Unraveling the role of carbon coating on CoSe2 to enhance elemental mercury removal from smelting flue gas

Metal selenides have been demonstrated as promising Hg 0 adsorbents, while their poor high temperature activity impedes their application feasibility in non-ferrous smelting flue gas. Herein, highly well-dispersed CoSe 2 nanoparticles were immobilized on the inner of carbon layer via an in-situ carbon coating strategy, consequently demonstrating improved Hg 0 removal performance. Compared to CoSe 2 , CoSe 2 /NC exhibited remarkably higher mercury removal activity, which may be attributed to more active sites (Co 3+ , Se 2 2- ) exposed between carbon interfaces and CoSe 2 . More significantly, CoSe 2 /NC with a moderate carbonization temperature of 500℃ could maintain its stable Hg 0 removal activity at a wide operating temperature range (60–240 °C). The saturation adsorption capacity of CoSe 2 /NC-500 could achieve 510.48 mg·g −1 at 180 °C. The outstanding adsorption activity at elevated temperature is mainly attributed to the thermostability of active Se species immobilized in the carbon layer by both space constraint and chemical interaction, leading to the enhanced mercury diffusion migration energy barrier from 0.41 to 0.79 eV on CoSe 2 . The present study aims to take an important step toward the rational design of selenium-based adsorbents for mercury removal from nonferrous smelting flue gas through the excellent protective properties of carbon coating.