Phosphorus poisoning and hydrothermal aging deactivation mechanism of vanadium-based nitrogen oxide purification catalysts

This study delves into the impact of phosphorus poisoning and hydrothermal aging on the selective catalytic reduction of nitrogen oxides by vanadium-based catalysts during mobile source exhaust purification. The findings reveal that phosphorus poisoning is more likely to reduce the nitrogen oxide purification efficiency of vanadium-based catalysts compared to hydrothermal aging, particularly leading to a significant decline in selective catalytic reduction activity in the low-temperature range. Utilizing various characterization techniques such as powder diffraction pattern, Raman spectroscopy, temperature-programmed adsorption and reduction process, photoelectron spectroscopy, and in-situ diffuse reflectance Fourier transform infrared spectroscopy, the study uncovers the deactivation mechanisms of phosphorus poisoning and hydrothermal aging in vanadium-based nitrogen oxide purification catalysts during mobile source exhaust treatment. The research indicates that phosphorus poisoning primarily causes catalyst deactivation by inducing the formation of phosphate structures on the catalyst surface, altering the redox capabilities of active vanadium species, and inhibiting the generation of key reaction intermediates. The hydrothermal aging process further exacerbates the effects of phosphorus poisoning on the crystal structure, active species morphology, and redox properties of the catalyst, leading to a significant reduction in nitrogen oxide purification efficiency. The systematic understanding of the deactivation effects of phosphorus poisoning and hydrothermal aging on vanadium-based catalysts provided by this study offers crucial theoretical foundations and scientific support for the development of efficient nitrogen oxide purification catalysts that resist phosphorus poisoning and hydrothermal aging.