Kinetics of antigorite dehydroxylation for CO2 sequestration

Sana Zahid, Hans C. Oskierski, Ibukun Oluwoye, Helen E.A. Brand, Fang Xia, Gamini Senanayake, Mohammednoor Altarawneh, Bogdan Z. Dlugogorski

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

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.

Original languageEnglish
Article number107630
JournalMinerals Engineering
Volume184
DOIs
Publication statusPublished - Jun 30 2022
Externally publishedYes

Keywords

  • Antigorite
  • Isoconversional kinetics
  • Mineral carbonation
  • Synchrotron powder X-ray diffraction
  • Thermal dehydroxylation
  • Thermogravimetric analysis

ASJC Scopus subject areas

  • Control and Systems Engineering
  • General Chemistry
  • Geotechnical Engineering and Engineering Geology
  • Mechanical Engineering

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