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Nanosized nickel Ziegler-type hydrogenation catalysts: The role of organoaluminum and proton-donating compounds in their formation and optimum catalysis

Paper ID Volume ID Publish Year Pages File Format Full-Text
39199 45812 2015 11 PDF Available
Title
Nanosized nickel Ziegler-type hydrogenation catalysts: The role of organoaluminum and proton-donating compounds in their formation and optimum catalysis
Abstract

•The Ni(acac)2-AlEt3 system is not active in alkenes hydrogenation without activator.•The nature and concentration of the activator determine TOF, TON values of catalyst.•Proton-donor compounds (H2O, ROH) and Lewis bases were used as activators.•The model of nickel nanoparticles structure has been specified.

Turnover frequency (TOF) and turnover number (TON) of such Ziegler-type catalysts based on Ni(acac)2·nН2О (n = 0, 0.5, 3.0) and AlEt3, at different Al/Ni molar ratios, have been determined during their examination as styrene hydrogenation catalysts. It is found that the amount of crystallization water effects on the TOF and TON values of the nickel catalysts and defines their dependence on the Al/Ni ratio. It is shown that optimum concentration of proton-donating compounds ensures high values of TOF and TON. The nature of nickel-containing nanoparticles was determined using high-resolution electron microscopy. The size of the nickel clusters depended on the water content of the nickel precursor. The average particle size increased from 1.2 to 2.3 nm on changing the precursor from Ni(acac)2·0.5Н2О to Ni(acac)2·3Н2О. It was shown that organoaluminum compounds acted as Ni(II) → Ni(0) reducing agents, nanoparticle stabilizers, and hydrogenation activity inhibitors. A nickel nanoparticle model is specified, one which explains the activating role of the proton-donating compounds in combination with the Al/Ni ratio.

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Keywords
Hydrogenation; Nickel catalysts; Triethylaluminum; Nanoparticle model
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Nanosized nickel Ziegler-type hydrogenation catalysts: The role of organoaluminum and proton-donating compounds in their formation and optimum catalysis
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 499, 25 June 2015, Pages 177–187
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
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Any Questions? feel free to contact us