Nitric Acid Manufacturing by Engineer Ghulam Abbas (Chemical Engineering Lecturer University of Gujrat)

1. Nitric Acid Manufacturing
Class Lecture By
Engr. Ghulam Abbas

2. Nitric Acid
• Transparent
• Yellowish colour(due to NO2 emission)
• Hygroscopic
• Corrosive and attack all metals
• 78 C boiling point and -42C its freezing
point
• 100 % HNO3 only stable at below 0C

3. Manufacturing methods
• From Chile Saltpeter
• NaNO3 and H2SO4 react to produce
NaHSO4 and HNO3
• Electric Oxidation of Air (N2 & O2)
• N2 & O2 react (in the presence of
electricity) to form NO and more O2
produces NO2 and this is then mixed with
H2O to produce HNO3

4. By Catalytic Oxidation of NH3
• HNO3 is produced by High pressure
method (Dupont Plant or American Plant)
Raw Materials
• Liq NH3
• Air
• H2O

5. Conti..
• NH3 is produced by reaction
• N2+3H2 to 2NH3 at 500C and 200 Atm
and Iron oxide act as catalyst.
• N2 is obtained by fixation and H2 through
processing of Natural gas
• Air consists of 79%N and 21% O2
• H2O for absorption of Nitrogen per oxide
and for raising steam

6. Catlayst
• Platinum, Rhodium alloy composed of
90% Pt and 10%Rh
• Rhodium promotes catalytic actvity of Pt
and called as promoter.
• Rh also act as erosion resister
• Catalyst is in the form of 80 mesh gauze

7. Types of Plant
• Two types
• Single pressure Plant (American / Dupont
plants)
• Dual pressure plants also called European
Plants.
• Earlier,oxidation-absorption,reoxidation-
reabsorption process was operated at
Atmopheric pressure but it was expesive
as equipment was large. And HNO3 conc
55-55%

8. Conti..
• Single pressure plants have lower capital
cost and produced more steam
• Dual pressure unit has lower catalyst cost
and a slight higher yield.
• But overall costs are almost competitive

11. HNO3 Concentration
• 61-65% HNO3 by this method
• Distillation can be used for higher conc
upto 68.8% but not more than this as
azeorope is formed
• Distillation in the presence of
H2SO4(dehydrating agent) to give 70-75
% HNO3.