Enhanced low-temperature SCR performance of metal Oxide/Cu-SSZ-13 composite catalysts: The role of oxygen species in metal oxide
Enhanced low-temperature SCR performance of metal Oxide/Cu-SSZ-13 composite catalysts: The role of oxygen species in metal oxide
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DOI：
10.1016/j.cej.2023.146407
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发表时间：
2023-10
影响因子：
15.1
通讯作者：
Yating Huang;Huawang Zhao;Xiaomin Wu;Zhiwei Huang;Huazhen Shen;Guohua Jing
中科院分区：
文献类型：
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作者：
Yating Huang;Huawang Zhao;Xiaomin Wu;Zhiwei Huang;Huazhen Shen;Guohua Jing
由金属氧化物和Cu-SSZ-13组分（OXZEO）组成的复合催化剂为解决当前提高SCR催化剂低温效率的挑战提供了一种有前途的方法。金属氧化物组分中存在的不同形式的氧影响硝酸盐的形成，硝酸盐在脱NOx途径中起关键作用，从而影响OXZEO中的整体SCR反应。尽管如此，金属氧化物中各种类型的氧与它们在OXZEO催化剂中的催化作用之间的关系仍然没有完全理解。为了阐明这种关系，比较和分析了分别与MnOx、CeOx和ZrOx组合的Cu-SSZ-13的活性。三种催化剂的低温路径（低于200 °C）主要归因于氧化物衍生的硝酸盐前体和沸石内结合到布朗斯特酸的NH3之间的相互作用。然而，MnOx/Cu-SSZ-13表现出更强的协同效应，在200 °C下实现比单独的Cu-SSZ-13高约50%的NOx转化率，这上级于其他两种复合催化剂。表征结果表明，具有表面氧空位的MnOx可以提供大量的化学吸附氧，从而产生更具反应活性的桥联硝酸盐，并促进MnOx/Cu-SSZ-13中硝酸盐与NH 4+的反应。相反，对于CeOx/Cu-SSZ-13和ZrOx/Cu-SSZ-13催化剂，金属氧化物的晶格氧促进活性较低的二齿和单齿硝酸盐的形成，导致较差的低温SCR性能。
A composite catalyst composed of metal oxide and Cu-SSZ-13 components (OXZEO) presents a promising approach to solve the current challenge of improving the low-temperature efficiency of SCR catalysts. The diverse forms of oxygen present within the metal oxide components impact the formation of nitrate, which plays a critical role in the deNOxpathway, thereby influencing the overall SCR reaction in OXZEO. Despite this, the relationship between the various types of oxygen in metal oxide and their catalytic role in OXZEO catalysts remain not fully understood. To clarify this relationship, the activities of Cu-SSZ-13 combined with MnOx, CeOx, and ZrOx, respectively, were compared and analyzed. The low-temperature pathway (below 200 °C) for the three catalysts is primarily ascribed to the interplay between oxide-derived nitrate precursors and NH3bound to Brønsted acids within the zeolite. However, MnOx/Cu-SSZ-13 demonstrated a stronger synergistic effect, achieving around 50 % higher NOxconversion than Cu-SSZ-13 alone at 200 °C, which was superior to the other two composite catalysts. Characterizations reveal that MnOxwith surface oxygen vacancies can supply a significant quantity of chemisorbed oxygen, thus producing more reactive bridged nitrates and bolstering the reaction between nitrate and NH4+in MnOx/Cu-SSZ-13. On the contrary, for CeOx/Cu-SSZ-13 and ZrOx/Cu-SSZ-13 catalysts, the lattice oxygen of the metal oxide encourages the formation of less active bidentate and monodentate nitrates, resulting in inferior low-temperature SCR performance.