Chapter 9
Hydrogen
,Commercial production of Hydrogen
1) Electrolysis of acidified water using platinum electrodes
electrolysis
2H₂O(l) 2H₂(g) + O₂(g)
2) High purity dihydrogen (>99.95%) is obtained by the electrolysis of warm
aqueous Ba(OH)₂ solution using nickel electrodes.
3) By the electrolysis of brine solution (NaCl solution). Here H₂ gas is obtained
at the cathode.
-
At anode: 2Cl (aq) → Cl₂(g) + 2e-
- -
At cathode : 2H₂O (l) + 2e → H₂(g) + 2OH (aq)
Overall reaction is :
2NaCl (aq) + 2H₂O (l) → Cl₂(g) + H₂(g) + 2NaOH (aq)
, ▪
4) By the reaction of steam on hydrocarbons or coke at high temperature in the
presence of catalyst. 1270K
CH₄(g) + H₂O(g) → CO(g) + 3H₂(g)
The mixture of CO and H₂ is called water gas / synthesis gas / syn gas.
The process of producing 'syngas' from coal is called 'coal gasification'.
1270K
C(s) + H₂O(g) CO(g) + H₂(g)
The production of dihydrogen can be increased by reacting carbon monoxide of
syngas mixtures with steam in the presence of iron chromate as catalyst.
This is called water-gas shift reaction.
673K
CO(g) + H₂ + H₂O(g) Catalyst CO₂(g) + 2H₂(g)
Hydrogen
,Commercial production of Hydrogen
1) Electrolysis of acidified water using platinum electrodes
electrolysis
2H₂O(l) 2H₂(g) + O₂(g)
2) High purity dihydrogen (>99.95%) is obtained by the electrolysis of warm
aqueous Ba(OH)₂ solution using nickel electrodes.
3) By the electrolysis of brine solution (NaCl solution). Here H₂ gas is obtained
at the cathode.
-
At anode: 2Cl (aq) → Cl₂(g) + 2e-
- -
At cathode : 2H₂O (l) + 2e → H₂(g) + 2OH (aq)
Overall reaction is :
2NaCl (aq) + 2H₂O (l) → Cl₂(g) + H₂(g) + 2NaOH (aq)
, ▪
4) By the reaction of steam on hydrocarbons or coke at high temperature in the
presence of catalyst. 1270K
CH₄(g) + H₂O(g) → CO(g) + 3H₂(g)
The mixture of CO and H₂ is called water gas / synthesis gas / syn gas.
The process of producing 'syngas' from coal is called 'coal gasification'.
1270K
C(s) + H₂O(g) CO(g) + H₂(g)
The production of dihydrogen can be increased by reacting carbon monoxide of
syngas mixtures with steam in the presence of iron chromate as catalyst.
This is called water-gas shift reaction.
673K
CO(g) + H₂ + H₂O(g) Catalyst CO₂(g) + 2H₂(g)
