Effect of individual organic components on the thermal decomposition and generation of monocycle aromatic hydrocarbons in the pyrolysis of cellulose/xylan/lignin mixtures

Abstract

The individual organic components of biomass, namely cellulose, xylan and lignin, are fundamental and essential factors for the generation of bio-based monocyclic aromatic hydrocarbons (MAHs) from the pyrolysis of lignocellulosic biomass. In this study, the influence of these individual components on the characteristics of the thermal decomposition and MAHs generation during the pyrolysis of cellulose/xylan/lignin mixtures was investigated using a TG-MS analyzer and a Py-GC/MS analyzer. The results show that an increase in both the contents of cellulose and xylan was conducive to the thermal decomposition of the cellulose/xylan/lignin mixtures, while an increase in the content of lignin had the opposite effect. The effect that the components had on the thermal decomposition followed the order cellulose > xylan > lignin. Benzene was released during the pyrolysis in the temperature range from 281 to 766 °C, and the amount released increased when the amount of cellulose, xylan, or lignin increased by various mechanisms. Toluene was released in the temperature range from 281 to 692 °C and the amount released only increased with an increase in the lignin content. Compared to linear heating (15 °C min⁻¹), fast pyrolysis (20 °C ms⁻¹) was conducive to the formation of xylene. MAHs were rarely directly produced during the pyrolysis of cellulose and xylan, but the presence of both the components was beneficial for promoting the MAHs yield. The promotion ratio due to an increase in cellulose content (86.13%) was higher than that caused by an increase in xylan content (30.73%).