Hydrolytic cleavage of lignin derived C-O bonds by acid/base catalysis in water

Dynamics of lignocellulose degradation by acid: Kinetic insights into high-solid acid pretreatment at normal temperatures

Conventional acid pretreatment at high temperatures (>100 °C) and low solid-liquid ratios, often leads to excessive inhibitor formation. In this study, a high-solid, normal-temperature acid (HSNTA) pretreatment was developed to enhance digestibility while minimizing inhibitor generation. Corn stover was pretreated at 50 °C for 14 days with a solid-liquid ratio of 1:0.3 (56.5 % w/w solid loading), resulting in a total sugar recovery of 90.9 %. Enzymatic hydrolysis yielded 89.5 % glucan and 81.2 % xylan conversion. Kinetic analysis revealed that, under high-solid conditions, cellulose was primarily hydrolyzed into gluco-oligomers due to limited acid diffusion constraints. Xylan exhibited biphasic degradation comprising fast- and slow-reacting fractions, while lignin degradation was selective, occurring mainly in accessible regions. Kinetic models were established to quantitatively interpret the degradation behavior of individual components. These findings highlight the unique challenges and dynamics of biomass degradation under high-solid, normal-temperature conditions, addressing the importance of optimizing pretreatment parameters to maximize sugar yield.

Review on the preparation of fuels and chemicals based on lignin

Lignin is by far the most abundant natural renewable aromatic polymer in nature, and its reserves are second only to cellulose. In addition to the rich carbon content, the structure of lignin contains functional groups such as benzene rings, methoxyl groups, and phenolic hydroxyl groups. Lignin degradation has become one of the high value, high quality and high efficiency methods to convert lignin, which is of great significance to alleviating the current energy shortage and environmental crisis. This article introduces the hydrolysis methods of lignin in acidic, alkaline, ionic liquids and supercritical fluids, reviews the heating rate, the source of lignin species and the effects of heating rate on the pyrolysis of lignin, and briefly describes the metal catalysis, oxidation methods such as electrochemical degradation and photocatalytic oxidation, and degradation reduction methods using hydrogen and hydrogen supply reagents. The lignin degradation methods for the preparation of fuels and chemicals are systematically summarized. The advantages and disadvantages of different methods, the selectivity under different conditions and the degradation efficiency of different catalytic combination systems are compared. In this paper, a new approach to improve the degradation efficiency is envisioned in order to contribute to the efficient utilization and high value conversion of lignin.