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Microwave-assisted depolymerisation of organosolv lignin via mild hydrogen-free hydrogenolysis: Catalyst screening

Paper ID Volume ID Publish Year Pages File Format Full-Text
45306 46409 2014 13 PDF Available
Title
Microwave-assisted depolymerisation of organosolv lignin via mild hydrogen-free hydrogenolysis: Catalyst screening
Abstract

Lignin depolymerisation to simple aromatics was investigated by using a mild microwave-assisted approach. The reaction was catalysed by different supported metal nanoparticles on mesoporous Al-SBA-15 including -nickel (2, 5 and 10 wt.%), palladium (2 wt.%), platinum (2 wt.%) and ruthenium (2 wt.%). Three main products were indentified in the proposed lignin valorisation protocol, namely a bio-oil, a bio-char and a fraction of residual lignin. These have been characterised by means of several techniques including GC–MS, MALDI-TOF, HPSEC and elemental analysis in order to evaluate the extension and mechanism of the selected depolymerisation approach. In this work, the objective has been the maximisation of bio-oil yield as well as its content in phenolic monomeric compounds. All tested catalysts exhibited improved results as compared to the blank depolymerisation (without catalyst), demonstrating a synergetic effect of metal nanoparticles in lignin hydrogenolysis. The most abundant phenolic products observed in most studied catalysts have been solvent derived products such as diethyl phthalate and butyl-octyl phthalate ester. Interestingly, phenolic compounds derived from lignin were also obtained including mesitol and syringaldehyde as well as desaspidinol and aspidinol, depending on the utilised solvent in the systems. The bio-oil obtained was primarily composed of monomers, dimers and trimers. Biochar yield was relatively high in most cases (>35% in some cases) due to existing oligomerisation reactions under the investigated conditions except for the case of the use of formic acid which gave no biochar in the process. Residual lignin content was often high and repolymerisation was observed in some cases. The catalyst containing 10 wt.% nickel was confirmed to achieve the highest lignin depolymerisation degree, with a maximum yield of 30% bio-oil after a short time of reaction (typically 30 min of microwave irradiation).

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A mild hydrogenolytic microwave protocol using a Ni heterogeneous catalyst. ► Tetralin and formic acid as efficient hydrogen donating solvents. ► Production of simple aromatics including desaspidinol, syringaldehyde and syringol. ► Efficient lignin depolymerisation and bio-oil production with Ni10%Al-SBA-15.

Keywords
Organosolv lignin; Hydrogenolysis; Lignin depolymerisation; Heterogeneous catalysis
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Microwave-assisted depolymerisation of organosolv lignin via mild hydrogen-free hydrogenolysis: Catalyst screening
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 145, February 2014, Pages 43–55
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