Determining the influence of eucalypt lignin composition in paper pulp yield using Py-GC/MS

A set of Eucalyptus globulus woods from different origins and growth conditions, giving a wide range of pulp yields (from 40 to 60%) upon kraft cooking, was analyzed using Py-GC/MS. The carbohydrate-derived compounds and the compounds derived from syringyl (S) and guaiacyl (G) lignin units were analyzed and the lignin/carbohydrate and S/G ratios determined. Eucalypt woods giving higher pulp yield released higher amounts of S-type compounds upon Py-GC/MS. A significant correlation was observed between pulp yield and the lignin composition in terms of the S/G ratio. By contrast, the lignin/carbohydrate ratio obtained by Py-GC/MS did not show a significant correlation with the pulp yield. This indicates that the lignin composition is a more important parameter influencing pulp yield than the lignin content.