Ammonium octamolybdate

Catalog	ACM12411642-2
CAS	12411-64-2
Structure
Synonyms	Molybdate (Mo8O264-), ammonium (1:4); Ammonium molybdate(VI) ((NH4)4Mo8O26) (7CI); Molybdate (Mo8O264-), tetraammonium (9CI); Molybdic acid (H4Mo8O26), tetraammonium salt (8CI); AOM; Ammonium octamolybdenate; Charmax LS-AOM; Climax A 20171; Climax AOM; Climax AOM-A 2017; Climax AOM-A 20171; Climax AOM-WA 011GA; Climax WA 011GA; HC Starck 02F001; HC Starck AOM; Kemgard STA; LS 030; Prime 100; Prime 110; Tetraammonium octamolybdate; Tetraammonium β-octamolybdate; ZT 03AOM
IUPAC Name	tetraazanium; bis[[[(oxido(dioxo)molybdenio)oxy-dioxomolybdenio]oxy-dioxomolybdenio]oxy]-dioxomolybdenum; dioxido(dioxo)molybdenum
Molecular Weight	1255.66
Molecular Formula	4(NH₄⁺) · (Mo ₈O₂₆⁴⁻)
Canonical SMILES	[NH4+].[NH4+].[NH4+].[NH4+].[O-][Mo](=O)(=O)[O-].[O-][Mo](=O)(=O)O[Mo](=O)(=O)O[Mo](=O)(=O)O[Mo](=O)(=O)O[Mo](=O)(=O)O[Mo](=O)(=O)O[Mo](=O)(=O)[O-]
InChI	InChI=1S/8Mo.4H3N.26O/h;;;;;;;;4*1H3;;;;;;;;;;;;;;;;;;;;;;;;;;/q;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;4*-1/p+4
InChI Key	WWQQKYMUBXDRKA-UHFFFAOYSA-R
Boiling Point	N/A
Melting Point	> 360 °C
Purity	99%
Density	3.18 g/cm³
Solubility	Solubility in H₂O, 4 g/l (25 °C)
Appearance	White powder
Application	Ammonium octamolybdate is a molybdenum-based coordination compound used as a modifier for its flame-retardant properties, such as in the patented preparation of flame retardant and wear-resistant foamed asphalt. After modification of ammonium octamolybdate from its cluster geometry to a one-dimensional coordination polymer, ammonium octamolybdate is used as an olefin epoxidation catalyst.
Storage	Room temperature
Specific Gravity	3.18

Case Study

Chemically-Bridged Ammonium Octamolybdate-Silica Hybrid for Advanced Smoke Suppression in PVC Composites

Suo, Ting-Ting, et al. Composites Part A: Applied Science and Manufacturing 190 (2025): 108650.

Challenge: Improving the poor smoke suppression efficiency of common inert filler SiO2 with affordable additives in the fabrication of polyvinyl chloride (PVC)-based wood-plastic composites (WPCs).
Solution: Developed a chemically-bridged ammonium octamolybdate (AOM)-silica hybrid (MSiO2-AOM) using silane coupling agents to enhance reactivity during combustion.
Key Results:
· Transformative Smoke Reduction: 37% decrease in Total Smoke Production (TSP); 42% lower Maximum Smoke Density (Dsmax); Achieved at just 20 phr (5.0 wt%) loading in PVC WPC.
· Enhanced Material Performance: Superior thermal stability vs. physical AOM/SiO2 blends; Reduced water solubility for improved processing.
· Synergistic Efficiency: MSiO2-AOM outperformed conventional mixtures by creating reactive sites on inert silica and optimizing molybdenum's smoke-suppression chemistry.
Conclusion: Chemical bridging of AOM to silica unlocks unprecedented smoke suppression in PVC composites. The MSiO2-AOM hybrid delivers dramatic reductions in smoke toxicity (37% TSP) and density (42% Dsmax) at minimal loadings - transforming inexpensive silica into a high-performance fire safety solution. This approach establishes AOM as a critical enabler for next-generation building materials.

Ammonium Octamolybdate-Enhanced Hybrid Additive for High-Performance PU Composites

Xu, Pingfan, et al. Journal of Colloid and Interface Science 621 (2022): 385-397.

Challenge: The synthesis of polyurethane (PU) composites with excellent fire retardancy, smoke suppression and mechanical reinforcing as well as environmental sustainability.
Solution: Created an organic-inorganic hybrid additive (ACAPP) by chemically integrating ammonium octamolybdate (AOM) with ammonium polyphosphate (APP) and bio-derived chitooligosaccharide (COS) via eco-friendly synthesis.
Key Results in PU with 15 wt% ACAPP:
· Fire Safety Excellence: Achieved UL-94 V-0 rating; 44.8% reduction in total smoke production; 31.1% lower total heat release; LOI increased to 26.1%.
· Mechanical Enhancement: Improved tensile strength; Maintained material flexibility.
· Synergistic Mechanism: AOM contributed to catalytic char formation; Created reinforced carbon barriers via P-N-Mo synergy.
Conclusion: Through the introduction of AOM in the ACAPP hybrid, the flame retardant PU composites with outstanding smoke suppression (44.8%), V-0 rating at 15% loading, and excellent mechanical reinforcement without loss of flexibility were realized.

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