Preparation of ammonium intercalated vanadyl phosphate by redox intercalation and ion exchange

摘要

Redox intercalation of NH4+ into vanadyl phosphate dihydrate (VOPO4.2H(2)O) leads to a two-phase (NH4)(x)VOPO4.H2O (x = 0.2 - 0.9) compound with interlayer distances of 6.7 and 6.4 Angstrom. Ammonium ions can be incorporated into the interlayer space of VOPO4 also by anion exchange, starting from alkali-metal redox-intercalated vanadyl phosphate MexVOPO4.yH(2)O (Me = Li, Na, K, Rb). Several phases are formed during the ion exchange, one of them with the interlayer distance corresponding to the original MexVOPO4.yH(2)O phase, the second one corresponding to formed (NH4)(x)VOPO4.H2O. In addition, a third phase is formed by the ion exchange when Li0.98VOPO4.1.98H(2)O or Rb0.60VOPO4.1.3H(2)O are used as starting compounds. An opposite ion exchange of NH4+ for Me+ starting from (NH4)(x)VOPO4.H2O does not proceed. (C) 2003 Elsevier Inc. All rights reserved.