By-Product of Chemical Production Processes

Various chemical processes do produce hydrogen as a by-product. Hydrogen is a by-product of sodium or potassium chloride electrolysis that produces chlorine and caustic soda or potash  

Chlorine is one of the most common chemicals in the world. It is produced in huge quantities. Hydrogen is a by-product of catalytic reforming of petrol, made to improve the octane number. It is also a by-product of steam cracking of hydrocarbons for the production of ethylene. This hydrogen is used in other refinery operations. Smaller volumes of hydrogen are by-products in coke ovens and usually are kept for internal use. All by-product hydrogen requires some purification steps before use. 

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