Describe the theory of manufacture of sulphuric acid by contact process, with all the necessary condition (No technical details are required but equations should be given for each stage of process).
Describe the theory of manufacture of sulphuric acid by contact process, with all the necessary condition (No technical details are required but equations should be given for each stage of process).
Sulphuric acid is manufactured by the contact process. The main steps involved in this process are
1. Production of SO2: By roasting iron pyrites or by burning sulphur
4FeS2 + 11O2 → 2Fe2O3 + 8SO2
S + O2 → SO2 Or S8 + 8O2 → 8SO2
2. Catalytic oxidation of SO2: It is done in the presence of air to produce sulphur trioxide (SO3). The catalyst commonly used in this step is platinum or vanadium pentaoxide.
2SO2 + O2 ⇌ 2SO3 + Heat (exothermic)
The necessary conditions (based on Le Chatelier's principle) that favour the maximum yield of SO3 are
(i) High pressure : A high pressure of around 2 atmospheres is used in the manufacture of sulphuric acid.
(ii) Low temperature : The optimum temperature usually used is 450⁰ - 500⁰ C.
(iii) Use of catalyst : Usually, platinum or vanadium pentoxide is used as the catalyst.
(iv) Excess of oxygen : This favours a high yield of sulphur trioxide.
3. Formation of oleum (H2S2O7 ): This is done through the absorption of sulphur trioxide in 98% sulphuric acid.
SO3 + H2SO4 → H2S2O7
4. Dilution of oleum: This is done to obtain sulphuric acid of the desired concentration.
H2S2O7 + H2O → 2H2SO4
Sulphuric acid is manufactured by the contact process. The main steps involved in this process are
1. Production of SO2: By roasting iron pyrites or by burning sulphur
4FeS2 + 11O2 → 2Fe2O3 + 8SO2
S + O2 → SO2 Or S8 + 8O2 → 8SO2
2. Catalytic oxidation of SO2: It is done in the presence of air to produce sulphur trioxide (SO3). The catalyst commonly used in this step is platinum or vanadium pentaoxide.
2SO2 + O2 ⇌ 2SO3 + Heat (exothermic)
The necessary conditions (based on Le Chatelier's principle) that favour the maximum yield of SO3 are
(i) High pressure : A high pressure of around 2 atmospheres is used in the manufacture of sulphuric acid.
(ii) Low temperature : The optimum temperature usually used is 450⁰ - 500⁰ C.
(iii) Use of catalyst : Usually, platinum or vanadium pentoxide is used as the catalyst.
(iv) Excess of oxygen : This favours a high yield of sulphur trioxide.
3. Formation of oleum (H2S2O7 ): This is done through the absorption of sulphur trioxide in 98% sulphuric acid.
SO3 + H2SO4 → H2S2O7
4. Dilution of oleum: This is done to obtain sulphuric acid of the desired concentration.
H2S2O7 + H2O → 2H2SO4
