MANUFACTURE OF SULPHURIC ACID IN INDUSTRY
MANUFACTURE OF SULPHURIC ACID IN INDUSTRY
1. Contact process produces more than 90% of the world’s sulphuric acid.
2. The raw materials used for the manufacture of sulphuric aced are sulphur, air and water.
3. The Contact process consists of three stages.
a) Production of suphur dioxide
b) Conversion of sulphur dioxide to sulphur trioxide.
c) Production fo sulphuric acid
4. Stage I: Production of sulphur dioxide
a) Sulphur is burnt in air to produce sulphur dioxide.
S(s) + O2 (g)→SO (g)
b) Burning of metal sulphides such as zinc sulphide and lead sulphide also produces sulphur
Dioxide.
2ZnS(s) + 30 (g) →2SO (g) + 2ZnO(s)
2PbS(s)+ 3O(g)→2SO (g) + 2PbO(s)
c) The sulphur dioxide is then mixed with excess air, The mixture is dried and purified to remove impurities such as arsenic compounds.
d) Arseic compounds found in sulphur will poison the catalyst in the converter, making the catalyst ineffective.
5. Stage II: Conversion of sulphur dioxide to sulphur trioxide
a) The mixture of sulphur dioxide and excess oxygen is passed through a converter.The sulphur dioxide is oxidized to sulphur trioxide. 2SO (g) + O (g)→ 2SO (g) b) Optimum conditions used are as follows. (i) temperature: 450。C (ii) Pressure: 1 atmosphere (iii) Catalyst: Vanadium (V) oxide, V O c) About 97% conversion occurs under these optimum conditions.
6. Stage III: Production of sulphuric acid
a) The sulphur trioxide is first dissolved in concentrated sulphuric acid to form a product called oleum, H S O b) Sulphur trioxide is not dissolved in water to form sulphuric acid, This is because reaction between sulphur trioxide and water is very vigorous and produces a large amount of heat. The reaction causes the production of a large cloud of sulphuric acid mist, The mist is corrosive, pollutes the air and is difficult to condense. c) The oleum is then diluted with water to produce concentrated sulphuric acid of about 98% H2S2O7 (I) + H2O(I) →2H2SO4(aq)
1. Contact process produces more than 90% of the world’s sulphuric acid.
2. The raw materials used for the manufacture of sulphuric aced are sulphur, air and water.
3. The Contact process consists of three stages.
a) Production of suphur dioxide
b) Conversion of sulphur dioxide to sulphur trioxide.
c) Production fo sulphuric acid
4. Stage I: Production of sulphur dioxide
a) Sulphur is burnt in air to produce sulphur dioxide.
S(s) + O2 (g)→SO (g)
b) Burning of metal sulphides such as zinc sulphide and lead sulphide also produces sulphur
Dioxide.
2ZnS(s) + 30 (g) →2SO (g) + 2ZnO(s)
2PbS(s)+ 3O(g)→2SO (g) + 2PbO(s)
c) The sulphur dioxide is then mixed with excess air, The mixture is dried and purified to remove impurities such as arsenic compounds.
d) Arseic compounds found in sulphur will poison the catalyst in the converter, making the catalyst ineffective.
5. Stage II: Conversion of sulphur dioxide to sulphur trioxide
a) The mixture of sulphur dioxide and excess oxygen is passed through a converter.The sulphur dioxide is oxidized to sulphur trioxide. 2SO (g) + O (g)→ 2SO (g) b) Optimum conditions used are as follows. (i) temperature: 450。C (ii) Pressure: 1 atmosphere (iii) Catalyst: Vanadium (V) oxide, V O c) About 97% conversion occurs under these optimum conditions.
6. Stage III: Production of sulphuric acid
a) The sulphur trioxide is first dissolved in concentrated sulphuric acid to form a product called oleum, H S O b) Sulphur trioxide is not dissolved in water to form sulphuric acid, This is because reaction between sulphur trioxide and water is very vigorous and produces a large amount of heat. The reaction causes the production of a large cloud of sulphuric acid mist, The mist is corrosive, pollutes the air and is difficult to condense. c) The oleum is then diluted with water to produce concentrated sulphuric acid of about 98% H2S2O7 (I) + H2O(I) →2H2SO4(aq)