation catalysis. While the catalytic activity of the hydrogenation of propene over ceria is strongly facet-dependent, the pairwise selectivity is low (2.4% at 375 °C), which is consistent with stepwise H atom transfer, and it is the same for all three nanocrystal shapes. Selective semi-hydrogenation of propyne over ceria nanocubes yields hyperpolarized propene with a similar pairwise selectivity of (2.7% at 300 °C), indicating product formation predominantly by a non-pairwise addition. Ceria is also shown to be an efficient pairwise replacement catalyst for propene.

Description

Keywords

NMR spectroscopy, catalysis, ceria, hydrogenation, nuclear spin hyperpolarization

Journal Title

Angew Chem Int Ed Engl

Conference Name

Journal ISSN

1433-7851
1521-3773

Volume Title

54

Publisher

Wiley

Rights

All rights reserved
Sponsorship
ACS‐PRF. Grant Number: 52258‐ND5 NSF. Grant Number: CHE‐1507230