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 (O-2, 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 Hg-0 removal efficiency, Hg0 removal capacity, and difference ratio of Hg-0 removal capacity (anti-interference ability) in the basic and full-component simulated flue gas atmosphere (N-2 + O-2 + CO2, N-2 + O-2 + 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. O-2, 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 O-2 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 O-2. TSC-21 acts more as an oxidant than an adsorbent for Hg0 removal.

Automated summary

This study characterizes and analyzes the effects of coal-fired flue gas components on the removal of Hg0 using a promising mercury removal adsorbent. The results show that mechanochemical S-modified petroleum coke with a theoretical sulfur content of 21% exhibits the best performance for mercury removal. O2, CO2, and NO promote the removal of Hg0, but also inhibit its adsorption. The presence of SO2 inhibits the oxidation and adsorption of Hg0, resulting in reduced removal performance.