Given ammonia’s strong reducing property, why doesn’t it react with oxygen at higher temperatures?
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Catalysts are generally required.
NH3 and O2 (or air) react to produce NO at temperatures of 450–500°C in the presence of a catalyst; the equation is: 4NH3 + 5O2 → 4NO + 6H2O. A catalyst is required for this reaction
This is a problem related to reaction engineering, and those who work on process development are likely not good at explaining it. The ignition point of ammonia is 651°C, and this synthesis temperature should not reach that level; although the ignition temperature decreases under pressure, the exact values are unknown. That’s why a catalyst is needed. It has not been determined whether this reaction is exothermic or endothermic; it is also unclear whether the rise in temperature will accelerate the reaction after it begins, or whether an endothermic reaction requires heating to be sustained
Ammonia does not have strong reducing properties, as nitrogen itself has a relatively high electronegativity. Ammonia oxidation is exothermic. There are very few incidents of ammonia catching fire or exploding; although there have been reports of explosions in tanks containing ammonia, these reports are vague and the exact causes remain unclear
“Ammonia can indeed explode in the air! The explosive limit of its vapor mixture with air is 16–25%”
There have been reports of ammonia tank explosions, but unfortunately none contain detailed analytical discussions
Was it the leak and fire of liquid ammonia used for freezing at that chicken processing plant in the north where over a hundred people died?
Ammonia has strong reducing properties; how was this conclusion reached? All of ammonia’s single chemical bonds are of the hybridized s bond type, which makes it relatively stable.