Work

Sequential sulfidation engineering in Ce-Zr catalysts: Acid site evolution steering reaction pathway optimization for NH3-SCR systems

Year: 2025

Type: article

Abstract: In this study, a series of Ce-Zr catalysts were synthesized via conventional coprecipitation method, and the mechanistic impacts of sulfation sequences on NH 3 -SCR performance were systematically investigated. The experimental results demonstrated that the Ce-Zr-S catalyst exhibited the optimal NO conversion efficiency (approximately 90 %) at 275 °C. XRD characterization revealed that the synergistic sulfurization strategy effectively facilitated the formation of Ce-Zr solid solutions, which partially suppressed the deactivation of active sites. EPR spectroscopy analysis indicated that the Ce-Zr-S catalyst possessed higher oxygen vacancy concentration compared to other counterparts, which enhanced the Ce 4 + /Ce 3+ redox cycling and subsequently improved oxygen storage capacity (OSC) as well as redox activity. Pyridine-IR, NH 3 -TPD and in situ DRIFTS investigations confirmed that the Brønsted acid site density of Ce-Zr-S was significantly increased. These acid sites functioned as active centers for direct adsorption of NH 4 + species. Importantly, the generated NH 2 NO intermediate was found to promote chemical adsorption/activation of NO molecules, thereby reducing the energy barrier of subsequent reduction steps and ultimately boosting the low-temperature catalytic performance of Ce-Zr-S catalyst.

Source: Journal of Alloys and Compounds

DOI: 10.1016/j.jallcom.2025.182795