Influence of partial components removal on pyrolysis behavior of lignocellulosic biowaste in molten salts

Using molten NaNO3–KNO3–NaNO2 for biowaste pyrolysis provides a promising way to synergize the utilization of biowaste and fluctuating solar energy. However, the diversity of lignocellulosic biowaste and violent decomposition complicated the interactions between natural constituents. In this study, the pyrolysis behavior of woody and agricultural herbaceous lignocellulosic biowaste in molten salts was comprehensively investigated at 300 °C. Through the selective removal of partial hemicellulose or lignin, the specific role of the original structure on the products formation characteristics was further estimated. The results showed that more volatiles were released from the hemicellulose-enriched agricultural herbaceous biowaste than cellulose-enriched woody biowaste. The yields of water and organic liquids from hemicellulose or lignin removal were higher than that of raw biowaste. Specifically, hemicellulose dominated the generation of nitrogenous substances in the liquid products. As for the gas product, its yield from the hemicellulose removal sample was higher than raw biowaste but it decreased after removing lignin. Lignin was the primary contributor to the combustible CO, H2, and CH4, while the production of CO2 was more affected by hemicellulose. The lignin would compete with hemicellulose and be superior to the latter in the reaction with molten salt.