What Are the Advantages of Dimensionally Stable Anodes Compared with Graphite Anodes?

Aug 15, 2022

What Are the Advantages of Dimensionally Stable Anodes Compared with Graphite Anodes?

Electro-catalyst enables the electron transfer reactions at the electrode-electrolyte interface with substantial energy savings. The total energy consumption in the chloro-alkali process is proportional to the total cell voltage, including the thermodynamic potential of anodic and cathodic reactions, electrode over potential, and an ohmic drop from the electrolyte, membrane, and bubble effect, etc.  

The electrode upon which oxidation occurs in an electrochemical cell is called the “Anode”. The design and selection of the parameters of anodes have traditionally been associated with the optimization of fixed and operating costs of the anode. Most of the materials used in anode fabrication are characteristically expensive. However, higher costs are justified by enhanced
performance and reduced operational costs. An additional consideration in the selection of an appropriate anode is that it should be environment-friendly.

Historically, graphite anodes were commonly employed in the brine electrolysis industry. The use of these anodes was abandoned due to the consumption of graphite anodes during the process.
Moreover, the use of metal phosphides and metal disulfides as electro-catalysts in electrochemical cells, especially with alkaline electrolytes, was also a common practice. Later on, the electro-catalysts based on Platinum and Nickel were developed and the brine electrolysis industry switched over to the use of these Dimensionally Stable Anodes (DSA) with subsequent industrial applications. The combination of innovative techniques like energy-saving membrane cell technology and DSA has since become the most preferred choice in the design and construction of the new Chlor-alkali industry. Dimensionally Stable Anodes (DSA) have the following main advantages compared to that previously used graphite anodes:
Lower power consumption;
Longer anode life;
Stability of electrodes during electrolysis;
Elimination of environmentally harmful materials;
Relatively consistent and stable cell room operation;
Reduction in labor.

Compact and crack-free coatings can be used as a protective inner layer for the fabrication of DSA. Hence, the DSAs are coated with expensive coating materials. The formulation of coating
the solution varies in each case while coating process parameters remain the same. The main types of DSA coatings used in electrochemical industries are:
Ruthenium oxide-based coating;
Iridium oxide-based coatings;
Mixed ruthenium-iridium oxides coatings;
Platinum-Iridium coatings;
Ternary system of coatings.

About 3 tons of Ruthenium per year (12% of the annual production of Ruthenium) is used for the fabrication of anodic electro-catalytic coatings. Ruthenium based electrocatalytic anodes find applications in water electrolysis, electro-organic synthesis, and electrochemical oxidation. Such types of anodes are used in caustic–chlorine cells, chlorate cells, seawater electrolysis, and similar applications.