Aluminium phosphate

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Aluminium phosphate
Aluminium phosphate
Other names
Aluminum phosphate
Aluminium monophosphate
Phosphoric acid, aluminium salt (1:1)
3D model (JSmol)
ECHA InfoCard 100.029.142
RTECS number TB6450000
Molar mass 121.9529 g/mol
Appearance White, crystalline powder
Density 2.566 g/cm3, solid
Melting point 1,800 °C (3,270 °F; 2,070 K)
Boiling point Decomposes
Solubility Very slightly soluble in HCl and HNO3
1.546 [1]
A02AB03 (WHO)
R-phrases (outdated) R36/37/38
S-phrases (outdated) S26
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Lethal dose or concentration (LD, LC):
4640 mg/kg (rat, oral)
> 4640 mg/kg (rabbit, dermal)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Aluminium phosphate (AlPO4) is a chemical compound. The anhydrous form is found in nature as the mineral berlinite. Many synthetic forms[2] of anhydrous aluminium phosphate are known. They have framework structures similar to zeolites and some are used as catalysts or molecular sieves. The dihydrate, AlPO4·2H2O is found as the minerals variscite and meta-variscite.[3][4] A synthetic hydrated form, AlPO4·1.5H2O is also known.[5] Commercially, an aluminium phosphate gel is available.

Aluminium phosphate (berlinite)[edit]

AlPO4 is isoelectronic with Si2O4, silicon dioxide. Berlinite looks like quartz and has a structure that is similar to quartz with silicon replaced by Al and P. The AlO4 and PO4 tetrahedra alternate. Like quartz, AlPO4 exhibits chirality[6] and piezoelectric properties.[7] Crystalline AlPO4 (berlinite) when heated, converts to tridymite and cristobalite forms, and this mirrors the behaviour of silicon dioxide.[8]

Aluminophosphate molecular sieves[edit]

There are many of aluminium phosphate molecular sieves, generically known as "ALPOs". The first ones were reported in 1982.[9] They all share the same chemical composition of AlPO4 and have framework structures with microporous cavities. The frameworks are made up of alternating AlO4 and PO4 tetrahedra. The denser cavity-less crystalline AlPO4 mineral, berlinite, shares the same alternating AlO4 and PO4 tetrahedra.[8] The aluminophosphate framework structures vary one from another in the orientation of the AlO4 tetrahedra and PO4 tetrahedra to form different-sized cavities, and in this respect they are similar to the aluminosilicate zeolites, which differ in having electrically charged frameworks. A typical preparation of an aluminophosphate involves the hydrothermal reaction of phosphoric acid and aluminium in the form of hydroxide, an aluminium salt such as aluminium nitrate salt or alkoxide under controlled pH in the presence of organic amines.[10] These organic molecules act as templates (now termed structure directing agents, SDAs[2]) to direct the growth of the porous framework.[11]

Related compounds[edit]

Aluminium phosphate dihydrate (variscite and meta-variscite) has a structure that can be regarded as an assembly of phosphate anions, aluminium cations and water. The aluminium cations are six-coordinate.[4]

In medicine an aluminium phosphate sol or gel is used as adsorbent for toxoid and in the dried form, which contains hydrated AlPO4, as an antacid.[12] Industrially the Al-PO4-H2O system is used as the basis of many adhesives, binders and cements.[8]

Aluminium dihydrogenphosphate (Al(H2PO4)3) is a related material formed from combining phosphate and aluminium salts at low pH.


  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ a b Chemistry of Zeolites and Related Porous Materials: Synthesis and Structure Ruren Xu, Wenqin Pang, Jihong Yu, Qisheng Huo, Jiesheng Chen, John Wiley & Sons, 2007, ISBN 978-0-470-82233-3
  3. ^ Roncal-Herrero, T., Rodriguez-Blanco, J.D., Benning, L.G., Oelkers, E.H. (2009) Precipitation of Iron and Aluminum Phosphates Directly from Aqueous Solution as a Function of Temperature from 50 to 200°C. Crystal Growth & Design, 9, 5197-5205. doi: 10.1021/cg900654m.
  4. ^ a b Corbridge DEC 2013, Phosphorus: Chemistry, Biochemistry and Technology, 6th ed., CRC Press, Boca Raton, Florida, ISBN 978-1-4398-4088-7
  5. ^ Lagno, Felipe; Demopoulos, George P. (2005). "Synthesis of Hydrated Aluminium Phosphate, AlPO4·1.5H2O (AlPO4−H3), by Controlled Reactive Crystallization in Sulfate Media". Industrial & Engineering Chemistry Research. 44 (21): 8033–8038. doi:10.1021/ie0505559. ISSN 0888-5885.
  6. ^ Tanaka, Yoshikazu; Kojima, Taro; Takata, Yasutaka; Chainani, Ashish; Lovesey, Stephen W.; Knight, Kevin S.; Takeuchi, Tomoyuki; Oura, Masaki; Senba, Yasunori; Ohashi, Haruhiko; Shin, Shik (2010). "Determination of structural chirality of berlinite and quartz using resonant x-ray diffraction with circularly polarized x-rays". Physical Review B. 81 (14). doi:10.1103/PhysRevB.81.144104. ISSN 1098-0121.
  7. ^ Crystal growth of an α-quartz like piezoelectric material, berlinite, Motchany A. I., Chvanski P. P., Annales de Chimie Science des Materiaux properties, 2001, 26, 199
  8. ^ a b c Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
  9. ^ Wilson, Stephen T.; Lok, Brent M.; Messina, Celeste A.; Cannan, Thomas R.; Flanigen, Edith M. (1982). "Aluminophosphate molecular sieves: a new class of microporous crystalline inorganic solids". Journal of the American Chemical Society. 104 (4): 1146–1147. doi:10.1021/ja00368a062. ISSN 0002-7863.
  10. ^ Zeolites in Industrial Separation and Catalysis Santi Kulprathipanja, John Wiley & Sons, 26 Jan 2010
  11. ^ Zeolites and Catalysis, Jiri Cejka, Avelino Corma, Stacey Zones, John Wiley & Sons, 27 May 2010,ISBN 978-3-527-32514-6
  12. ^ Contemporary Drug Synthesis, Jie Jack Li, Douglas S. Johnson, Drago R. Sliskovic, Bruce D. Roth., John Wiley and Sons, 2004, ISBN 0471-21-480-9

External links[edit]