Тұздықтың электролизі арқылы хлор және сіңіргіш натрий өндірісі

Industrial process for electrolysis of sodium chloride

The chloralkali process (also chlor alkali and chlor alkali) is an industrial process for the electrolysis of sodium chloride (NaCl) solutions. It is the technology used to produce chlorine and sodium hydroxide (caustic soda), which are commodity chemicals required by industry. Thirty five million tons of chlorine were prepared by this process in 1987. The chlorine and sodium hydroxide produced in this process are widely used in the chemical industry. Usually the process is conducted on a brine (an aqueous solution of NaCl), in which case sodium hydroxide (NaOH), hydrogen, and chlorine result. When using calcium chloride or potassium chloride, the products contain calcium or potassium instead of sodium. Related processes are known that use molten NaCl to give chlorine and sodium metal or condensed hydrogen chloride to give hydrogen and chlorine. The process has a high energy consumption, for example around of electricity per tonne of sodium hydroxide produced. Because the process yields equivalent amounts of chlorine and sodium hydroxide (two moles of sodium hydroxide per mole of chlorine), it is necessary to find a use for these products in the same proportion. For every mole of chlorine produced, one mole of hydrogen is produced. Much of this hydrogen is used to produce hydrochloric acid, ammonia, hydrogen peroxide, or is burned for power and/or steam production.

Due to the corrosive nature of chlorine production, the anode (where the chlorine is formed) must be non reactive and has been made from materials such as platinum metal, graphite (called plumbago in Faraday's time), A mixed metal oxide clad titanium anode (also called a dimensionally stable anode) is the industrial standard today. Historically, platinum, magnetite, lead dioxide, manganese dioxide, and ferrosilicon (13–15% silicon) have also been used as anodes. Platinum alloyed with iridium is more resistant to corrosion from chlorine than pure platinum. Unclad titanium cannot be used as an anode because it anodizes, forming a non conductive oxide and passivates. Graphite will slowly disintegrate due to internal electrolytic gas production from the porous nature of the material and carbon dioxide forming due to carbon oxidation, causing fine particles of graphite to be suspended in the electrolyte that can be removed by filtration. The cathode (where hydroxide forms) can be made from unalloyed titanium, graphite, or a more easily oxidized metal such as stainless steel or nickel.

The interests of chloralkali product manufacturers are represented at regional, national and international levels by associations such as Euro Chlor and The World Chlorine Council.