天然矿物MgO被认为是负载MnOx脱除燃煤烟气中Hg0的优良载体，然而其比表面积限制了Mn物种的利用效率，对Mn物种的用量需求较高。为提高载体在脱除烟气中Hg0反应过程中对Mn活性物种的利用率，采用Al2O3部分替换MgO，制备了MgO-Al2O3复合氧化物负载的MnOx吸附剂。利用Al2O3较大的比表面积以及表面较高的化学吸附氧（Oad）占比，提升了Mn对Hg0的吸附与氧化能力，获得了Hg0脱除效率更高的吸附剂。结果表明，仅负载5%的Mn物种时，在MgO载体中添加30%的Al2O3可使吸附剂在150 ℃、N2+10% O2气氛中提升Hg0脱除效率27.7%。通过H2-TPR及XPS揭示吸附剂对Hg0的脱除机理，H2-TPR表明添加Al2O3会与MgO发生交互反应形成更稳定的载体物种，XPS表明吸附剂表面Mn4+物种占比对Hg0脱除活性有重要影响，添加30%的Al2O3时吸附剂表面Mn4+物种占比最高，因此Hg0脱除活性最高。针对MgO载体上Mn活性组分受限的缺点，采用添加Al2O3的方法提升了载体对于活性物种的利用率，对天然矿物载体在Hg0脱除领域的应用具有借鉴意义。

Natural mineral (MgO) is considered to be an excellent support for loading MnOx to remove Hg0 from coal-fired flue gas. However, the restricted specific surface area of MgO limits its utilization efficiency for Mn species, and the amount of Mn species is always quite high. In order to improve the utilization of Mn active species by MgO support in the reaction of removing Hg0 from flue gas, MnOx sorbents supported by MgO-Al2O3 composite oxides were synthesized by partially replacing MgO with Al2O3. With the aid of the large specific surface area and the high proportion of chemically adsorbed oxygen (Oad) on the surface of Al2O3, the adsorption and oxidation capacity of Mn species for Hg0 was improved, and a sorbent with higher Hg0 removal efficiency was obtained. The activity test results show that when only 5% Mn species is loaded, adding 30% Al2O3 into the support can improve the Hg0 removal efficiency by 27.7% compared with the sorbent without Al2O3 in the N2+10% O2 atmosphere at 150 ℃. The mechanism of the sorbent for Hg0 removal was revealed by H2-TPR and XPS. H2-TPR shows that Al2O3 will interact with MgO to form a more stable carrier species after the addition of Al2O3. XPS shows that the proportion of Mn4+ species on the sorbent surface has an important influence on the Hg0 removal activity. When adding 30% Al2O3, the proportion of Mn4+ species on the sorbent surface is the highest, so the Hg0 removal activity is the highest. In view of the limitation of Mn active components by MgO support, the method of adding Al2O3 can improve the utilization of the active species, which has a guiding significance for the application of natural mineral support in the field of Hg0 removal.

0 引言

1 试验

   1.1 吸附剂制备

   1.2 吸附剂表征

   1.3 活性测试

2 结果与讨论

   2.1 吸附剂基础特性表征

   2.2 吸附剂Hg0脱除活性测试

   2.3 Hg0脱除机理

3 结论