This work provides an assessment on the fractionation of Eucalyptus globulus, wood by sequential stages of autohydrolysis (to cause the solubilization of hemicelluloses) and organosolv pulping (to dissolve lignin, leaving solids enriched in cellulose). With this approach, valuable products (hemicellulose-derived saccharides, sulphur-free lignin fragments and cellulosic substrates with low contents of residual hemicelluloses) are obtained in separate streams, according to the biomass refinery approach. Autohydrolysis was carried out under optimized operational conditions, and the organosolv pulping step was performed using uncatalyzed ethanol-water solutions. The effects of the most influential operational variables (autohydrolysis severity, delignification temperature and ethanol concentration in the organosolv stage) on solid yield, solid composition, cellulose susceptibility and recovery of the various fractions was assessed using statistical method, which enabled the identification of the most favourable operational conditions. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Page 2 of 29 Abstract: This work provides an assessment on the fractionation of Eucalyptus globulus, wood by sequential stages of autohydrolysis (to cause the solubilization of hemicelluloses) and organosolv pulping (to dissolve lignin, leaving solids enriched in cellulose). With this approach, valuable products (hemicellulose-derived saccharides, sulphur-free lignin fragments and cellulosic substrates with low contents of residual hemicelluloses) are obtained in separate streams, according to the biomass refinery approach. Autohydrolysis was carried out under optimized operational conditions, and the organosolv pulping step was performed using uncatalyzed ethanol-water solutions. The effects of the most influential operational variables (autohydrolysis severity, delignification temperature and ethanol concentration in the organosolv stage) on solid yield, solid composition, cellulose susceptibility and recovery of the various fractions was assessed using statistical method, which enabled the identification of the most favourable operational conditions.

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The influence of the process conditions of pulping of a trihybrid clone Paulownia on pulp properties for the soda anthraquinone process has been investigated in a semi-pilot scale. A composite central experimental design and a multiple regression were used to find the relationship between independent process variables and pulp properties. The ash content (0.89%) is lower and cellulose content (44.0%) is higher than those found for other species of Pauwlonia and other energetic crops. The elemental composition has a low content in S and N (0.21%) in comparation with poplar or willow. With a gross heating value of 20335 J/g, Paulownia is a suitable feedstock for use as solid biofuel. This is somewhat higher than those for hardwood, slightly higher than those for Pinus pinaster and softwood, and much higher than those for residues of food plants and agricultural crops. This supports the use of the genus Paulownia as an energy crop. The soda-anthraquinone pulping could be and adequate process for Paulownia. Fibre length (0.97 mm) is similar to hardwoods and suitable physical characteristics of paper sheets (tensile index) and acceptable chemical characteristics and yield pulping could be obtained by operating at lowintermediate temperature (163-171ºC) and alkali concentration (20%) and high or medium values for operation time (120-150 min). The pulp obtained at these conditions has suitable chemical (pulp) and physical (paper sheets) characteristics: yield (47.0%), ethanol-benzene extractives (2.22%), holocellulose contents (96.0%), α-cellulose contents (75.8%), lignin contents (8.28%), Shopper Riegler degree (23.2 ºSR), and tensile index (36.0) kN m/kg. HighlightsThe influences of the process conditions of pulping of a trihybrid clone Paulownia on pulp properties for the soda anthraquinone process have been investigated in a semi-pilot scale.The soda-anthraquinone pulping could be and adequate process for trihybrid clone Paulownia is similar to hardwoods and suitable physical characteristics of paper sheets.Trihybrid clone Paulownia is a suitable feedstock for use as solid biofuel.

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