Question

Answer the following question.

Outline the industrial production of dihydrogen from steam. Also, write the chemical reaction involved.

Answer 1

Three stages are involved in the industrial production of dihydrogen from steam.

1. Stage 1:
   a. Reaction of steam on hydrocarbon or coke (C) at 1270 K temperature in presence of nickel catalyst gives water-gas which is a mixture of carbon monoxide and hydrogen.
   1.Reaction of steam with hydrocarbon:
   \[\ce{\underset{\text{Methane (Hydrocarban)}}{CH4_{(g)}}+\underset{\text{Steam}}{H2O_{(g)}}->[1270K][Ni]\underset{\text{Water-gas (syngas)}}{CO_{(g)} + 3H2_{(g)}}}\]
   2. Reaction of steam with coke or carbon (C):
   \[\ce{C_{(s)} + H2O_{(g)}->[1270K][Ni]CO_{(g)} + H2_{(g)}}\]
   b. Sawdust, scrap wood, etc. can also be used in place of carbon.
2. Stage 2: Water-gas shift reaction:
   When carbon monoxide in the water-gas reacts with steam in the presence of iron chromate (FeCrO₄) as a catalyst, it gets transformed into carbon dioxide. This is called water-gas shift reaction.
   \[\ce{\underset{\text{Carbon monoxide (from syngas mixture)}}{CO_{(g)}} + \underset{\text{Steam}}{H2O_{(g)}}->[673K][Iron chromate catalyst]\underset{\text{Carbon dioxide}}{CO2_{(g)}} + \underset{\text{Hydrogen}}{H2_{(g)}}}\]
3. Stage 3: In the last stage, carbon dioxide is removed by scrubbing with sodium arsenite solution.