Volatile products of catalytic flash pyrolysis of celluloses

Analytical pyrolysis combined with gas chromatography (Py-GC) has been used to study the composition of volatile products of different commercial celluloses impregnated with various amounts of phosphoric acid. The influence on the yields of levoglucosan and levoglucosenone was studied taking into account the supramolecular structure, degree of polymerization, hydrophilic properties and pretreatment conditions of the celluloses. It was found that levoglucosenone predominates in the volatiles of acid catalyzed pyrolysis. However, the relative total amount of both 1,6-anhydrosaccharides varied only in a narrow range of 75-85% regardless of the impregnation and pretreatment conditions of the celluloses. The maximum progress in cellulose dehydration reactions resulting in the highest levoglucosenone content of 78% is reached with Munktell microcrystalline cellulose owing to its low accessibility and high ordered supramolecular structure. For pulps with a less ordered cellulosic supramolecular structure, breaking of glycosidic bonds with the formation of levoglucosan besides levoglucosenone occurred and the relative amount of non-dehydrated anhydrosaccharides increased. (C) 2001 Elsevier Science B.V. All rights reserved.