Modelling the production of solid and liquid products from the hydrothermal carbonisation of two biomasses

This work focuses on the hydrothermal carbonisation (HTC) of two bioresources, olive stones (OS) and beechwood (BW), within the ranges of temperature and time of 160-240 °C and 1-24 hours, respectively. The final pH of the liquid phase, the yields of solid and liquid, and the nature and amounts of a broad range of molecules (two furanic and nine phenolic compounds) were produced and studied. The experimental results obtained were discussed in relation to predictive equations developed in a previous study (Borrero-López et al., 2018) regarding the cellulose, hemicellulose and lignin contents of the two bioresources. Adequate fits were obtained for the pH of the liquid phase (9-11% overestimation for OS and BW, respectively), the yields of solid (7-8% error for OS and BW, respectively) and liquid (6-16% error for OS and BW, respectively) and the production of 5-hydroxymethylfurfural and several phenolic compounds, while some discrepancies for the production of furfural and a few phenolic compounds were observed but were properly analysed and discussed.