Volume 9, Issue 14 p. 2717-2726
Full Paper

Renewable Aromatics from Kraft Lignin with Molybdenum-Based Catalysts

Lisa Cattelan

Lisa Cattelan

Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney, Sydney, 2006 Australia

Department of Molecular Sciences and Nanosystems, Università Ca“ Foscari Venezia, Via Torino, 155- Venezia, Mestre, Italy

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Dr. Alexander K. L. Yuen

Dr. Alexander K. L. Yuen

Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney, Sydney, 2006 Australia

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Dr. Matthew Y. Lui

Dr. Matthew Y. Lui

Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney, Sydney, 2006 Australia

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Prof. Anthony F. Masters

Prof. Anthony F. Masters

Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney, Sydney, 2006 Australia

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Prof. Maurizio Selva

Prof. Maurizio Selva

Department of Molecular Sciences and Nanosystems, Università Ca“ Foscari Venezia, Via Torino, 155- Venezia, Mestre, Italy

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Prof. Alvise Perosa

Prof. Alvise Perosa

Department of Molecular Sciences and Nanosystems, Università Ca“ Foscari Venezia, Via Torino, 155- Venezia, Mestre, Italy

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Prof. Thomas Maschmeyer

Corresponding Author

Prof. Thomas Maschmeyer

Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney, Sydney, 2006 Australia

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First published: 30 March 2017
Citations: 29

Graphical Abstract

Molybdenum has the edge: Morphology-controlled molybdenum disulfide in supercritical ethanol is a highly effective catalyst for the depolymerization of Kraft lignin. Under similar conditions, molybdenum hemicarbide was particularly suited for the upgrading of Kraft lignin to aromatic chemicals.

Abstract

The catalytic depolymerization of Kraft lignin in supercritical ethanol was explored in the presence of Mo2C- and MoS2-based catalysts. At 280 °C, Mo2C and Mo2C/Al2O3 afforded aromatic yields of 425 and 419 mg g−1 lignin, respectively: amongst the highest yields reported to date. Ionic–liquid–assisted delamination of MoS2 resulted in highly active catalysts, capable of quantitative conversion of lignin at the expense of aromatic yield (approximately 186 mg g−1 lignin). Across all the catalysts studied, between 0.04 wt % and 0.38 wt % of molybdenum leached into the solution under supercritical conditions, according to inductively coupled plasma (ICP) analyses (corresponding to 27–570 μg of molybdenum in the reaction supernatant). A small contribution to the molybdenum in solution comes from the reactor itself (Hastelloy C contains 16 wt % Mo). Analysis of a depolymerization performed with fresh Kraft lignin and the soluble portion of the reaction mixture from a previous reactor run indicated that the leached species were neither active enough to afford the high conversions observed, nor selective enough to give high yields of aromatic products. In conjunction with the ICP data and differential chemoselectivities of the Mo2C- and MoS2-based catalysts, these results suggest that the bulk of the catalysis is heterogeneous.

Conflict of interest

The authors declare no conflict of interest.