Ammonia-steam treated FeZSM-5 for direct N2O decomposition

Abstract 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 N2, 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 °C for the best ammonia steam activated sample, while it is 575 °C for the conventional steam activated sample under the same reaction conditions. Various techniques, such as X-ray diffraction (XRD), scanning electronic microscope (SEM), N2 adsorption/desorption, ultraviolet–visible spectroscopy (UV–vis) 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 N2O–CO titration experiments.