活性炭催化氧化脱除单质汞的研究

摘要

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 180 min 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.%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180 min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.