Lourenço, AnaGominho, JorgeV Marques, APereira, Helena2015-09-082015-09-082012-11LOURENÇO, A.; [et al] – Reactivity of syringyl and guaiacyl lignin units and delignification kinetics in the kraft pulping of eucalyptus globulus wood using Py-Gc-Ms/FID. Bioresource Technology. ISSN: 0960-8524. Vol. 123 (2012), pp. 296-3020960-8524http://hdl.handle.net/10400.21/5120Eucalyptus globulus sapwood and heartwood showed no differences in lignin content (23.0% vs. 23.7%) and composition: syringyl-lignin (17.9% vs. 18.0%) and guaiacyl-lignin (4.8% vs. 5.2%). Delignification kinetics of S- and G-units in heartwood and sapwood was investigated by Py-GC–MS/FID at 130, 150 and 170 °C and modeled as double first-order reactions. Reactivity differences between S and G-units were small during the main pulping phase and the higher reactivity of S over G units was better expressed in the later pulping stage. The residual lignin composition in pulps was different from wood or from samples in the initial delignification stages, with more G and H-units. S/G ratio ranged from 3 to 4.5 when pulp residual lignin was higher than 10%, decreasing rapidly to less than 1. The S/H was initially around 20 (until 15% residual lignin), decreasing to 4 when residual lignin was about 3%.engEucalyptus GlobulusLignin CompositionS/G RatioPyrolysisDelignificationjournal article10.1016/j.biortech.2012.07.092