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Describe the Ostwald’s process.

Describe the Ostwald’s process.

Answers

Kavungya
(a). Introduction
- Nitric acid is manufactured by the catalyst oxidation of ammonia and dissolving the products in water.
(b). Raw materials
- Atmosphere air
- Ammonia from Haber process.
(c). Conditions
- Platinum-rhodium catalyst or platinum gauze.
- The ammonia-air mixture must be cleaned (purified) to remove dust particles which could otherwise poison the catalyst.
(d). Chemical reactions.
Step 1: Compressor reactions.
- Ammonia and excess air (oxygen) (1:10 by volume) is slightly compressed.
- The mixture is then cleaned to remove particles which would otherwise poison the catalyst.
- They are then passed to the heat exchanger.
Step 2: Heat exchanger and catalytic chamber.
- In the heat exchanger, the gaseous mixture is heated to about 900oC and then passed over a platinum-rhodium catalytic chamber.
- An exothermic reaction occurs and ammonia is oxidized to nitrogen (II) oxide and steam.
- The exothermic reaction once started, provides the heat necessary to maintain the required catalytic temperature.
-This is of economical advantage i.e. electrical heating of catalyst is not continued hence lowering production costs.
Step 3: Heat exchanger.
- The hot products from catalytic chamber are again passed back through the heat exchanger.
- The hot gases are cooled and then passed into the cooling chamber.
Step 4: Cooling chamber
- Once cooled, the NO is oxidized to NO2 by reacting it with excess oxygen.
Step 5: Absorption towers:
- The NO2 in excess air is then passed through a series of absorption towers where they meet a stream of hot water and form nitric (V) acid and nitrous (III) acid.
- The so produced nitrous (III) acid is oxidized by oxygen in excess air to nitric (V) acid so that the concentration of nitric acid in the solution (liquid) gradually increases.
Kavungya answered the question on April 30, 2019 at 09:31

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