Abstract: Depolymerized lignin products are very complex mixtures.In this paper,based on depolymerization solution of commercially available sodium lignosulfonate under mild conditions,an efficient method for separation and analysis of depolymerized lignin products and evaluation of the yields of reaction products has been developed.The GPC result indicated that lignosulfonate was almost completely converted into small molecules,which mainly dispersed in three oligomer ranges.9 of depolymerized aromatics products accounted for 30 wt% of depolymerized solution are identified by GC-MS.The study also indicated that under these mild conditions lignosulfonate was completely depolymerized,while its sulfonate functional groups were removed easily in situ to form salts,which were confirmed with SEM and EDS energy spectrum.Preliminary studies highlight that the secondary sulfo group (C_α-SO₃M) within real lignin help to promote alkyl aryl ether bond (β-O-4) cleavage,thus facilitated the lignin depolymerization reaction.Depolymerized products in high yields of more than 95 wt% were obtained.

Key words: lignosulfonate, acid-catalyzed depolymerization, products analysis, lignin-based aromatic compounds