Abstract：
In response to the stricter EU VII emission standards and the \"150 ℃ challenge\", selective catalytic reduction by ammonia (NH3-SCR) catalysts for motor vehicles are required to achieve high NO conversion below 200 °C. Compounding metal oxides with zeolites is an important strategy to design the low-temperature SCR catalysts. Here, we original prepared Cu-SSZ-13 @ MnGdOx (Cu-Z @ MGO), which achieved over 90% NO conversion and 95% N2 selectivity at 150 ℃. It has been demonstrated that a uniform mesoporous loaded layer of MGO grows on Cu-Z, and a recrystallization zone appears at the MGO-Cu-Z interface. We discover that the excellent low-temperature SCR activity derives from the strong metal oxide-zeolite interaction (SMZI) effects. The SMZI effects cause the anchor and high dispersion of MGO on the surface of Cu-Z. Driven by the SMZI effects, the Mn3+/Mn4+ redox cycle ensures the low and medium temperature-SCR activity and the Cu2+/Cu+ redox cycle guarantees the medium and high temperature-SCR activity. The introduction of MGO improves the reaction activity of -NH2 species adsorbed at Mn sites at 150 ℃, achieving a cycle of reduction and oxidation reactions at low temperatures. This strategy of inducing SMZI effects of metal oxides and zeolites paves a way for development of high-performance catalysts.
摘要：
为了应对更严格的欧盟VII排放标准和“150℃挑战”，用于机动车辆的氨选择性催化还原(NH3-SCR)催化剂需要实现低于200°C的高NO转化率。将金属氧化物与沸石混合是设计低温SCR催化剂的重要策略。这里,我们原始制备的Cu-SSZ-13@MnGdOx（Cu-Z@MGO），在150℃下实现了90%以上的NO转化率和95%的N2选择性。已经证明，MGO的均匀介孔负载层在Cu-Z上生长，在MGO-Cu-Z界面出现再结晶区。我们发现优异的低温SCR活性来源于强的金属氧化物-沸石相互作用(SMZI)效应。SMZI效应导致MGO在Cu-Z表面的锚定和高分散。在SMZI效应的驱动下，Mn3+/Mn4+氧化还原循环确保了低温和中温SCR活性，Cu2+/Cu+氧化还原循环确保了中温和高温SCR活性。MGO的引入提高了-NH2物种在150℃下吸附在Mn位点的反应活性，在低温下实现还原和氧化反应的循环。这种诱导金属氧化物和沸石的SMZI效应的策略为开发高性能催化剂铺平了道路。
