Behavior characterization of lignosulfonate depolymerization products under acid-catalyzed conditions using gas chromatography–mass spectrometry

Depolymerized real lignin products are very complex mixtures. Comprehensive assessment of the decomposition efficiency and characterizing of depolymerized products still remain extremely challenging. In this study, based on depolymerization solution of commercially available sodium lignosulfonate under mild conditions, an improved method was well established for characterization of real lignin depolymerized products using GC–MS, which enabled the detection of main 37 lignin-based aromatic products. The effects of acid-catalyzed temperature, time and catalyst/lignin ratio on the depolymerization products were systematically investigated. The result revealed that ~ 25 wt% of lignosulfonate was depolymerized into lignin-derived aromatic products under optimized mild acid-catalyzed reaction conditions of 130 °C for 60 min with a catalyst/lignin ratio of 2.334. Most of the identified products were common commercial compounds, while the obtained bisphenols were potential compounds for new applications such as bio-based polymer building blocks. Preliminary studies also highlight that the depolymerization behavior seems to present selectivity to some extent during these specified acid-catalyzed reaction.