Tian You, Han Zhitao, Zeng Qingliang, Zhao Hongzhe, Li Yeshan, Ma Dong
Marine Engineering College, Dalian Maritime University, Dalian 116026, China.
Marine Engineering College, Dalian Maritime University, Dalian 116026, China.
J Hazard Mater. 2025 Mar 15;486:137108. doi: 10.1016/j.jhazmat.2025.137108. Epub 2025 Jan 2.
Ammonia selective catalytic oxidation (NH-SCO) is an effective method for NH removal. However, it is still a great challenge to develop catalysts with a wide operating temperature window, high catalytic activity and N selectivity, particularly for the removal of high-concentration NH from NH-fueled engine exhaust gas. Herein, a small amount of Ru (0.5 wt%) together with W were used to co-modify CeZrO through impregnation method to synthesize a novel NH-SCO catalyst. The as-prepared Ru-W/CeZrO catalyst could achieve a complete NH conversion at 300 °C, and a superior N selectivity, which exceeded 95.7 % over a wide temperature range of 225-400 °C. The physicochemical properties of the prepared catalysts were compared using various characterization techniques to reveal the possible roles of Ru and W species in NH-SCO reaction. XPS results showed that the introduction of Ru species was in favor of forming abundant surface adsorbed oxygen species on the surface of Ru-W/CeZrO catalyst, significantly enhancing the low-temperature activity. Besides, the co-existing W species could suppress the excessive oxidation of NH on catalyst surface, which was crucial for improving N selectivity. In-situ DRIFTS results suggested that Ru-W/CeZrO catalyst followed both the internal selective catalytic reduction (i-SCR) and amide (-NH) mechanisms during NH-SCO reaction. More importantly, the NH species adsorbed on Ru-W/CeZrO catalyst surface reacted more rapidly than that of W/CeZrO catalyst, and were mainly converted to N rather than NO or NO under the synergy of Ru and W species.
氨选择性催化氧化（NH-SCO）是一种去除氨的有效方法。然而，开发具有宽操作温度窗口、高催化活性和N选择性的催化剂仍然是一个巨大的挑战，特别是对于从以氨为燃料的发动机废气中去除高浓度氨而言。在此，通过浸渍法使用少量Ru（0.5 wt%）与W共同改性CeZrO，以合成一种新型NH-SCO催化剂。所制备的Ru-W/CeZrO催化剂在300°C时可实现氨的完全转化，并且具有优异的N选择性，在225-400°C的宽温度范围内超过95.7%。使用各种表征技术比较了所制备催化剂的物理化学性质，以揭示Ru和W物种在NH-SCO反应中的可能作用。XPS结果表明，Ru物种的引入有利于在Ru-W/CeZrO催化剂表面形成丰富的表面吸附氧物种，显著提高了低温活性。此外，共存的W物种可以抑制催化剂表面氨的过度氧化，这对于提高N选择性至关重要。原位DRIFTS结果表明，Ru-W/CeZrO催化剂在NH-SCO反应过程中遵循内部选择性催化还原（i-SCR）和酰胺（-NH）机制。更重要的是，吸附在Ru-W/CeZrO催化剂表面的氨物种比W/CeZrO催化剂的反应更快，并且在Ru和W物种的协同作用下主要转化为N而不是NO或NO。
