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Ostwald Process

4NH₃ + 5O₂ → 4NO + 6H₂O
Quick Reference
Formula / Notation4NH₃ + 5O₂ → 4NO + 6H₂O
Also Known AsNitric acid synthesis, catalytic ammonia oxidation, nitric acid process

What is Ostwald Process?

The Ostwald Process is the industrial method for producing nitric acid (HNO₃) from ammonia (NH₃). Developed by Wilhelm Ostwald in 1902, it involves three main steps: (1) catalytic oxidation of ammonia to nitric oxide (NO) using a platinum-rhodium catalyst at 850°C; (2) oxidation of NO to nitrogen dioxide (NO₂); (3) absorption of NO₂ in water to form nitric acid. It is one of the most important industrial chemical processes.

Formula & Notation

4NH₃ + 5O₂ → 4NO + 6H₂O

Other Names / Synonyms: Nitric acid synthesis, catalytic ammonia oxidation, nitric acid process

Properties & Characteristics

Step 1: 4NH₃ + 5O₂ → 4NO + 6H₂O (Pt-Rh catalyst, 850°C, 1-10 atm). Step 2: 2NO + O₂ → 2NO₂. Step 3: 3NO₂ + H₂O → 2HNO₃ + NO (NO recycled). Overall: NH₃ + 2O₂ → HNO₃ + H₂O. Products: 50–68% HNO₃ solution. Annual production: ~50 million tonnes HNO₃.

Uses & Applications

Production of fertilizers (ammonium nitrate, NH₄NO₃). Explosives manufacturing (TNT, nitroglycerin). Nylon production (adipic acid synthesis). Metal etching and pickling. Rocket propellants. Pharmaceutical synthesis.

Safety Information

All stages involve hazardous substances: NH₃ (toxic, flammable), NO (toxic), NO₂ (highly toxic, corrosive), HNO₃ (strong oxidizing acid, corrosive). Platinum catalyst poisoned by sulfur. High-pressure operations require engineering controls. Industrial exposure limits: NO₂ = 3 ppm (TLV-C).

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Ostwald Process
Formula 4NH₃ + 5O₂ → 4NO + 6H₂O
Synonyms Nitric acid synthesis, catalytic ammonia oxidation, nitric acid process

Frequently Asked Questions

The Ostwald Process is the industrial method for producing nitric acid (HNO₃) from ammonia (NH₃). Developed by Wilhelm Ostwald in 1902, it involves three main steps: (1) catalytic oxidation of ammonia to nitric oxide (NO) using a platinum-rhodium catalyst at 850°C; (2) oxidation of NO to nitrogen dioxide (NO₂); (3) absorption of NO₂ in water to form nitric acid. It is one of the most important industrial chemical processes.

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