Studies on the Oxide‐Coated Metal Anodes for Chlor‐Alkali Cells

Abstract

Formation of the mixed oxide consisting of RuO2 and TiO2 was studied by the DTA/TGA technique and x‐ray diffraction. The coating agent containing RuCl3 and tetra‐n‐butyl titanate converted into the mixed oxide of RuO2 and TiO2 at about 400°C on the Ti substrate, and the reaction was exothermic. The electric resistance through the oxide film depends much on the fire temperature, and an optimum condition arises between 450° and 500°C. The solution composition and the time of preparation are also important factors. The anodic polarization behavior in the normalNaCl solution was also affected by the material or the condition of preparation of the oxide‐coated Ti electrode.

Problems in DSA� coating deposition by thermal decomposition

“…This has already been suggested for Ru-Ti coatings [15]. To see if the fact of dissolving the salt alters the thermogravimetric properties of the compound, we recorded the therrnograms of pure HzPtCt6-6HzO and TiCt3 (Figs 5 and 6).…”

“…the coating deposition procedure by brush is reproducible from tayer to layer. On the other hand from electrode to electrode, the experimental error is between 15 Table 1. [3,4].…”

“…In the field of DSA | electrode preparation, knowledge is a matter of experience and usually the preparation procedure given either by early publications or directly by a manufacturer is followed. But originally (for Ru see [14,15]), the annealing temperatures were determined by thermogravimetric measurements of the single metal chloride, which give the temperatures of the different decomposition steps. It was found that the most common salts (of Ru, Ir, Ti, Pt, Ta) need the temperature range 350 ~ to 500 ~ C. When a new compound is chosen, its thermal behaviour should be determined, in order to find the most appropriate annealing temperature.…”

Electrochemical treatment of aqueous solutions containing urea

“…The Ti/Pt electrode was made by Pt electrodeposition [41][42][43]. The Ti/(RuO 2 -TiO 2 ) 60:40 electrodes were prepared by thermal decomposition of appropriate salts on titanium [44][45][46]. Solutions were agitated by gases evolving on the electrodes.…”

Structural analyses of RuO2–TiO2/Ti and IrO2–RuO2–TiO2/Ti anodes used in industrial chlor-alkali membrane processes

“…After the development of the DSA ® [1], both fundamental and applied researches have been carried out as reviewed by Trasatti [2][3][4]. For instance, industrial applications for chlor-alkali processes [5][6][7][8][9][10][11]; the form of Ti substrates (e.g., nets, meshes, expanded metals) of the DSA ® s used in industry [8][9][10][11]; the optimum chemical composition such as RuO 2 (30%)-TiO 2 (70%)/Ti [12][13][14]; recommended preparation temperature (e.g., 400~500°C for RuO 2 -TiO 2 /Ti) [13,15]; surface area (roughness factor) of oxide electrodes such as IrO 2 -RuO 2 /Ti electrodes [16][17][18]; observation of the mud-cracks by scanning electron microscopy [19,20]; effect of the preparation conditions on the formation of solid-solution (e.g., RuO 2 -TiO 2 /Ti) [21,22] …”