Once the process of Hydrogen production is complete, the Hydrogen gas formed has to be purified so that it can be used for industrial purposes. Therefore, Hydrogen Purification is the next step. In this process,  Catalytic Purification removes oxygen by reaction with hydrogen to form water.  A mixture of gases is passed through a packed column of molecular sieves. Then, the hydrogen is absorbed, while the undesired particles are let out.  The column is regenerated by the system, and the cycle continues. 

Also, there is another process called Hydrogen Recovery. As the name suggests, it is the recovery of Hydrogen from Hydrogen-rich raw gasses. 

There are three common methods to do this: 

Cryogenic hydrogen recovery :

The gas mixture is cooled to the point that the non-hydrogen components drop out as a liquid. 

Pressure Swing adsorption (PSA) :

The gas mixture is passed through a molecular sieve solid adsorbent. 

Membrane diffusion :

The gas mixture is separated by using pressure to force the hydrogen through a membrane that is hydrogen-permeable.

To know more about the various processes involved in the production of Hydrogen, click here.