Kinetics of acid-catalysed delignification of Eucalyptus globulus wood by acetic acid

Summary The kinetics of HCl-catalysed delignification of Eucalyptus globulus wood by 70% (w/w) acetic acid solution were satisfactorily explained by a model in which 5% of the lignin fraction could not be eliminated and the remaining 95% was eliminated by a single process which, in view of the activation energy calculated from the data was attributed to the hydrolysis of -aryl ether bonds. The selectivity of the process was effectively independent of HCl concentration and operating temperature for pulp yields >50%. At high temperature (160 °C) and catalyst concentration (0.027 MHCl), lignin condensation and precipitation became significant and the data were better fitted by a model comprising two consecutive processes: lignin solubilization followed by lignin condensation.The authors are grateful to the CICYT for financial support of this work (Project AGF93-0605) and also to the DGICYT for a research grant awarded to J. González