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Updated: Jul 19, 2025
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Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments
Published on: May 11, 2017
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Anhydrous Aluminum Carbonates and Isostructural Compounds
Lkhamsuren Bayarjargal1, Dominik Spahr1, Victor Milman2
1Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt 60438, Germany.
Inorganic Chemistry
|August 14, 2023
Summary
Researchers synthesized novel aluminum carbonates, Al2[C2O5][CO3]2 and Al2[CO3]3, under high pressure and temperature. These compounds, featuring unique carbonate structures, can be recovered at ambient conditions and offer insights into deep Earth carbon storage.
Area of Science:
- High-pressure mineral physics and inorganic chemistry.
- Investigating the behavior of oxides and carbonates under extreme conditions.
Background:
- Understanding the Earth's deep carbon cycle requires knowledge of carbon's behavior under high pressures and temperatures.
- Aluminum oxides (Al2O3) are relevant to mantle compositions, but their high-pressure carbonate phases are not well-characterized.
Purpose of the Study:
- To synthesize and characterize new anhydrous aluminum carbonate phases.
- To determine the structural properties and formation conditions of these carbonates.
- To explore the potential for similar structures in other metal oxides and their implications for deep Earth carbon storage.
Main Methods:
- High-pressure and high-temperature synthesis of aluminum carbonates from Al2O3 and CO2.
- Characterization using Raman spectroscopy and X-ray diffraction for structural analysis.
- Density functional theory (DFT) calculations to predict reactions with other metal oxides.
Main Results:
- Successfully synthesized two anhydrous aluminum carbonates: Al2[CO3]3 and Al2[C2O5][CO3]2.
- Al2[CO3]3 forms at 24-28 GPa, characterized by isolated carbonate groups.
- Al2[C2O5][CO3]2 forms above 38 GPa, featuring pyrocarbonate and trigonal carbonate groups, and octahedrally coordinated cations.
- Both synthesized aluminum carbonates are recoverable under ambient conditions.
- DFT predicts isostructural compounds for Fe2O3, Ti2O3, Ga2O3, In2O3, and MgSiO3.
- MgSi[C2O5][CO3]2 is predicted stable in the mantle and offers novel carbon speciation for storage.
Conclusions:
- New aluminum carbonate structures, Al2[CO3]3 and Al2[C2O5][CO3]2, have been synthesized and structurally elucidated.
- The pyrocarbonate-bearing Al2[C2O5][CO3]2 structure type is predicted to form in other metal oxides under high pressure.
- This structure type provides a potential mechanism for significant carbon storage in the deep Earth, incorporating abundant mantle elements.
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