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The role of carbon deposits in the hydrogenation of C5 hydrocarbons

Paper ID Volume ID Publish Year Pages File Format Full-Text
43324 45964 2008 7 PDF Available
Title
The role of carbon deposits in the hydrogenation of C5 hydrocarbons
Abstract

The hydrogenation of pentenes, pentenenitriles and 1-pentyne has been studied over Al2O3-supported Ni and Pd catalysts. In particular the role of hydrocarbonaceous residues in such reactions has been probed. This has been achieved through the use of a tapered element oscillating microbalance to record mass changes in situ during the catalytic reactions with simultaneous analysis by gas chromatography. Sequential adsorption and reaction studies demonstrate that the influence exerted by hydrocarbonaceous deposits is critically dependent upon the compound from which they are derived, with deposits from different isomers of the same compound exhibiting different effects. In particular, in the case of 2-pentenes, a hydrocarbonaceous overlayer resulting from the hydrogenation of cis-2-pentene significantly activates Ni/Al2O3 towards hydrogenation of trans-2-pentene and vice versa. In the case of pentenenitrile hydrogenation however, trans-3-pentenenitrile deposits an overlayer which renders inactive the sites responsible for the selective hydrogenation of cis-2-pentenenitrile to pentanenitrile. Results from 1-pentyne hydrogenation studies over Pd/Al2O3 support previous conclusions regarding the development of a carbon-rich active phase. This work demonstrates the importance of the consideration of heterogeneous catalysts as dynamic materials which evolve during reaction and adds to the increasing awareness of the potential positive roles played by carbonaceous deposits in such reactions.

Graphical abstractThe deposition of hydrocarbonaceous material on heterogeneous catalysts is followed in situ during the hydrogenation of various C5 hydrocarbons by employing a tapered element oscillating microbalance (TEOM). Such overlayers are observed to play a crucial role in hydrogenation reactions, e.g. in the case of 2-pentenes a hydrocarbonaceous overlayer deposited during cis-2-pentene hydrogenation activates the catalyst towards trans-2-pentene hydrogenation and vice versa. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Adsorption; Hydrogenation; Microbalance; Alkenes; Alkynes
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The role of carbon deposits in the hydrogenation of C5 hydrocarbons
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 345, Issue 1, 31 July 2008, Pages 51–57
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
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Full-text PDF Download
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