TY - JOUR
T1 - Kinetics of antigorite dehydroxylation for CO2 sequestration
AU - Zahid, Sana
AU - Oskierski, Hans C.
AU - Oluwoye, Ibukun
AU - Brand, Helen E.A.
AU - Xia, Fang
AU - Senanayake, Gamini
AU - Altarawneh, Mohammednoor
AU - Dlugogorski, Bogdan Z.
N1 - Funding Information:
Part of this work was carried out on the powder diffraction beamline at the Australian Synchrotron, ANSTO, under Proposal 13048. S.Z. thanks Murdoch University for a Murdoch International Postgraduate Scholarship (MIPS) and acknowledges the Australian Institute of Nuclear Science (AINSE) Limited for providing a Postgraduate Research Award (PGRA). H.C.O. thanks the School of Engineering and IT and the College of Science, Health, Engineering and Education, Murdoch University, for financial support via the NSSG and Small Grant schemes, respectively.
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/6/30
Y1 - 2022/6/30
N2 - Heat-treatment of serpentine minerals generates structural amorphicity and increases reactivity during subsequent mineral carbonation, a strategy for large-scale sequestration of CO2. This study employs thermal analyses (TGA-DSC) in conjunction with in-situ synchrotron powder X-ray diffraction (PXRD) to record concurrent mass loss, heat flow, and mineralogical changes during thermal treatment of antigorite. Isoconversional kinetic modelling demonstrates that thermal decomposition of antigorite is a complex multi-step reaction, with activation energies (Eα) varying between 290 and 515 kJ mol−1. We identify three intermediate phases forming during antigorite dehydroxylation, a semi-crystalline chlorite-like phase (γ-metaserpentine) showing an additional reaction pathway for the decomposition of Al2O3-rich antigorite into pyrope, and two distinct amorphous components (α and β-metaserpentine) which convert into forsterite and enstatite at higher temperature, respectively. The combination of isoconversional kinetics with in-situ synchrotron PXRD illustrates, for the first time, that local crystal structure changes, related to intermediate phase and forsterite formation, are responsible for the steep increase in activation energy above 650 °C and only 49% dehydroxylation can be achieved prior to this increase. This suggests that the high thermal stability of Al2O3-rich antigorite would severely limit Mg extraction during application of mineral carbonation under flue gas conditions.
AB - Heat-treatment of serpentine minerals generates structural amorphicity and increases reactivity during subsequent mineral carbonation, a strategy for large-scale sequestration of CO2. This study employs thermal analyses (TGA-DSC) in conjunction with in-situ synchrotron powder X-ray diffraction (PXRD) to record concurrent mass loss, heat flow, and mineralogical changes during thermal treatment of antigorite. Isoconversional kinetic modelling demonstrates that thermal decomposition of antigorite is a complex multi-step reaction, with activation energies (Eα) varying between 290 and 515 kJ mol−1. We identify three intermediate phases forming during antigorite dehydroxylation, a semi-crystalline chlorite-like phase (γ-metaserpentine) showing an additional reaction pathway for the decomposition of Al2O3-rich antigorite into pyrope, and two distinct amorphous components (α and β-metaserpentine) which convert into forsterite and enstatite at higher temperature, respectively. The combination of isoconversional kinetics with in-situ synchrotron PXRD illustrates, for the first time, that local crystal structure changes, related to intermediate phase and forsterite formation, are responsible for the steep increase in activation energy above 650 °C and only 49% dehydroxylation can be achieved prior to this increase. This suggests that the high thermal stability of Al2O3-rich antigorite would severely limit Mg extraction during application of mineral carbonation under flue gas conditions.
KW - Antigorite
KW - Isoconversional kinetics
KW - Mineral carbonation
KW - Synchrotron powder X-ray diffraction
KW - Thermal dehydroxylation
KW - Thermogravimetric analysis
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U2 - 10.1016/j.mineng.2022.107630
DO - 10.1016/j.mineng.2022.107630
M3 - Article
AN - SCOPUS:85131947411
SN - 0892-6875
VL - 184
JO - Minerals Engineering
JF - Minerals Engineering
M1 - 107630
ER -