TY - JOUR
T1 - Pyrolysis and combustion kinetics of thermally treated globe artichoke leaves
AU - Amer, Mahmoud
AU - Brachi, Paola
AU - Ruoppolo, Giovanna
AU - El-Sharkawy, Ibrahim
AU - Ahmed, Mahmoud
AU - Ookawara, Shinichi
AU - Elwardany, Ahmed
N1 - Publisher Copyright:
© 2021
PY - 2021/10/15
Y1 - 2021/10/15
N2 - There are no data in the literature on the energy valorization of globe artichoke (GA) leaves. Thus, an extensive lab-scale experimental torrefaction, carbonization, and coking study was performed. Operative temperatures of 200 °C–1000 °C with 30–120 min residence times were considered. Nonisothermal thermogravimetric analysis was performed at 10, 20, and 40 °C/min heating rates. Pyrolysis and combustion kinetics of raw and thermally treated samples using the Ozawa–Flynn–Wall (OFW) isoconversional method were investigated. All samples exhibited three-stage thermal decomposition behavior: first, moisture and light volatiles evolution common under air and nitrogen; second, carbohydrate fraction decomposition under nitrogen and volatiles combustion; third, lignin decomposition under nitrogen and char combustion. Average activation energy ranges are 54–223 kJ/mol and 223–503 kJ/mol for combustion and pyrolysis, respectively. Some irregular trends appeared when carbonization exceeded 500 °C due to the occurrence of secondary reactions between residual char and evolved gas and the decomposition of some ash components at temperatures reaching 1000 °C. Negative temperature kinetic coefficient appeared at 800–1000 °C as the temperature approached ash softening/fusing temperatures. SEM images indicated amorphous nature and increased porosity from 600 °C, which explains the pyrolysis and oxidation behavior observed in biochar samples produced over this range. Samples pyrolyzed for 30 min showed better elemental and energy results compared to longer times.
AB - There are no data in the literature on the energy valorization of globe artichoke (GA) leaves. Thus, an extensive lab-scale experimental torrefaction, carbonization, and coking study was performed. Operative temperatures of 200 °C–1000 °C with 30–120 min residence times were considered. Nonisothermal thermogravimetric analysis was performed at 10, 20, and 40 °C/min heating rates. Pyrolysis and combustion kinetics of raw and thermally treated samples using the Ozawa–Flynn–Wall (OFW) isoconversional method were investigated. All samples exhibited three-stage thermal decomposition behavior: first, moisture and light volatiles evolution common under air and nitrogen; second, carbohydrate fraction decomposition under nitrogen and volatiles combustion; third, lignin decomposition under nitrogen and char combustion. Average activation energy ranges are 54–223 kJ/mol and 223–503 kJ/mol for combustion and pyrolysis, respectively. Some irregular trends appeared when carbonization exceeded 500 °C due to the occurrence of secondary reactions between residual char and evolved gas and the decomposition of some ash components at temperatures reaching 1000 °C. Negative temperature kinetic coefficient appeared at 800–1000 °C as the temperature approached ash softening/fusing temperatures. SEM images indicated amorphous nature and increased porosity from 600 °C, which explains the pyrolysis and oxidation behavior observed in biochar samples produced over this range. Samples pyrolyzed for 30 min showed better elemental and energy results compared to longer times.
KW - Biochar
KW - Carbonization
KW - Combustion kinetics
KW - Globe artichoke
KW - Pyrolysis kinetics
KW - Torrefaction
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U2 - 10.1016/j.enconman.2021.114656
DO - 10.1016/j.enconman.2021.114656
M3 - Article
AN - SCOPUS:85113378038
SN - 0196-8904
VL - 246
JO - Energy Conversion and Management
JF - Energy Conversion and Management
M1 - 114656
ER -