The role of metal oxide coatings on titanium anodes
Titanium anode is the anode in titanium-based metal oxide coating. According to the different surface catalytic coatings, it has the function of oxygen evolution and chlorine evolution respectively. Generally, electrode materials should have good electrical conductivity, small change in pole distance, strong corrosion resistance, good mechanical strength and processing performance, long life, low cost, and good electrocatalytic performance for electrode reaction. At present, titanium is the most suitable for the above Generally, industrial pure titanium TA1TA2 is used for the metal required by the comprehensive requirements. The role of the metal oxide coating on the titanium anode is: low resistivity, good electrical conductivity (titanium itself has poor electrical conductivity), and the chemical composition of the precious metal coating is stable. The crystal structure is stable, the electrode size is stable, the corrosion resistance is good, the service life is long, and the electrocatalytic performance is good.
1. Titanium anode has a long working life. In the chlor-alkali industry produced by the diaphragm method, the metal anode is resistant to chlorine and alkali corrosion. The anode life has reached more than 6 years, while the graphite anode is only 8 months.
2. It can overcome the dissolution problem of graphite anode and lead anode, avoid the pollution of electrolyte and cathode products, and thus improve the purity of metal products.
3. It can increase the current density. In the production of chlor-alkali by the diaphragm method, the working current density of the graphite anode is 8A/dm2, and the titanium anode can be doubled to 17A/dm2. In this way, under the same conditions of the electrolysis plant and the electrolytic cell, the output can be doubled, which improves the The single-slot production capacity effectively improves labor productivity. When electrolysis is performed at high operating current densities, it is more appropriate to use titanium anodes.
4. Due to the use of metal anodes, high temperature and high current density operation of chlorate electrolytic cells is possible. The use of metal anodes improves the electrolytic cell structure, reduces power consumption, and accelerates the chemical reaction of hypochlorite to generate chlorate, thereby improving production performance.
5. By adopting DSA, the design concept and operating conditions of the mercury-method and diaphragm-method salt electrolyzers are improved, and the energy consumption is reduced. The low overpotential characteristics of DSA and the easy removal of air bubbles on the surface between electrodes and electrodes are the important reasons for the reduction of the voltage of the metal anode electrolytic cell. Due to the many advantages of titanium anode, its development has made the chlor-alkali industry obtain great economic benefits, so it will soon be popularized and used all over the world. The production capacity of chlor-alkali is about 41 million tons/year in the world, and the titanium anode is not less than 70%. Titanium anode is known as a major technology in the chlor-alkali industry. Subsequently, titanium anodes have also been widely used in many electrolysis industries.
6. The anode size is stable, and the distance between electrodes does not change during the electrolysis process, which can ensure that the electrolysis operation is carried out under the condition of stable cell voltage.
7. It can avoid the short circuit problem after the lead anode is deformed, so it can improve the current efficiency.
8. Titanium anode is light in weight, which can reduce labor intensity.
9. The switch is easy to make and can be high-precision.
10. The working voltage is low, so the power consumption is small, which can save power consumption, and the DC power consumption can be reduced by 10% to 20%. The main reasons for the low working voltage of titanium anode:
1) The overpotentials of active-coated titanium anodes to chlorine and oxygen are relatively low. When salt water electrolysis produces chlor-alkali, the titanium anode has a low chlorine overpotential, which is 140mV lower than that of the graphite anode at 1A/cm2;
2) It can reduce the "bubble shielding effect", the bubbles generated on the surface of the metal anode are relatively small, and the detachment is rapid, so that the aeration between the electrodes is greatly reduced, the ohmic drop between the two electrodes is about 700mV, and the diameter of the bubbles is about 3mm;
3) Reduce the resistance of the anode structure;
4) The distance between poles is shortened. In the 1960s, the annual electricity consumption of the salt electrolysis industry in the world was about 150 billion kWh. After using metal anodes, about 300 million kWh of electricity can be saved every year.
11. In chlor-alkali production, after using titanium anode, the product has high quality, high purity, no CO2, high alkali concentration, which can save heating steam and energy consumption.
12. It has strong corrosion resistance and can work in many electrolytic media with strong corrosiveness and special requirements.
13. The base metal titanium can be used repeatedly.
14. With the emergence of metal anodes, the latest ionic membrane electrolysis technology that has recently emerged in the chlor-alkali industry can be designed and industrialized. Soluble anodes and insoluble anodes Soluble anodes supplement metal ions and conduct electricity during electrolysis, while insoluble anodes only conduct electricity. The earliest insoluble anodes were graphite and lead-based anodes. In the 1970s, titanium anodes began to be used in electrolysis and electroplating as a new technology. At present, insoluble anodes can be divided into two categories: chlorine evolution anodes and oxygen evolution anodes. Chlorine evolution anode is mainly used in chloride electrolyte system. During the electroplating process, the anode has *shielded keywords* released, so it is called chlorine evolution anode; oxygen evolution anode is mainly used for sulfate, nitrate, hydrocyanate, etc. In the electrolyte system, oxygen is released from the anode during the electroplating process, so it is called an oxygen evolution anode. Lead alloy anodes are oxygen-evolution anodes, and titanium anodes have oxygen-evolution, chlorine-evolution functions or both according to their surface catalytic coatings.
Titanium anode for chlor-alkali industry Compared with graphite electrode, the diaphragm method produces caustic soda. The working voltage of graphite anode is 8A/DM2, which can be doubled to 17A/DM2. In this way, the products can be doubled under the same electrolysis environment, and the quality of the products produced is high, and the purity of the shielded keywords is high. Titanium anode for electroplating The insoluble anode for electroplating is to coat the titanium substrate (mesh, plate, ribbon, tube, etc.) with a noble metal oxide coating with high electrochemical catalytic performance, and the coating contains high stability valve Metal oxide. The new insoluble titanium anode has high electrochemical catalytic energy, and the oxygen evolution overpotential is about 0.5 V lower than that of the lead alloy insoluble anode. The oxygen evolution overpotential of the new insoluble titanium anode is also lower than that of the platinum-plated insoluble anode, but the life span is more than doubled. It is widely used as anode or auxiliary anode in various electroplating, and can replace conventional lead-based alloy anode. Under the same conditions, it can reduce cell voltage and save power consumption; insoluble titanium anode has good stability in the electroplating process. (chemical, electrochemical), long service life. This anode is widely used in nickel-plated gold-plated, chrome-plated, zinc-plated, copper-plated and other electroplating non-ferrous metal industries.
