Study objective | Operating condition | Feedstock type | Observation | Reference |
To determine the influence of production conditions on the yield and environmental stability of biochar | pyrolysis temperatures: 350˚C - 550˚C; heating rate: 8˚C min−1; holding time: 60 min | pine, mixed larch and spruce chips, softwood pellets | ・ biochar stability increases with increasing pyrolysis temperature; ・ the yield of biochar decreases with the peak pyrolysis temperature | [53] |
To investigate the effect of pyrolysis temperature and heating rate on biochar from pyrolysis of safflower seed press cake | temperatures:400˚C, 450˚C, 500˚C, 550˚C and 600˚C heating rates: 10˚C, 30˚C and 50˚C min−1 20 g of biomass samples (SPC) | safflower seed press cake | ・ at 600˚C biochar has highest fixed carbon content, FC (80.7%), carbon (73.8%), higher heating value, HHV (30.3 MJ∙kg−1) and lowest volatile matter content, VM (9.80%); ・ biochars had low BET surface areas (1.89 - 4.23 m2/g) containing predominantly aromatic compounds; ・ biochar yield decreased linearly with increasing temperature; ・ increase in heating rate reduced VM, FC and BET surface area but had no clear effect on HHV, elemental composition and pH | [55] |
To determine the physical and thermochemical characterization of rice husk char as a potential biomass energy source | temperature: 200˚C - 650˚C heating rate: 50˚C holding time: 60 min | rice husk | ・ 400˚C the optimum temperature with char having moderate HHV; ・ order of reaction in combustion zone was ~1, the activation energy 73.4 kJ/mol with pre-exponential factor 4.97 × 104 min−1 | [56] |
Characterization of char from rapid pyrolysis of rice husk | ・ temperature: 1200˚C ・ rice husk particles injected into the centre of the reactor at extremely high heating rates (≈1 × 104˚C/s), short residence times under a N2 environment at atmospheric pressure |
rice husk | ・ based on SEM, pore surface of char particle became increasingly rough in the middle of pyrolysis; ・ the surface area of char increased with pyrolysis process to a maximum value of 56.95 m2/g at pyrolysis reaction ratio (Rp = 0.90); ・ the H/C, O/C and N/C ratios of the char changed with different trends when the pyrolysis reaction ratio increased; ・ FTIR studies indicated a gradual decrease in the intensities of OH, C-H and C-O stretches with pyrolysis process | [57] |
Characterization of biochars to evaluate recalcitrance and agronomic performance | ・ pyrolyzing the feedstocks in 50˚C increments from 300˚C to 600˚C ・ holding at the target temperature: 15 - 20 min ・ about 3 kg of feedstock manually placed into main chamber purged with N2 while running the mixer | Bull manure, corn, dairy manure, hazelnut, oak, pine and poultry manure | ・ biochar ash contents varied from 0.4% to 88.2%, VM from 13.2% to 70.0%, and fixed carbon from 0% to 77.4% (w/w); ・ pyrolysis temperature and FC increase proportionally for low-ash biochars, but decrease for biochars with >20% ash; ・ nitrogen recovery varied depending on feedstock used at a pyrolysis temperature of 600˚C; ・ at 600˚C, fixed carbon production ranged from no enrichment in poultry biochar to a 10-fold increase in corn biochar; ・ woody feedstock demonstrated the greatest versatility with pH values ranging from 4 to 9 | [37] |