Ammonium Molybdate Tetrahydrate

Ammonium Molybdate tetrahydrate (NH₄)₆Mo₇O₂₄•4H₂O is the most common hydrate of Ammonium Molybdate.  It is also known as Ammonium Paramolybdate or Ammonium Heptamolybdate.  Ammonium Molybdate is also used in catalyst production, as a corrosion-inhibitor in coatings, and as a Molybdenum precursor for synthetic processes.

Since Ammonium Molybdate tetrahydrate is water-soluble and has low toxicity, it makes a suitable fertilizer for Molybdenum deficiency in plants.  Both the ammonium and molybdate ions are essential sources of nutrients, making it an ideal salt for this purpose.  Both ions are used in nitrogen fixation and for nitrogen reduction.

Molybdate ions are a less toxic alternative than hexavalent chromate anions for corrosion inhibition in coating formulations.  However, research in this area is ongoing because the performance does not yet match that of chromate-based coatings.  Current research is investigating incorporating synergistic ions into the coatings to improve performance.

Ammonium Molybdate readily decomposes below 400° Celsius and can be used to prepare a variety of molybdenum-containing precursors, including: oxides, reduced oxides, mixed oxides, metal powder, or carbide.  The ammonium ions decompose at high temperatures in an inert atmosphere to create a self-reducing environment, allowing for the preparation of metal powder in a faster reaction time and minimizing the use of hydrogen gas.  In air, it can be thermally treated to prepare Molybdenum oxides, particularly Molybdenum Trioxide MoO₃, a low-toxicity catalyst.

References

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