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]