Aluminium carbonate

Aluminium carbonate (Al₂(CO₃)₃), is a carbonate of aluminium. It is not well characterized; one authority says that simple carbonates of aluminium are not known.^[2] However related compounds are known, such as the basic sodium aluminium carbonate mineral dawsonite (NaAlCO₃(OH)₂) and hydrated basic aluminium carbonate minerals scarbroite (Al₅(CO₃)(OH)₁₃•5(H₂O)) and hydroscarbroite (Al₁₄(CO₃)₃(OH)₃₆•nH₂O).^[3][4][5]

Aluminium Carbonate

Names
IUPAC name Dialuminium Tricarbonate
Identifiers
CAS Number	14455-29-9 Y
3D model (JSmol)	Interactive image
ChemSpider	10606614 Y
ECHA InfoCard	100.034.930
PubChem CID	10353966
UNII	1GA689N629 Y
CompTox Dashboard (EPA)	DTXSID30891680 DTXSID40201756, DTXSID30891680
InChI InChI=1S/3CH2O3.2Al/c3*2-1(3)4;;/h3*(H2,2,3,4);;/q;;;2*+3/p-6 Key: PPQREHKVAOVYBT-UHFFFAOYSA-H
SMILES C(=O)([O-])[O-].C(=O)([O-])[O-].C(=O)([O-])[O-].[Al+3].[Al+3]
Properties
Chemical formula	Al2(CO3)3
Molar mass	233.99 g/mol
Appearance	white powder, unstable
Density	3.14 g/cm3
Solubility in water	reacts
Structure[1]
Crystal structure	orthorhombic
Space group	Fdd2
Lattice constant	a = 21.989 Å, b = 10.176 Å, c = 4.4230 Å
Lattice volume (V)	989.7
Formula units (Z)	8
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation

For many years there was no evidence for the existence of a simple aluminium carbonate, Al₂(CO₃)₃, as the combination of Al³⁺ and carbonates are sufficiently alkaline to precipitate aluminium hydroxide and produce carbon dioxide:^[6]

${\displaystyle {\ce {2[Al(H2O)6]^{3+}(aq) + 3CO3^{2-}(aq) -> 2Al(OH)3 (s) + 3CO2 (g) + 9H2O (l)}}}$

However, in 2023, Al₂(CO₃)₃ was produced by heating aluminium oxide at 2300 °C under 24 GPa of carbon dioxide. The resulting solid is stable in air and at room temperature.^[7]

Some minerals contain both aluminium and carbonate. Dawsonite has the formula NaAlCO₃(OH)₂. Hydrotalcites, both synthetic and natural, are layered metal hydroxides comprised in part of aluminium and carbonate.^[8]

Surface carbonate species readily form upon exposure of aluminium oxide to CO₂.^[9]