Effects of Coal-Fired Flue Gas Components on Mercury Removal by the Mechanochemical S-Modified Petroleum Coke

In this work, the effects of coal-fired flue gas components (O₂, CO₂, SO₂, and NO) on the Hg⁰ removal by the promising mercury removal adsorbent mechanochemical S-modified petroleum coke were characterized and analyzed in terms of the Hg⁰ removal efficiency, mercury adsorption capacity, and mercury mass balance. The results show that the mechanochemical S-modified petroleum coke with a theoretical sulfur content of 21% (named TSC-21) is the best candidate for mercury removal based on the Hg⁰ removal efficiency, Hg⁰ removal capacity, and difference ratio of Hg⁰ removal capacity (anti-interference ability) in the basic and full-component simulated flue gas atmosphere (N₂ + O₂ + CO₂, N₂ + O₂ + CO₂ + SO₂ + NO). The maximum value (MV) and stable value (SV) of the Hg⁰ removal efficiency of TSC-21 in the basic simulated flue gas atmosphere are 99.25% (MV) and 91.17% (SV), respectively. O₂, CO₂, and NO all promote the Hg⁰ removal by the adsorbent, but they benefit the Hg⁰ oxidation while inhibiting the Hg⁰ adsorption. The promoting effect of O₂ on the Hg⁰ removal by TSC-21 is affected by the reaction time, which is especially obvious after 1 min. The presence of SO₂ inhibits the oxidation and adsorption of Hg⁰, which in turn reduces the Hg⁰ removal performance of the adsorbent. The improving effects on the oxidative escape of Hg⁰ by CO₂ is higher than that by NO and O₂. TSC-21 acts more as an oxidant than an adsorbent for Hg⁰ removal.