Cellulose dehydration and depolymerization reactions during pyrolysis in the presence of phosphoric acid

The low-temperature pyrolysis process and dehydration reactions of cellulos e impregnated with phosphoric acid (1-10 wt.%) have been studied. Based on the yield of pyrolytic water and alterations of glucopyranose units of cell ulose, it has been confirmed that dehydrated cyclic structures are formed i n the solid phase during cellulose pyrolysis in the temperature interval 20 0-250 degrees C. Phosphoric acid also catalyzes the subsequent depolymeriza tion process of the dehydrated cellulose giving rise to 20% ton cellulose) of levoglucosenone. The yield of levoglucosenone depends on the amount of p hosphoric acid and the time of pyrolysis. Thus, the pathway of dehydration reactions can be controlled by variation of these two parameters. (C) 1999 Elsevier Science B.V. All rights reserved.