THERMAL DECOMPOSITION OF RHODIUM IRIDIUM AND RUTHENIUM CHLORIDES

The decomposition of rhodium, indium, and ruthenium chloride hydrates in air and in hydrogen have been studied by means of thermogravimetric analysis; additional studies have been made of their reduction when dispersed on low- and high-area substrates. Under the conditions used, reduction to metal is complete at 105 °, 190 °, and ~ 350 ° for the Rh, Ir, and Ru salts, respectively. In air, dechlorination and oxidation are complete at 890 °, 680 °, and ~ 440 °, respectively. Boron carbide, a low-area substrate, appears to exert little influence on the reduction temperature of the rhodium salt, whereas with alumina, a high-area support, desorption of decomposition products may be the cause for the slower rate of weight loss observed with all three salts. © 1968.