Study on kinetics of vanadium leaching from waste denitrification catalyst with mixed acid
Due to long-term operation in high-temperature flue gas of thermal power plants,the activity of vanadium titanium-based denitration catalyst gradually decreases with the extension of operating time,and their service life is generally 3～4 years. About 60％ of these denitration catalyst are affected by factors such as physical structure damage and mechanical performance degradation,and therefore do not have regeneration value and need to be scrapped. Extracting valuable metal elements from them is an important way to achieve efficient resource utilization of spent denitration catalyst. This study proposes a technical route for recovering vanadium from spent denitration catalyst using inorganic-organic combined solvent. The kinetic model during the leaching process was analyzed,and the entire process of recovering vanadium and support from spent denitration catalyst was formed. Kinetic analysis was studied on the leaching vanadium based on the optimal process conditions of sulfuric acid-oxalic acid combined solvent. The research method of macroscopic dynamics was adopted to explore the chemical reaction control of the leaching process. The results showed that the process of leaching vanadium from spent denitration catalyst with sulfuric acid-oxalic acid combined solvent was a typical liquid-solid non-catalytic reaction,and the kinetic model was an unreacted core reduction model. The kinetic control type of vanadium during the leaching process is surface chemical reaction control,which can be fitted by the kinetic equation. The linear correlation coefficient of the fitted line is greater than 0.98 and the activation energy of this process is 4.53 kJ/mol.
mixed acid synergisticspent deNOx catalystkinetics of vanadium leaching
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