Glycine-mediated in-situ regeneration of thallium-poisoned commercial V2O5-WO3/TiO2 catalysts

Abstract

The highly toxic metal thallium (Tl) poses significant hazards to commercial V₂O₅-WO₃/TiO₂ catalysts. However, the efficient regeneration of Tl-poisoned V₂O₅-WO₃/TiO₂ catalysts remains a considerable challenge. This study collects Tl-poisoned commercial V₂O₅-WO₃/TiO₂ catalyst from the cement industry, and systematic analyses reveals that Tl exhibits strong penetrability, severely covering acid sites and drastically reducing NH₃ adsorption capacity. An in-situ glycine leaching regeneration method was developed to restore the activity of Tl-poisoned V₂O₅-WO₃/TiO₂ catalysts. The specific coordination ability of glycine facilitates the selective removal of Tl. The coordination mode between glycine and Tl⁺ is modulated by introducing H⁺, significantly enhancing the coordination capacity for Tl⁺, thereby facilitating the deep removal of Tl, with a leaching efficiency of 90.19 %. Moreover, glycine effectively reconstructs the vanadium active sites, and substantially restores the redox properties and surface acidity of the catalysts. The regenerated catalyst exhibits catalytic activity comparable to that of the fresh catalyst. Additionally, Tl⁺ leached by glycine is successfully recovered as TlCl. This study provides new insights into the poisoning mechanism of Tl in commercial V₂O₅-WO₃/TiO₂ catalysts and develops a one-step in-situ regeneration technology with potential for industrial application.