A New Approach to Kinetic Modeling of Biomass Hydrothermal Carbonization

This study proposes to model hydrothermal carbonization describing the reactions stochastically. A procedure is set up for handling batch reaction data and deducing the probability distributions required for analyzing the process statistically. The progressive formation of the hydrochar and the evolution over time of its composition are connected to the dynamics of Markov processes. The transition probability functions, which rule the solid/liquid reactions, are obtained. The matrix algebra required to evaluate the dynamics of the reacting system is developed. The method furnishes valuable information for the optimization of the industrial reactors. The technique is tested with data concerning batch reactions of both lignocellulosic and agro-food residual biomass carried out at 200 °C, up to 120 min, and at fixed 7:1 water to solid ratio. The model testing also used additional data from the literature. In any case, the accordance between stochastic calculations and experimental data is good. The proposed modeling approach could help to steer the selection of the optimal kinetic pattern among those debated in the literature. The method, fruitful of developments and potentially applicable to the other hydrothermal conversion processes, represents an additional tool for modeling the hydrothermal carbonization.