活性炭催化氧化脱除单质汞的研究

模拟煤气的气氛,在硫化氢（H₂S）和氧气（O₂）存在条件下,对活性炭催化氧化吸附单质汞（Hg⁰）的性能进行了研究。结果表明，H₂S和O₂存在条件下,活性炭对Hg⁰的吸附能力明显提高。在180min内,H₂S和O₂共存气氛下,脱汞效率约为78%;只有H₂S存在下,脱汞效率约为69%;没有H₂S和O₂气氛下活性炭脱汞效率快速下降为28%。随着吸附温度的升高,入口汞浓度的提高和吸附剂粒径的增大,活性炭的脱汞效率会随着下降。通过XRD表征表明,Hg⁰的吸附反应机理是Hg⁰在活性炭催化氧化下与H₂S形成硫化汞（HgS）,从而实现了Hg⁰的稳定化脱除。

Stabilized oxidation and adsorption of elemental mercury by activated carbon

The catalytic oxidation and adsorption capabilities for elemental mercury (Hg⁰) on activated carbon (AC) were evaluated in a simulated coal-derived gas containing hydrogen sulfide (H₂S) and oxygen (O₂). The Hg⁰ removal efficiency is close to 78% in the atmosphere containing H₂S and O₂ in 180min at 160℃, whereas the retention of mercury without H₂S and O₂ sharply decreases from 69% to 28% in the same duration. Higher adsorption temperature, larger size of sorbent and higher Hg⁰ concentration may deteriorate to the absorption capability. XRD was used to characterize properties of the sorbents. It shows that mercury sulfide (HgS) is formed over the AC after the adsorption. It is suggested that the oxidation reaction of Hg⁰ with H₂S and O₂ may contribute to the efficient capture of Hg⁰ over AC sorbent. HgS formation is beneficial to improve the Hg⁰ removal efficiency and the adsorption capacity of the AC sorbent. Furthermore, it has the advantage to reduce the secondary pollution due to HgS being inert and nontoxic to the environment.