Effect of metal salts impregnation and microwave-assisted solvent pretreatment on selectivity of levoglucosenone and levoglucosan from vacuum pyrolysis of ashe juniper waste

Levoglucosenone (LGO), furfural (FF) and levoglucosan are high value-added chemical components of bio-oil derived by thermal deconstruction of biomass. However, separation of these chemicals from bio-oil is challenging due to low selectivity. Impregnation of metal salts for catalytic pyrolysis or microwave treatment for altering chemical composition in biomass are potential methods to enhance selectivity of these high value-added chemicals. In the current study, Ashe juniper waste was pretreated with metal salts prior to vacuum pyrolysis and investigated the effects of metal salt type and its concentration on product yield and properties. The results showed that Levoglucosenone, which was attributed to dehydration of levoglucosan, was obtained only with the biomass pretreated with CuSO4 and ZnSO4. Metal salt type and concentration also affected the selectivity of levoglucosenone (LGO) and furfural (FF) by catalytic vacuum pyrolysis. Microwave-assisted organosolv treatment also affected biomass chemical composition, pyrolysis characteristics and promoted the selectivity of levoglucosan.