Haber-Bosch Process
The Haber-Bosch process is the primary industrial method for synthesising ammonia (NH₃) from atmospheric nitrogen (N₂) and hydrogen (H₂). It is one of the most important chemical processes in history, enabling large-scale nitrogen fertiliser production.
Reaction
N₂ + 3 H₂ → 2 NH₃ (ΔH = −92 kJ/mol)
The reaction is exothermic and reversible. Typical industrial conditions:
| Parameter | Value |
|---|---|
| Temperature | 400–500 °C |
| Pressure | 150–300 atm |
| Catalyst | Iron with K₂O and Al₂O₃ promoters |
| Conversion per pass | 10–15% |
| Overall yield | ~97% (with recycle) |
History
- 1909: Fritz Haber demonstrates laboratory-scale synthesis at 175 atm.
- 1913: Carl Bosch scales the process industrially at BASF, Oppau (Germany).
- 1918: Fritz Haber receives the Nobel Prize in Chemistry.
- 1931: Carl Bosch receives the Nobel Prize in Chemistry.
Energy and Carbon Footprint
The process currently accounts for approximately 1–2% of global energy consumption and 1.4% of global CO₂ emissions, primarily because most hydrogen is derived from natural gas via steam methane reforming (SMR).
Green ammonia production, using electrolytic hydrogen from renewable electricity, is under active development to decarbonise the process.
Significance
It is estimated that the Haber-Bosch process directly supports the nutrition of approximately 50% of the global population by enabling the fertiliser production that underpins modern agriculture.