Question
Write the principle of the manufacture of H2SO4.
Answer
The principle of the manufacture of H2SO4 by the Contact Process involves the following steps:
- Preparation of sulfur dioxide (SO2) by burning sulfur or by roasting metal sulfides.
S + O2 = SO2 (4FeS2 + 11O2 = 2Fe2O3 + 8SO2) - Conversion of SO2 to sulfur trioxide (SO3) by catalytic oxidation with oxygen using a vanadium pentoxide catalyst at a temperature of around 450-500°C.
2SO2 + O2 = 2SO3 + Heat - Absorption of SO3 in 98% sulfuric acid to produce oleum (a mixture of H2SO4 and SO3).
H2SO4 + SO3 = H2S2O7 - Dilution of oleum with water to obtain the desired concentration of sulfuric acid (typically 98% or 96%).
H2S2O7 + H2O = 2H2SO4 - Recycling of unreacted SO2 and excess oxygen to the oxidation step.