Effect of Torrefaction Pretreatment on Chemical Structure and Pyrolysis Behaviors of Cellulose

In order to obtain the effect of torrefaction pretreatment on chemical structure and pyrolysis reactivity of cellulose, torrefaction of cellulose was conducted in a fixed bed reactor at varying torrefaction temperature and residence time. The chemical composition and structural alterations of torrefied cellulose were characterized by elemental analyzer and Fourier-transform infrared spectroscopy (FTIR). The investigation on the pyrolysis behaviors of raw and torrefied cellulose were carried out by using a thermogravimetric analyzer (TGA). The results showed that torrefaction of cellulose mainly proceeded a series of deoxygenation, polycondensation and carbonization reactions. The severe carbonization of cellulose occurred when the torrefaction temperature and residence time were larger than 300 degrees C and 40 min, resulting in the drastic decrease in the pyrolysis reactivity of cellulose. Hence, the optimal torrefaction temperature should not exceed 280 degrees C.