Study On The Catalytic Properties And Active Sites Of Iron Containing AlPO-5 Catalysts For N₂O Catalytic Reduction With Methane

N₂O not only has strong greenhouse effect which is about 300 times greater than CO₂ but also can lead to stratospheric ozone layer depletion, therefore, it is an important pollutant in the atmosphere. The concentration of N₂O in the atmosphere has been increasing year by year since the Industrial Revolution. So effectively removal of N₂O becomes one of the main tasks of environmental protection and sustainable development. Catalytic reduction of N₂O with methane attracted the attention of scholars from home and abroad has been considered a promising N₂O removal method, because methane which is present in most combustion exhausts could also lead to greenhouse effect.At present, the catalysts for N₂O catalytic reduction with methane have high cost and poor hydrothermal stability. As molecular sieve has a wide range of applications in many areas, launching the relevant research of zeolite synthesis and application is of great significance. Because of its unique pore structure and diverse functions, the heteroatoms substituted aluminophosphate Sieves (M-AlPO-5) is a good catalyst for many reactions. The catalytic performance and active site of FeAlPO-5 catalysts for catalytic reduction of N₂O with methane are investigated; on this basis, the modification of FeAlPO-5 catalyst has been studied. The main research contents are as follows:(1) FeAlPO-5 catalysts with different Fe content were prepared by hydrothermal method and evaluated in catalytic reduction of N₂O with methane exhibiting good low-temperature activity. A series of Characterizations had been carried out to explain the evaluation results and find the relationship between catalyst active sites and catalytic properties. The obtained results as follows: The hydrothermally prepared FeAlPO-5 catalysts had a typical framework structure of AlPO-5 zeolite; the Fe content had a great impact on the distribution of Fe species.(2) The catalysts prepared by different methods exhibit different performances to this reaction. The FeAlPO-5 catalyst synthesized by hydrothermal method showed a higher catalytic activity and could maintain a good stability under the conditions of excess O₂ and steaming. XRD, FT-IR, BET, UV-Vis, and H₂-TPR characterization results indicated that the different distribution and coordination forms can be the main reasons for the catalysts prepared with different methods have the different catalytic activity and stability. (3) In order to further improve the low-temperature activity, we loaded a small amount of precious metal components which can promote low-temperature activity by impregnation method in FeAlPO-5 catalyst. The research results proved that a small amount of Pd loading can be markedly improved catalytic activity.