Biochar characteristics produced via hydrothermal carbonization and torrefaction of peat and sawdust

Biochars made by hydrothermal carbonization and torrefaction of sawdust and peat in a wide temperature range have been studied. A comparative evaluation of the properties of the resulting materials was carried out by the following methods: elemental analysis, FTIR, Raman Spectroscopy, TG/TGA, SEM, Fluorescence analysis, BET. It has been established that hydrothermal carbonization has a greater effect on the degree of carbonification of the initial biomass than torrefaction. Biochars made from peat by this method have a more stable structure and contain asphaltene-like fragments and a developed system of poly-couplings. The combination of these properties makes it possible to use these materials not only as solid commercial carbon dioxide neutral fuel, but also as a promising analogue of fossil coals for the refining process. •Peat hydrochar obtained at 230 °C obsessed asphaltene-like structures.•HTC enables directed evolution of biomass.•Thermal effect on peat is stronger than on sawdust.•HTC reduces more ash in peat then in sawdust.•Polyconjugation systems were found in hydrochars.