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 cell uloses impregnated with various amounts of phosphoric acid. The influence o n the yields of levoglucosan and levoglucosenone was studied taking into ac count the supramolecular structure, degree of polymerization, hydrophilic p roperties 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 on ly in a narrow range of 75-85% regardless of the impregnation and pretreatm ent conditions of the celluloses. The maximum progress in cellulose dehydra tion reactions resulting in the highest levoglucosenone content of 78% is r eached with Munktell microcrystalline cellulose owing to its low accessibil ity and high ordered supramolecular structure. For pulps with a less ordere d cellulosic supramolecular structure, breaking of glycosidic bonds with th e formation of levoglucosan besides levoglucosenone occurred and the relati ve amount of non-dehydrated anhydrosaccharides increased. (C) 2001 Elsevier Science B.V. All rights reserved.