XII Chemistry BIEK Topic - Nitric Acid (Ostwald's Process)

Nitric Acid (Ostwald's Process)
Introduction

On industrial process three methods are employed for the manufacture of nitric acid. Ostwald's Process uses Ammonia as raw material.




Ostwald's Process
When a mixture of ammonia and air is passed through a catalytic chamber containing electrically heated Platinum Gauze, (NO) nitric oxide is formed. This nitric oxide combines with more oxygen to form nitrogen dioxide (NO2). This gas is then absorbed by water to form nitric acid. The plant used in Ostwald's Process consist of following parts.


1. Catalytic Chamber

A mixture of pure and dry ammonia is passed through a catalytic chamber containing heated (800ºC) platinum, which serves as catalyst. Here ammonia is completely oxidized to nitric oxide.


2. Oxidation Tower

The nitric oxide is passed into oxidation tower where the temperature of gases falls to 200ºC - 250ºC. At this temperature nitric is oxidized to nitrogen dioxide.

2NO + O2 ----> 2NO2


3. Absorption Tower

Now the gases containing NO2 and oxygen are than sent to a series of absorption tower, which is filled with broken quartz and water is showered from top of the tower. Then NO2 reacts with H2O in the presence of oxygen to form HNO3.

4NO2 + 2H2O + O2 ----> $HNO3