Preparation of Aluminium Phosphates by the Reaction of Diphosphorus Pentaoxide (O'-form) and α-Alumina

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Other Title
  • O'型五酸化二リンとα-アルミナとの反応によるリン酸アルミニウムの合成
  • Preparation of aluminium phosphates by the reaction of diphosphorus pentaoxide (O'-form) and .ALPHA.-alumina.

Abstract

In the reaction of diphosphorus pentaoxide (O'-form) with α-alumina (α-Al2O3), theconditions for formation of various aluminium phosphates (molar ratio of P2O5/Al2O3, heatingtemperature and time, water content of P2O5) were investigated by means of X-ray diffraction, DTA and TG.<BR>( 1 ) The aluminium phosphates produced were orthophosphate AlPO4 (berlinite, cristobaliteform), Al(H2PO4)3 (C-form), triphosphate AlH2P3O10(I-form), metaphosphate Al(P03)3(A, B, E -form), and three unknown compounds. ( 2 ) AlPO4 was easily formed at the molar ratio of P2O5/Al2O3(R) =1 and above 300°C; berlinite was obtained at the water content above 10%, while cristobalite-form was obtaind regardless of the water content of P2O5. Al. (H2PO4)3 was formed at R=1, 200°C when the water content was more than 30%. AlH2P3O10(I-form) was produced at R≥3, 300°C, and at 12-30% of the water content. Al(PO3)3 was formed at high temperatures (above 400°C); the B and E-forms were chiefly obtained at the low water content of P2O5(less than 10%), while the A-form was obtained independent_ of the water content of P2O5. ( 3 ) the reaction rate of P2O5 with α-Al2O3 was mainly influenced by the water content of P2O5 and the reaction was accelerated with an increase in the water content of P2O5. ( 4 ) In the reaction of P2O5 with α-Al2O3, polyphosphoric acid is considered to be formed at first by the hydrolysis of P2O5 and reacts with α-Al2O3 to produce various aluminium phosphates.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1986 (5), 665-670, 1986-05-10

    The Chemical Society of Japan

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