Catalytic Mechanism of NaY Zeolite Supported FeSO4 Catalyst for Selective Catalytic Reduction of NOx

Abstract

The experimental results suggested that FeSO4-NaY and FeSO4-ZSM-5 prepared by impregnation method performed well in NOx removal. The NOx removal rates of the prepared catalyst were 20–35% higher than those of pure FeSO4, The effective temperature window was largely expanded with the best performance temperature shifted from 440 to 340°C. SO2 and H2O in flue gas had no obvious effect on catalyst performance. Mossbauer spectrometry, XPS and in-situ infrared spectra analysis had been employed to investigate the catalytic mechanism of catalysts. It had been found that FeSO4, Fe(OH)SO4 and Fe2O(SO4) were the major components existing in the prepared catalyst, with their portions related to carrier type and preparing condition. FeSO4 combined tighter with carriers after de-NOx reaction. Fe2O3 and the chemical bond between Fe and Al had been found. Fe(OH)SO4 was better in terms of NOx removal than that of Fe2O(SO4). NH3 absorbed on FeSO4-NaY catalyst generated the spectra of NH 4 + and NH3, suggesting the Eley-Rideal mechanism. FeSO4-ZSM-5 absorbed both NH3 and NO and the carrier (ZSM-5) itself demonstrated some catalytic effect, indicating a different reaction mechanism. \( {\text{SO}}_4^{{2 - }} \) from FeSO4 and hydroxyl from carrier jointly enhanced the adsorption of reaction gas. Fe provided the active sites for the reaction between NH3 and NO.