Biomass type

Process type


Operating conditions

Main findings


Olive mill





thermal carbonization (HTC)


・ catalyst: citric acid;

・ temperature: 180˚C or 220˚C;

・ residence time: 14 h;

・ pressures: 9 bar (180˚C) and 24 bar (220˚C)

・ the organic carbon content of the biochar is enhanced with increasing HTC temperature and pressure;

・ mass balance considerations confirm that the yield of biochar is associated with a low fraction of carbohydrates in OMW


Two-phase olive mill waste (TPOMW)



・ pressure: 0.1 - 1.5 MPa;

・ peak temperature: 400˚C - 550˚C;

・ heating rate: 5 K∙min−1

・ biochar yield from pyrolysis of TPOMW decreased when both peak temperature and pressure increased;

・ an increase of both peak temperature and pressure results in a higher fixed-carbon yield and devolatilization rate


Sunflower husks

thermochemical liquefaction

574 gchar∙kg−1 husks

・ temperature: 280˚C;

・ feed rate 30 g∙kg−1;

・ solvent: distilled water, methanol, ethanol, isopropanol and n-butanol

・ HHV of the biochars were higher than that of the feedstock;

・ biochars compared favorably with coal on a Van Krevelen diagram;

・ at temperatures below 280˚C, the charring of the biomass is not complete, with some of the cell wall lignin still intact


Vine shoots-derived biochar

laboratory-scale fixed-bed slow pyrolysis


・ heating rate: ~5 K∙min−1;

・ pressure: 0.1 - 1.1 Mpa;

・ temperature: 400˚C - 600˚C

・ particle size the most significant factor in determining the potential stability of biochars;

・ operating at higher peak temperatures leads to the production of more stable materials;

・ the absolute pressure decreased the tar content in the producer gas;

・ no statistically significant effects of increasing pressure on the aromaticity of biochar