Preparation of high purity ruthenium nitrosyl nitrate from spent Ru-Zn/ZrO₂ catalyst

Preparation of high purity ruthenium nitrosyl nitrate using spent Ru-Zn/ZrO₂ catalyst was studied, including melting and leaching to obtain potassium ruthenate solution, reduction, dissolving, concentrating and drying to obtain ruthenium trichloride, nitrosation and hydrolysis to obtain ruthenium nitrosyl hydroxide, removing of K⁺ and Cl⁻, and neutralization with nitric acid. The effects of temperature, concentration, time and pH on the yield and purity of intermediates and final product were studied, and the optimum process conditions were obtained. The yield of ruthenium nitrosyl nitrate is 92%, the content of ruthenium in high purity product is 32.16%, and the content of Cl⁻ and K⁺ are much less than 0.005%. The reaction kinetics of ruthenium nitrosyl chloride to ruthenium nitrosyl hydroxide was studied. The reaction orders of Ru(NO)Cl₃ at 40, 55 and 70 °C are 0.39, 0.37 and 0.39, respectively, while those of KOH are 0.16, 0.15 and 0.17, respectively. The activation energy is −2.33 kJ/mol.