Hemicellulose hydrolysis with simultaneous delignification: A reaction-diffusion-structure evolution coupled kinetic...

One-pot fractionation of lignocellulose has been widely investigated as an efficient route for the separation and conversion of lignocellulose components. However, the heterogeneous nature of this process, particularly the coupling between intraparticle diffusion and structural evolution, remains to be further elucidated in current kinetic models. In this study, a reaction-diffusion-structure model was developed for corn-stover fractionation in an acetone/n-pentanol/dilute-acid system. Acid diffusion in cylindrical particles was coupled with hemicellulose hydrolysis and lignin solubilization, while porosity and tortuosity changes caused by component separation were incorporated to update the effective diffusivity. The model reproduced solid-phase fractionation and liquid-phase product formation with an overall normalized RMSE of 0.0466 and an R² of 0.983. Compared with simplified models, incorporating lignin solubilization and pore-diameter-dependent tortuosity improved the description of hemicellulose removal, delignification, and XOS formation. Model analysis indicated that lignin solubilization contributed to pore opening and reduced transport-path tortuosity, which facilitated acid diffusion and hemicellulose hydrolysis. Sensitivity analysis further showed that kinetic and transport-related parameters affected different model responses. These results provided an interpretable framework for analyzing reaction-diffusion-structure coupling during lignocellulose fractionation.