THERMOMECHANOCHEMICAL PRETREATMENT OF WOOD IN A PROCESS-DEVELOPMENT UNIT

Continuous thermo-mechano-chemical pretreatment of wood (particle size: 0.25-0.50 mm) was conducted by steam injection for rapid heating-up of slurry (170-215-degrees-C), flow through homogenization valves (mechanical effects), and autohydrolysis in a plug flow reactor (90-95 s) (thermochemical reactions). The process was carried out in aqueous phase without addition of any chemicals. Residues resulting from the pretreatment were characterized by thermal and elemental analyses. The extent and selectivity (hemicellulose removal and delignification) of the wood solubilization were analyzed as a function of pretreatment temperature and the thermal severity factor, the goal being the optimization of hemicellulose dissolution. Experimental results were compared with those previously obtained in a batch cascade reactor system.