Analysis of pyrolysis behaviors of biomass extractives via non-linear stepwise heating program based on Gaussian multi-peak fitting of differential thermogravimetric curve

The thermal decomposition of extractives can yield additional products, resulting in a different final product distribution of bio-oil, especially for extractives-rich biomass. However, the thermal decompositon behavior of extractives themselves has long been ignored, but deserves deep investigation. Herein, the non-linear stepwise heating program based on Gaussian multi-peak fitting of differential thermogravimetric curve for biomass extractives was designed. Using this stepwise heating program, the pyrolysis process of different chemical substances in biomass extractives was effectively decoupled and systematically studied. As for water-soluble extractives, the evaporation of volatile substances, the thermal decomposition of water-soluble carbohydrates, phenolic substances, and nitrogenous substances proceed in sequence with the increase of temperature during the pyrolysis process. With regard to liposoluble extractives, the pyrolysis included the volatilization of endogenous substances and the thermal decomposition of different lipids into olefins. This work provides a systematic understanding of thermal decomposition process in the extractives of lignocellulosic biomass.