HNO3 MANUFACTURING WITH PROCESS FLOW DIAGRAM

From Chile saltpeterNaNO3 and H2SO4 react to produce NaHSO4 and HNO3

Electric oxidation of airN2 and O2 react (in the presence of electricity) to form NO and more O2

Produces NO2 and then this is mixed with water to produce HNO3

By catalytic oxidation of ammonia

(Ostwald’s Process)

Fuming Nitric Acid

A red liquid made by bubbling NO2 gas through concentrated HNO3

Concentrated Nitric Acid

It is of the density of 1.5, containing 98% HNO3

Strong Nitric Acid

It is of the density of 1.4, containing 65% HNO3

Ammonia

Water

Air

Catalyst (Platinum-rhodium gauze)

Oxidation of ammonia

Oxidation of nitric oxide

Absorption of NO2

Mixture of air & ammonia heated to 220˚C

passed through a metal gauze made of platinum (90%) & Rhodium (10%).

3X10-4sec

Reaction produces a lot of heat energy.

Energy is used to keep reaction vessel temp at 975-1225 K, typically 1200K

Side reaction: favored by high pressure and over heated catalyst

Colourless nitrogen monoxide gas produced from 1st stage is then reacted with oxygen from the air to form brown nitrogen dioxide gas (NO2).

The nitrogen dioxide is then dissolved in water to produce nitric acid

NO2+H20 HNO3+HNO2

HNO2 + NO2 HNO3 + NO

Thus overall reaction

2NO2+H20 2HNO3+ NO

Prepare a flow chart to show thesequence of processes used to convertammonia to concentrated nitric acid.Write equations for significant chemicalreactions beside the appropriatesection of the flow chart.

During the Ostwald process, nitrogenmonoxide is made from ammonia atabout 900°C and then cooled to 30°Cbefore being reacted with air to makenitrogen dioxide. Both these reactionsare exothermic. Why are thetemperatures used for these reactionsso different?

As the gas passes through the catalyst bed in the converter during nitric acid manufacture, its temperature increases. The gas must be cooled before it is mixed with air.

Why does the temperature of the gas rise?

Why is it necessary to cool the gas?

What side benefit is obtained from the need to cool gases?

Describe two ways that expenses are minimized in the Ostwald process.