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Influence on nickel particle size on the hydrodeoxygenation of phenol over Ni/SiO2

Paper ID Volume ID Publish Year Pages File Format Full-Text
53486 46972 2016 8 PDF Available
Title
Influence on nickel particle size on the hydrodeoxygenation of phenol over Ni/SiO2
Abstract

•Hydrodeoxygenation of phenol as model reaction for upgrading bio-oil.•Structure sensitivity over Ni/SiO2 elucidated by use of Ni particles of different particle size.•Small nickel particles favor deoxygenation and large particles favor hydrogenation.•Deoxygenation of cyclohexanol takes place on low coordinated Ni sites.

Hydrodeoxygenation (HDO) of phenol over nickel nano-particles of different size (5–22 nm) supported on SiO2 has been investigated in a batch reactor at 275 °C and 100 bar. Deoxygenation was only observed as a consecutive step of initial hydrogenation of phenol at the given conditions. Both the hydrogenation and deoxygenation reaction were found to be Ni-particle size dependent. Rapid hydrogenation of phenol to cyclohexanol was achieved over the catalysts with large particles, while the rate of deoxygenation of cyclohexanol was slow. For the catalysts with small Ni particles, the opposite behavior was observed Specifically, the turn over frequency (TOF) of hydrogenation was 85 times slower for 5 nm particles than for 22 nm particles. On the contrary, the TOF of cyclohexanol deoxygenation increased by a factor of 20 when decreasing the particle size from 20 nm to 5 nm. A simple kinetic model showed that the rate limiting step for phenol HDO shifted from deoxygenation to hydrogenation when the particle size was below 9–10 nm. Surface site population theory evidenced that the deoxygenation reactions were favored on step/corner sites, giving higher deoxygenation rates at small particles. For hydrogenation, the influence of particle size on the rate could be related to the size of the Ni facets with larger facets thus being better.

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Keywords
Bio-oil; Heterogeneous catalysis; Hydrodeoxygenation (HDO); Kinetics; Phenol; Structure sensitivity
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Influence on nickel particle size on the hydrodeoxygenation of phenol over Ni/SiO2
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 259, Part 2, 1 January 2016, Pages 277–284
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us