Utilization of Waste Lignin for Conversion to Carbon Supports and Nylon Precursors

Abstract

The valorization of waste lignin for the production of high value-added chemicals is energetically and environmentally important. Here, a new catalytic process was developed to produce raw materials for nylon production utilizing 100% of the 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 and the remaining solid residue were used as a carbon support to prepare supported catalysts. The produced phenol was selectively converted to cyclohexanone or cyclohexanol, over carbon-supported 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 fibers, respectively. This process was demonstrated using real kraft and Klason lignin released from industry. This study shed light to utilize waste lignin as a resource by producing not only guaiacol raw material for the production of high value-added nylon, but also the carbon support used for catalytic conversion.