Efficient removal of thallium from flow gas using manganite‐based catalysts by gas–solid‐phase catalytic oxidation at low temperature

Abstract

Thallium (Tl) is a highly toxic heavy metal, for which its removal from aqueous environments has gained increasing attention. However, removal of Tl from the gas phase is yet to be addressed, especially at low temperature. Herein, we synthesized and characterized a manganite‐based active carbon (Mn–AC) catalyst via an impregnation method process. The Mn–Ac catalyst was then used for elemental Tl removal from simulated flow gas in a laboratory‐scale fixed‐bed reactor. Tl(I) was adsorbed by the AC and oxidized by active Mn, resulting in Tl(III). In addition, experiments were performed at varying temperatures and different Mn dosages to evaluate the efficiency of Tl removal in various conditions. The Mn–AC catalysts were shown to oxidize Tl(I) to Tl(III) on their surface with Tl removal efficiency decreasing with increasing temperature, reaching a removal rate of 90% over 8 h at 25°C. Further, increasing Mn content led to a decrease in surface area and a convolution of the AC morphology. Mn(10%)–AC was shown to have the highest gas‐phase Tl removal efficiency (≥90%, over 8 h).