Study on the Evolution Pattern of the Aromatics of Lignin during Hydrothermal Carbonization

Waste straw contains a large amount of lignin, and its resource utilization is not only in line with the national double carbon development strategy, but also to alleviate environmental pollution. Hydrothermal carbonization new thermochemical conversion technology, which has attracted much attention because it can directly transform containing waste raw materials high moisture content low energy density. To investigate physicochemical properties aromatization changes lignin hydrochar, hydrothermal experiments were carried out at 290 °C solid–liquid ratio 1:20 for 0.00, 0.25, 0.50, 1.00, 1.50, 2.00, 4.00, 8.00 h, respectively. The experimental results shows that increase combustion quality lignin. Physical chemical analysis time from 0 2 hydrochar increased 21.21% 26.02% HHV 20.01 MJ/Kg 26.32 MJ/Kg. When holding exceeded calorific value tended be stable. With time, FTIR XRD show free hydroxyl groups water-soluble easily combined intramolecular intermolecular hydrogen bonds, thus forming an ordered crystal arrangement. Subsequently, structure formed well-arranged long chain through strong bond network, ring process aromatization. Aromatic accumulated, wave peak intensified. Hydrochar particles became larger arranged order. At same surface functional group detection degree crystallization almost unchanged when h. morphology was observed by SEM as follows: reaction entered insulation stage, microsphere began aggregate then larger. reached growth rate microspheres noticeably slowed. Therefore, optimal fuel best performance