Chlorherstellung mit Sauerstoffverzehrkathoden. Energieeinsparung bei der Elektrolyse

Chlorine is one of the most important base chemicals and is required for the manufacture of about two‐thirds of all chemical products such as polymers, crop protection and pharmaceutical products, products for drinking water purification, and ultrapure silicon for photovoltaics and electronics applications. The industrial chlorine production through the chlor‐alkali electrolysis has since 1975 mainly been based on the advanced membrane process. Chlorine recycling by manufacturing processes based on hydrogen chloride has also become increasingly important. The still very high energy demand for the electrochemical chlorine synthesis can be significantly reduced by up to 30 % if the hydrogen evolving cathodes in the classical processes are replaced by oxygen depolarized cathodes (ODC) which are well known from fuel cells. Hydrogen chloride electrolysis with ODCs is already carried out in world‐scale plants. The more important chlor‐alkali process with ODCs will be realized for the first time in 2011 in a demonstration unit with a chlorine capacity of 20000 tons per year in Uerdingen, Germany.