(BAT) Reference Document for the Production of Chlor-alkali ...

Chapter 1
1.3 Techniquesologies in use
The main techniquesologies applied for chlor-alkali production are mercury, diaphragm and
membrane cell electrolysis, mainly usually using sodium chloride as feed or to a lesser extent
using potassium chloride for the production of potassium hydroxide. Other electrochemical
processes in which chlorine is produced include the electrolysis of hydrochloric acid and the
electrolysis of molten alkali metal and alkaline earth metal chlorides, in which the chlorine is a
byco-product. In 2010, these accounted for less than 3 % of the total chlorine production
capacity in EU-27 and EFTA countries. Additionally, two plants in Germany produce
alcoholates and thiosulphates together with chlorine via the mercury cell technique [ 9, Euro
Chlor 2011 ].
Apart from electrochemical processes, chlorine may also be produced via chemical routes such
as the catalytic oxidation of hydrochloric acid with oxygen (the Deacon process). On account of
the corrosive nature of the involved chemicals and the elevated temperature and pressure,
expensive materials must be used. A commercial plant is reported to have been producing 60 kt
of chlorine per year in Japan since 1990 [ 1, Ullmann's 2006 ] while BASF in Antwerp put a
new plant in operation in 2011 which uses a ruthenium catalyst.
Table 1.1 shows the distribution of the chlorine production processes in west European
countries, indicating the number of installations and the annual capacity of chlorine production.
Table 1.1: Distribution of processes and capacities of chlor-alkali plants in western
Europe (June 2000)
[Euro Chlor] {The complete table with all installations and production capacities was moved to
the Annex.}
Where caustic soda production is concerned, an alternative route to the electrolysis of sodium
chloride is the lime-soda process. In 2011, Today, this process is generally not considered as a
profitable operation in Europe compared with the electrolysis of sodium chloride. One plant in
Romania is reported to use the lime-soda process [ 223, ICIS Chemical Business 2010 ]. The
situation seems to be different in the US, where mineral deposits of natural sodium carbonate
exist. In 2000, this process accounted for 1 – 2 % of the total world capacity of caustic soda
[ 10, Kirk-Othmer 2002 ].
Until the end of the twentieth century, the mercury cell technique dominated in Europe, while
the diaphragm cell technique dominated in the US and the membrane cell technique in Japan.
This pattern has, however, changed during the first decade of the 21st century. Since 1984 no
new plants based on the mercury cell technique have been built, and only a few diaphragm cell
plants have been. All new plants, including those erected in India and China, are based on the
membrane cell technique which is a state-of-the-art technique, both in economic and ecological
terms [ 1, Ullmann's 2006 ].
In EU-27 and EFTA countries, the share of the mercury and diaphragm cell techniques roughly
halved from 1997 to the beginning of 2011, while the share of the membrane cell technique
more than quadrupled from approximately 11 % to 53 % (Figure 1.5). Reasons for the change
include the need to replace installations which have reached the end of their service life and
environmental concerns over mercury emissions from mercury cell plants.
WORKING DRAFT IN PROGRESS
6 December 2011 TB/EIPPCB/CAK_Draft _1