Construction Of Cu-Ce Catalyst And Its Catalytic Performance For Ammonia Oxidation

Ammonia is a typical harmful gas that is colorless and has a strong pungent,pungent odor.It not only threatens ecological environment,but also endangers human health.Therefore,ammonia control and elimination has important environmental and social significance.Currently,selective catalytic oxidation of ammonia?NH₃-SCO?is a potential and effective treatment technology.However,the interaction mechanism between Cu-Ce catalysts is unclear and the NH₃ oxidation activity of the catalysts is rather poor at the low temperature.To solve these problems,nanosized Cu-Ce catalysts with different morphologies have been synthesized and the physical and chemical properties of catalysts were analyzed by various characterization methods.The interaction mechanism of Cu-Ce catalysts was explored and then the morphology-structure-activity relationship of the catalysts were preliminary discussed.The distribution and dislocation of Cu on the surface of the carrier are regulated by changing the compound mode of Cu,so that it has good activity and stability.First,the Cu-Ce catalysts with different morphologies are used as NH₃ oxidation catalysts in order to investigate how the morphology of support affect the synergy of Cu and Ce and the NH₃ oxidation activity.Analysis reveals that the nanorod CeO₂ preferentially exposes{110}and{100}crystal plane,which is more favorable for the dispersion of Cu,and Cu²⁺can incorporate the surface or subsurface of ceria.The surface of Cu/Ce-NR catalyst has more oxygen vacancies and surface adsorptive oxygen species and lower temperature H₂ reduction performance than the Cu/Ce-NC catalyst.Particularly,the Cu/Ce-NR catalyst showed the best NH₃ conversion and the lowest complete conversion temperature at 240^oC,and the N₂selectivity was above 93%.Second,the effect of the compound mode of Cu on the dispersion of Cu,structural property and redox property as well as catalytic performance of Cu-Ce catalysts for NH₃-SCO reaction were investigated.Analysis reveals that Cu-Ce catalysts prepared by sol-gel method exhibit more good disperse of copper,Cu-O-Ce structure species and lower temperature H₂ reduction performance.The Cu-Ce?SOL?catalysts possess the best activity of NH₃-SCO reaction with complete NH₃ conversion at 230^oC and over 96%N₂ selectivity.After the ten cycle's experiments of the catalyst,the activity unchanged.The stability experiment was performed for36 hours,the conversion was still above 99%,and the N₂ selectivity remained at about 96%.The NH₃ concentration is further increased to 1500 ppm,it also had a excellent stability,reaching 100%at 230^oC.