Effect of Liquid to Solid Ratio on Autohydrolysis of Eucalyptus globulus Wood Meal

Autohydrolysis of Eucalyptus globulus both with and without the addition of 5 g/L formic acid was explored for different liquid-to-solid (L/S) ratios at 150 oC for 100 min. The L/S ratio has an impact on the dissolution of wood components during prehydrolysis. The extraction yield of wood components other than lignin decreased with increasing L/S ratio, while lignin removal increased with increasing L/S ratio, irrespective of acid reinforcement. The molecular weight (Mw) of dissolved hemicelluloses and lignin remained relatively constant. The average degree of polymerization of hemicelluloses isolated from the hot water extract was between 7 and 8 over a L/S ratio range from 3:1 to 50:1. The cellulose to glucose conversion yield of pretreated wood samples improved during prehydrolysis with 5 g/L formic acid. Although the conversion yield of autohydrolyzed wood meal stayed relatively constant, the conversion yield of dilute acid-pretreated wood samples increased with increasing L/S ratio.