Preparation of water gas

Preparation of water gas :

Water gas is a mixture of carbon monoxide and hydrogen.

water gas formula is  \text{C + H}_{2} \text O  \longrightarrow  \text {H}_{2} + \text {CO}

Principle : In the preparation of water gas superheated steam is passed over white-hot coke. A mixture of \left ( \text { CO +H}_{2}\right ) is obtained.

Procedure : The generator is filled with coke. It is provided with coke – inlet at the top and two side tubes in the bottom. One tube is for sending steam and another for sending hot air. Thus, alternately hot air and steam are blown into the generator.

When superheated steam is passed over white-hot coke, a mixture of CO and \text H_{2} is obtained.

\text {C + H}_{2} \text O \longrightarrow \text {CO + H}_{2} \,; \Delta \text {H = + 121.22 kJ/mole.}

The above reaction is endothermic. The temperature of the coal comes down. So, alternately hot air is passed over the coke.

\text {C + O}_{2} \longrightarrow \text {CO}_{2} \, ;\Delta \text {H = - 394 kJ/mole.}

\text {CO}_{2} formed in the reaction is allowed to escape out. Being the reaction exothermic, the temperature increases.

When the supply of air is stopped, steam is passed over hot coke and now water gas is produced.

Water gas preparation

Uses of water gas :

  • The calorific value of water gas is higher i.e., 13,000 kJ/\text m^{3}. Hence it is extensively used as a fuel in industries.
  • It is used in the manufacturing of Ammonia by Haber’s process as a source of \text H_{2}.
  • Semi water gas and carbureted water gas are prepared from water gas to use it in steel industry (or) in internal combustion engines.