Abstract
Simultaneous removal of Hg0 and H2S over a regenerable activated coke supported Fe2O3 catalyst (Fe2O3/AC) was studied in simulated coal-derived syngas. It was found that the Fe2O3/AC catalyst exhibited high capability for Hg0 and H2S removal, which was attributed to the catalytic oxidation activity of Fe2O3. Its capability for Hg0 and H2S removal increased with an increase of Fe2O3 loading amount, and the highest was at 150 °C for Hg0 removal. CO and H2 showed no obvious effect on Hg0 removal by Fe2O3/AC, while H2S had a promotion effect, which was due to S and FeSx produced by the H2S reaction on Fe2O3/AC. The results of SEM-EDX and the temperature programmed desorption experiment (TPD) revealed that Fe2O3 played a critical role in Hg0 oxidation, and HgS was generated upon the reaction of Hg0 with H2S on Fe2O3/AC. The used Fe2O3/AC catalyst after Hg0 and H2S removal could be effectively regenerated and still had high capability for Hg0 and H2S removal.
Highlights
Mercury in coal can release into the atmosphere during coal conversion processes and cause serious harm to human health and ecological environments due to its toxicity, bioaccumulation, and persistence [1,2]
It was reported that the total Hg concentration in coal gasification syngas was higher than that in coal combustion flue gas, and Hg0 was the dominant form in syngas, accounting for 93–99% [8–11]
The amounts of Hg adsorbed by Fe2O3/activated coke (AC) catalyst and AC were measured by following the Chinese national standard, GB/T 16659-1996, in which the Hg0-adsorbed
Summary
Mercury in coal can release into the atmosphere during coal conversion processes and cause serious harm to human health and ecological environments due to its toxicity, bioaccumulation, and persistence [1,2]. Several types of sorbents have been studied for Hg0 removal from syngas, including activated carbon, noble metals, metal oxides, and metal sulfides [12–21]. Iron-based metal oxides adsorbents have attracted widespread attention due to their high adsorption activity, low cost, and easy preparation recovery. It is considered as a promising cost-effective technology for mercury removal from syngas. Iron-based sorbents, especially Fe2O3 or supported Fe2O3, are widely used for H2S removal due to their high adsorption capacity and low cost [23–25]. An activated coke supported Fe2O3 catalyst (Fe2O3/AC) was prepared and used for simultaneous removal of Hg0 and H2S in simulated coal-derived syngas. The influences of Fe2O3 loading and temperature and syngas components were studied, as well as the regeneration of Fe2O3/AC after Hg0 and H2S removal
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