Our previous study proved that the acid-pretreatment process could efficiently activate red mud (RM) for the selective catalytic reduction (SCR) of NO_x. However, in terms of the molding process, which is the key step determining whether it can be applied in large-scale industrial, the surface acidity and reducibility of catalyst always decreased dramatically, and part of surface area and pore structure were lost. In this study, we prepared monolithic honeycomb red mud (MHRM) catalysts with activated carbon (AC) as an accelerant and investigated the effect of AC on the MHRM. The results showed that the MHRM with 3 wt.% of AC (MHRM-AC3) exhibited the best SCR performance, and kept more than 80% NO_x conversion in the range of 325°C–400°C. Compared with the MHRM, MHRM-AC1, and HMRM-AC5, the MHRM-AC3 has more mesoporous and macroporous structures, which can provide more adsorption active sites. The AC significantly improved NH₃ adsorption and surface reducibility, which was mainly due to the increase of the surface acid sites (especially the Brönsted acid sites), the concentration of Fe(II), and the surface adsorbed oxygen. The presence of more Fe(II) enriched the surface oxygen vacancies, as well as the surface adsorbed oxygen, due to the charge imbalance and unsaturated chemical bond. And surface adsorbed oxygen exhibited more active than lattice oxygen owing to its higher mobility, which was conducive to NO_x reduction in the SCR reaction.

我们以前的研究证明，酸预处理过程能有效地激活为NO的选择性催化还原（SCR）赤泥（RM）_X。然而，就成型工艺而言，这是决定其能否应用于大规模工业的关键步骤，催化剂的表面酸度和还原性总是急剧下降，并且损失了部分表面积和孔结构。在这项研究中，我们用活性炭（AC）作为促进剂制备了整体式蜂窝红泥（MHRM）催化剂，并研究了AC对MHRM的影响。结果表明，含有3％（重量）AC的MHRM（MHRM-AC3）表现出最佳的SCR性能，并保留了80％以上的NO _x转换温度范围为325°C–400°C。与MHRM，MHRM-AC1和HMRM-AC5相比，MHRM-AC3具有更多的中孔和大孔结构，可以提供更多的吸附活性位点。AC显着改善了NH _3的吸附和表面还原性，这主要是由于表面酸位（特别是布朗斯台德酸位），Fe（II）浓度和表面吸附氧的增加所致。由于电荷不平衡和不饱和化学键的存在，更多的Fe（II）富集了表面氧空位以及表面吸附的氧。和表面吸附氧比晶格氧表现出多种活性，由于其更高的迁移率，这是有利于NO _X在SCR反应中还原。