Ammonia-steam treated FeZSM-5 for direct N2O decomposition

Steaming posttreatment has been reported to be an efficient way to activate FeZSM-5 for the direct N2O decomposition. Herein, ammonia steams with different partial pressures, which originate from the evaporation of ammonia aqueous solution and dilution by N-2, have been adopted to treat FeZSM-5 zeolites at high temperatures for different time. The direct N2O decomposition on the FeZSM-5 catalysts indicates that the ammonia steam treatment could greatly improve the activity. The temperature required for complete N2O decomposition is decreased to 525 degrees C for the best ammonia steam activated sample, while it is 575 degrees C for the conventional steam activated sample under the same reaction conditions. Various techniques, such as X-ray diffraction (XRD), scanning electronic microscope (SEM), N-2 adsorption/desorption, ultravioletvisible spectroscopy (UVvis) and Fourier transform infrared spectroscopy (FTIR) etc., have been used to characterize the catalysts. Results indicate that ammonia steam is beneficial to keep a higher crystallinity than that of steam, and produces more Fe active species confirmed by the N2OCO titration experiments.