Selective Hydrogenation of Phenol Catalyzed by Palladium on High-Surface-Area Ceria at Room Temperature and Ambient Pressure

Journal Article · Tue Feb 17 23:00:00 EST 2015 · ACS Catalysis

DOI:https://doi.org/10.1021/cs502000j· OSTI ID:1287003

Nelson, Nicholas C. ^[1]; Manzano, J. Sebastián ^[1]; Sadow, Aaron D. ^[1]; Overbury, Steven H. ^[2]; Slowing, Igor I. ^[1]

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1. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Palladium supported on high-surface-area ceria effectively catalyzes the hydrogenation of phenol to cyclohexanone at atmospheric pressure and room temperature. Activation of H-2 at Pd sites and phenol at surface ceria sites was investigated by probing the redox properties of the catalyst and studying the mechanism of phenol adsorption. Temperature-programmed reduction and pulsed chemisorption were used to examine the effects of prereduction temperature on catalyst dispersion and reducibility. We observed a sharp effect of prereduction temperature on catalytic activity. This dependence is rationalized as a result of interactions between palladium and ceria, which under reducing conditions enhance palladium dispersion and create different types of environments around the Pd active sites and of encapsulation of the catalyst caused by support sintering at high temperatures. Moreover, temperature-programmed diffuse reflectance infrared Fourier transform spectroscopy revealed that phenol undergoes dissociative adsorption on ceria to yield cerium-bound phenoxy and water. Reduction of the chemisorbed phenoxy species decreases the number of proton-accepting sites on the surface of ceria and prevents further dissociative adsorption. Subsequent phenol binding proceeds through physisorption, which is a less active binding mode for reduction by hydrogen. Finally, high activity can be restored upon regeneration of proton acceptor sites via reoxidation/reduction of the catalyst.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1287003
• Journal Information: ACS Catalysis, Journal Name: ACS Catalysis Journal Issue: 4 Vol. 5; ISSN 2155-5435
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
AQUEOUS-MEDIA
CARBON-MONOXIDE OXIDATION
CO OXIDATION
CYCLOHEXA
GAS SHIFT REACTION
NOBLE-METAL CATALYSTS
SUPPORTED PD
THERMAL-STABILITY
dissociative adsorption
mesoporous ceria
metal-support interactions
phenol hydrogenation
redox-active support