Thermodynamics and kinetics of Doum (Hyphaene thebaica) shell using thermogravimetric analysis: A study on pyrolysis pathway to produce bioenergy

• Published in: Renewable energy 2022-11, Vol.200, p.1275-1285
• Main Authors: Mohammed, Habu Iyodo, Garba, Kabir, Ahmed, Saeed I., Abubakar, Lawan G.
• Format: Article
• Language: English
• Subjects: bioenergy; biomass; carbon; Doum (Hyphaene thebaica) shell; endothermy; hydrogen; Hyphaene thebaica; Kinetics; pulp; Pyrolysis; Thermodynamics; Thermogravimetric analysis; thermogravimetry; viability
• ISSN: 0960-1481; 1879-0682
• DOI: 10.1016/j.renene.2022.10.042

Doum (Hyphaene thebaica) palm pulp used to produce local beverages left behind enormous, difficult to manage Hyphaene thebaica Shell (HTS) wastes. To pioneer the determination of HTS bioenergy potential, compositional and thermogravimetric analyses to determine the kinetic and thermodynamic characteristics were employed. The HTS had 5.50 wt% hydrogen, 42.50 wt% carbon, and 74.31 wt% volatile matter. The FTIR functional groups matched those found in other recognised biomass sources. Thermogravimetry revealed that HTS pyrolysis occurred in three stages. In total, nearly 70% of the biomass was lost between 32 and 900 °C, with 50% of the loss in the active pyrolysis zone. The average activation energies for the Iso-conversional methods' Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Starink models respectively, were 118.15, 142.81 and 139.56 kJ/mol. The Flynn-Wall-Ozawa technique best fit the pyrolysis data according to the Akaike information criterion (AIC). The multi-step pyrolysis reactions were controlled by the diffusion and contraction mechanisms of Coats-Redfern method, with activation energies of 38.83 and 16.62 kJ/mol, respectively. According to the AIC, the pyrolysis can be accurately predicted by the Gistling-Brounshtein kinetic model. The pyrolysis reactions have a high-degree of disorder, are endothermic, irreversible, and non-spontaneous. The outcome of the study ascertained the HTS viability for bioenergy production. •Thermo-kinetic studies for the pyrolysis of Hyphaene thebaica shell was studied through thermogravimetry.•The pyrolysis occurred with 50% weight loss in the active pyrolysis zone.•Activation energies from the Iso-conversional methods ranges from 118.15 to 42.81 kJ/mol.•Akaike information criterion revealed Gistling-Brounshtein and Flynn-Wall-Ozawa models can predict the pyrolysis.•The pyrolysis devolatilisation was accomplished via complex multi-step reactions.