Chlor-alkali industry is one of the most basic chemical industries. Its products are widely used in light industry, textile, metallurgy, petrochemical industry and public utilities other than chemical industry. Its production and development have a great impact on the national economy. Titanium is widely used in the chlor-alkali industry. First, it has excellent corrosion resistance to wet chlorine and sodium chloride solutions. Titanium is more resistant to chloride ion corrosion than commonly used stainless steel and other non-ferrous metals. Second, its electrochemical properties are suitable for use as anode materials.
Titanium has a melting point of 1680°C and a density of 4.54g/cm3. It is heavier than aluminum, but 43% lighter than steel. Titanium has high strength, which is 6 times that of aluminum. Therefore, among structural materials, titanium has a very high specific strength. Another biggest advantage of titanium is that it has strong corrosion resistance to many substances. Titanium has strong corrosion resistance, because it has a particularly high affinity for oxygen, and a dense oxide film will be formed on the surface to protect titanium from corrosion by the medium. Titanium can form a passive oxide film on the surface in most aqueous solutions. Therefore, titanium has good stability in acidic, alkaline, neutral salt solutions and oxidizing media, and its corrosion resistance is superior to existing stainless steel and other non-ferrous metals, and even comparable to platinum. At present, titanium is widely used in the manufacture of metal anode electrolyzers, ionic membrane electrolyzers, wet chlorine coolers, refined brine preheaters, dechlorination towers, and chlorine gas cooling scrubbers in the chlor-alkali industry. In the past, most of these main components and equipment types were non-metallic materials (such as graphite, polyvinyl chloride, etc.). Due to the unsatisfactory mechanical properties, thermal stability and processing properties of non-metallic materials, it seriously affects the quality of subsequent products and pollutes the environment. Therefore, since the 1970s, the chlor-alkali industry has successively replaced graphite electrolyzers with metal anode electrolyzers and ionic membrane electrolyzers, and replaced graphite coolers with titanium wet chlorine coolers, all of which have achieved good results. The United States began to manufacture chlor-alkali equipment as early as the 1960s, and this application has developed rapidly, with a compound annual growth rate of 8%. In 2021, around 50% of the world’s chlorine production uses anodes coated with ruthenium-titanium. In the production of chlorine in Russia, more than 80% of the equipment and pipelines are made of titanium. The entire chlor-alkali industry, the production of chlorine and other oxides, toxic chemicals, chloramines and bleaching powders, accounts for more than 60% of the chemical sector’s use of titanium equipment. In the chlor-alkali industry, Japan uses titanium anodes, which are the most widely used titanium products in Japan. Since the early 1980s, China’s chlor-alkali industry has used titanium anodes and achieved good economic results.
The use of titanium metal anodes and titanium wet chlorine coolers in the chlor-alkali industry has achieved good economic benefits, and is known as a major revolution in the chlor-alkali industry.