Chemical Process Industries

1. SULPHURIC ACID
Prepared by- Mr. Vishal B. Thakare
(M.Tech, Chemical SVNIT Surat)
Assistant Professor PARUL UNIVERSITY
Vadodara
vishalbt88@gmail.com

2. SULFURIC ACID
 Sulfuric acid (H2SO4) is a highly corrosive strong mineral acid.
 It is a colorless to slightly yellow viscous liquid which is soluble in water
at all concentrations.
 It is one of the most important heavy industrial chemicals due to it has a
number of large-scale uses particularly in the phosphate fertilizer
industry. About 60 % of the sulfuric acid produced is utilized in fertilizer
manufacture.
MANUFACTURE
The Industrial manufacture of sulfuric acid is done mainly by two processes
1. The Lead Chamber process
2. The Contact process
3. DCDA process

3. THE CONTACT PROCESS
Raw Materials
Basis: 1000kg sulfuric acid (100%)
Sulfur dioxide or pyrite (FeS2) = 670kg
Air = 1450-2200Nm3
Reactions
S + O2 SO2 ΔH = - 71.2kcals
2SO2 + O2 2SO3 ΔH = - 46.3kcals
SO3 + H2O H2SO4 ΔH = - 31.1kcals
SO3 +H2SO4 H2S2O7 (Oleum)
H2S2O7 +H2O 2H2SO4

5. The steps in this process are as follow.
1. Burning of sulfur
2. Catalytic oxidation of SO2 to SO3
3. Hydration of SO3
1. Burning of sulfur
Burning of sulfur in presence of dry air is carried out in sulfur pyrite
burner. As SO2is needed for the catalytic oxidation and prevention of
corrosion, dry air is used in the combustion process. If sulfur contains
carbonaceous impurities, the molten material has to be filtered to
avoid poisoning the catalyst.

6. Catalytic oxidation of SO2 to SO3
The catalyst used is vanadium pentoxide (V2O5) and the pressure and
temperature maintained is 1.2-1.5 and 500-600oC respectively
atmospheres. At this stage 30% catalyst converts about 80% of SO2.
The converter product is cooled by heat exchange at 300C stage where
total yield is fed to a second stage.
Where total yield is increased to 97% by operating at 400-450oC for
favorable equilibrium.
High yield product gases are cooled to 150oC by water and air heat
exchangers and absorbed in oleum fed.