Issue 16, 2022

Complete utilization of waste lignin: preparation of lignin-derived carbon supports and conversion of lignin-derived guaiacol to nylon precursors

Abstract

The valorization of waste lignin for the production of high value-added chemicals is energetically and environmentally important. In this study, a new catalytic process was developed to produce raw materials for nylon production utilizing 100% of waste lignin emitted from industrial processes. Guaiacol, extracted from technical lignin, was converted to phenol through a hydrodeoxygenation reaction over carbon-supported MoO2 catalysts. The extracted lignin oil served as a carbon source to prepare lignin-derived porous carbons possessing an interconnected porous structure with a large pore size and volume via a nanocasting method. The high dispersion of MoO2 deposited on the porous carbon support enables a high guaiacol conversion (98.4%) and high phenol selectivity (73.7%) compared to those of a typical activated carbon support. The resulting phenol was selectively converted to cyclohexanone or cyclohexanol, depending on the controlled hydrogenation environments over carbon-supported Pd catalysts. The remaining solid residue during lignin extraction was also used as a carbon support to load Pd catalysts. The produced cyclohexanone and cyclohexanol were further converted to caprolactam and adipic acid, the main reagents used to produce nylon-6 and nylon-6,6 fibres, respectively. This process was demonstrated using real kraft and Klason lignin released from industry. The mass of guaiacol produced from 20 g of kraft lignin was 0.07 g, yielding either 0.032 g caprolactam or 0.043 g adipic acid, with a total yield of 0.15–0.25%. This study sheds light on utilizing waste lignin as a resource by producing not only guaiacol raw material for the production of high value-added nylon, but also a carbon support used for catalytic conversion.

Graphical abstract: Complete utilization of waste lignin: preparation of lignin-derived carbon supports and conversion of lignin-derived guaiacol to nylon precursors

Supplementary files

Article information

Article type
Paper
Submitted
18 Mar 2022
Accepted
19 May 2022
First published
31 May 2022

Catal. Sci. Technol., 2022,12, 5021-5031

Complete utilization of waste lignin: preparation of lignin-derived carbon supports and conversion of lignin-derived guaiacol to nylon precursors

J. G. Lee, S. Lee, H. Lee, J. F. Kurisingal, S. H. Han, Y. H. Kim and K. An, Catal. Sci. Technol., 2022, 12, 5021 DOI: 10.1039/D2CY00522K

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