give your observation when temperature exceeds 50 degrees in the oxidation tower in Ostwald process
Answers
Explanation:
Ostwald Process for making Nitric Acid
Step 1 – Catalytic Oxidation Reaction
Primary Oxidation (Formation of Nitric Acid)
The main goal in this process is the conversion of ammonia into nitric acid. The process begins in a catalyst chamber where one ammonia part and eight oxygen parts are introduced by volume. The chamber temperature is around 600oC. This chamber uses a catalyst-like platinum gauze or copper and nickel can also be used.
The oxidation of ammonia takes place and it is converted into nitric oxide (NO). The process is reversible and exothermic. The change in temperature encourages a forward reaction.
4NH3 + 5O2 ↔ 4NO + 6H2O | H -24.8 Kcal/mol
Secondary Oxidation (Formation Of Nitrogen Dioxide)
The nitric oxide gas produced by oxidation of ammonia is in a very hot state. It is passed through a heat exchanger in which the temperature of nitric oxide is lowered to 150oC. After cooling, nitric oxide is transferred to another oxidizing tower where nitrogen dioxide (NO2) is oxidized at about 50oC.
2NO + O2 ↔2 NO2
Step 2 – Absorption of No2 (Formation of HNO3)
In a special absorption tower containing water, the nitrogen dioxide from the secondary oxidation chamber is introduced. NO2 gas is passed through a tower where it absorbs the water. Nitric acid is then obtained through this process.
3NO2 + H2O -> 2HNO3 + NO
Nitric acid that is obtained is very dilute. NO is recycled to increase the concentration level which is generally kept around 68 per cent. The acid-in-water solution can also be dehydrated by distillation with sulfuric acid. Here, the pressure is kept between 4–10 standard atmospheres and the temperature is set at 870–1,073 K.
This reaction is exothermic as there is a release of energy. However, since the water and oxygen are constantly added to this cycle as reactants, the increasing concentration will create optimal equilibrium conditions.
Sometimes when producing nitric acid by the Ostwald process can be dangerous due to unfavourable conditions that may arise. More significantly, the concentration and corrosive behaviour of nitric acid can be a safety hazard.