EARTH

[3901-12-11] Recovery of tungsten and vanadium from spent V₂O₅-WO₃/TiO₂ catalysts

○In-hyeok - Choi^1,2, Hee-nam Kang², Rajesh Kumar Jyothi^2,1, Jin-Young Lee^2,1 (1. Korea University of Science and Technology, 2. Korea Institute of Geoscience and Mineral Resources)

Chairman: Kyoungkeun Yoo （Korea Maritime and Ocean University）, Naoki Hiroyoshi (Hokkaido University)

Keywords:spent SCR catalyst, recycling, vanadium, tungsten, separation

Nitrogen oxide (NO_x), which is the byproduct of high-temperature combustion in stationary applications, is unwanted pollutants in the atmosphere, and controlling it by the Selective Catalytic Reduction (SCR) catalyst is of major environmental interests. The most commercial SCR catalyst in the world has been considered as V₂O₅-WO₃/TiO₂ catalyst due to its high NO_x conversion rate, durability from poison, sulfur resistance, wide operation window. SCR catalyst was given a finite life due to abnormal operations, contaminations, and degradation of catalytic performance. Typical lifetime was approximately three years depending on the composition. However, regeneration process such as chemical washing and soot blowing can prolong the another typical lifetime. Nevertheless, degradation of catalytic performance cannot be prevented since properties such as texture, porosity and structure of SCR catalyst is damaged by physical and chemical treatments. Thus, the occurrence of completely abandoned spent SCR catalysts is unavoidable. Unfortunately, a considerable amount of spent SCR catalysts has been treated as a specific waste and disposed of in landfills. Moreover, the related study had been seldom investigated. Considering the industrial importance and environmental burdens, recovery of metal values such as vanadium and tungsten from spent SCR catalyst as an another valuable secondary source should be established. This study deals with the proposal for the recovery process of metal values (V, W) from the spent V₂O₅-WO₃/TiO₂ catalyst by in order of alkali fusion, leaching, selective precipitation.