Thermochemical conversion of lignocellulosic bio-waste via fast pyrolysis in molten salts

Abstract This study, for the first time, investigated the volatiles emission and thermochemical conversion mechanism of bio-waste during pyrolysis in molten salts (NaNO3-KNO3-NaNO2) at 300 °C. Cations of molten salts acted as catalysts while anions participated in the pyrolysis reaction. Compared with salt-free pyrolysis, more bio-waste was decomposed in molten salts, to produce more than 14 times the mass of gaseous products and twice the mass of liquid products. Furthermore, the thermochemical conversion behavior of typical biomass constituents, i.e. cellulose, hemicellulose and lignin, was also distinguished. The results suggested that lignin was most easily pyrolyzed to form numerous liquid acids, some nitrated aromatic compounds and more CO, H2. In contrast, the decomposition of cellulose was certainly restricted while more significant effects of anions were found in hemicellulose cracking by generating nitrogen-containing heterocyclic rings and amines. Besides, interactions among different biomass constituents were confirmed to affect the generation of bio-waste pyrolysis products.