The chemical industry for the production of chlorine and caustic soda by electrolysis of salt (NaCl) water melt is known as the chlor-alkali industry. It is the modern electrochemical industry known as the chlor-alkali industry and it is the largest sector in the modern electrochemical industry. The chlor-alkali industry's products—chlorine, hydrogen and caustic soda—are basic chemical raw materials and are widely used in chemical, petrochemical, metallurgy, light industry, textile, and civil sectors.
The key to electrolysis of chlorine solution and caustic soda by brine solution is to separate the yin and yang bipolar products in the electrolyzer. Otherwise, various side reactions and secondary reactions will occur, which will greatly reduce the yield and product quality, and may explode. According to the product separation method, the chlor-alkali industry has developed two different production processes, namely diaphragm electrolysis and mercury electrolysis.
1. Membrane Electrolysis Method The diaphragm electrolysis method separates the anode and cathode regions with a porous membrane to avoid the mixing of the bipolar products. Diaphragm electrolytic cell began to use carbon anode, high pressure and high loss slot, after the advent of metal anodes, applied to the chlor-alkali industry, the chlor-alkali industry made a breakthrough, the metal anode coating available RuTi, RuSnTi, RuIrTi and so on.
2. Ion-membrane electrolysis The ion-membrane electrolysis method not only has the advantages of high product quality and low energy consumption, but also eliminates the pollution and environmental pollution caused by mercury using the asbestos and mercury methods of the diaphragm method. Membrane electrolyzers use metal anodes, while cathodes use active cathodes that reduce hydrogen evolution overpotentials.
Compared with the graphite electrode, the diaphragm method produces caustic soda, and the operating voltage of the graphite anode is 8A/DM2. The coated anode can be doubled, reaching 17A/DM2. In this way, the product can be exponentially increased in the same electrolytic environment, and the quality of the produced product is high, and the purity of chlorine is high.
Electrochemical Performance of Niobium Titanium Coated Metal Anodes in Chlor-Alkali Industrial Electrolyzers
1. The discharge overpotential of chlorine on the niobium titanium anode is significantly lower than that on the graphite anode.
2. The oxygen release potential of the barium titanium coating is also low.
3. Strong corrosion resistance and long working life.