• Post-treatment increased aromatization degree of hydrothermally derived carbon.
  • Combustion behavior of HTC coal can be adjusted by thermal post-treatment.
  • Calculated kinetic parameters of samples agreed well with the reaction mechanism.


Hydrothermal and pyrolytic carbonization were used in this study to prepare a range of carbonaceous materials from corn starch powder. The objective of the study was to investigate the relationship between microstructures of the hydrothermally carbonized materials synthesized by a two-step carbonization process and their thermophysical and thermochemical properties. Differences in thermal behavior, as observed by thermogravimetric measurements conducted in air, were investigated by supplementary studies using elemental and proximate analysis, Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS) characterisation and weight loss kinetic modeling. The results indicated that the degree of the aromatization of obtained materials with higher carbon contents could be increased by subsequent annealing at higher temperatures. The resulting materials with different carbon skeletons displayed different kinetic behavior upon heating. Kinetic modeling of the thermogravimetric data revealed a low temperature and a high temperature combustion region with different kinetics parameters, thus demonstrating the potential of hydrothermal carbonization (HTC) as a synthesis strategy for fine-tuned functional high-purity combustion fuel preparation.

Graphical abstract