Generation of biofuel from hydrothermal carbonization of cellulose. Kinetics modelling

•HTC process was simulated.•Process simulation was achieved with cellulose.•Finite elements with Comsol multiphysics was applied.•Atomic ratios, solid yield and HHV was studied.•Chemical composition was described by the model.

Kinetics of cellulose hydrothermal carbonization was investigated over different reactions times and temperatures, developing a first order-reaction model, where chemical and heat transfer processes were connected and resolved simultaneously. According to the model, mass species evolutions are described by sigmoid curves and the presence of an induction period confirms the importance of taking into account the heat-up time and not only the T-constant period during the experiments. Moreover, the model indicates that temperature plays a main role on cellulose HTC (hydrothermal carbonization) reaction, affecting both pre-exponential and exponential factors of the kinetic constant. Finally, it is interesting to remark, from a practical viewpoint, that the model was able to describe the changes in H/C, O/C and high heating value taking place during cellulose hydrocarbonization, allowing the chemical composition and energy densification to be forecasted.