Catalytic effects of four metal chlorides on fast pyrolysis of cellulose (I) Py-GC/MS experiments

Cellulose was pretreated by impregnation of four metal chlorides(KCl,CaCl2,FeCl3 and ZnCl2),and then subjected to fast pyrolysis by using pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS).The pyrolysis products were on-line analyzed to reveal the catalytic effects of the four metal chlorides.The results indicated that the presence of metal chlorides reduced the pyrolysis temperature of cellulose.Moreover,the impregnation of CaCl2 and FeCl3 inhibited the devolatilization of cellulose considerably,while this was not the case for the impregnation of KCl and ZnCl2.Fast pyrolysis of pure cellulose produced abundant levoglucosan,some furans as well as light carbonyl compounds,mainly including hydroxyacetaldehyde.After the impregnation of metal chlorides,the formation of levoglucosan was deeply inhibited.KCl and CaCl2 mainly promoted the depolymerization and dehydration of cellulose toform furans,and the pyrolytic ring scission to form various linear carbonyls and acids.FeCl3 and ZnCl2 mainly promoted the depolymerization and dehydration of cellulose to form anhydrosugars and furans.