Studies on the preparation of fly ash-derived Fe-SSZ-13 catalysts and their performance in the catalytic oxidation of NO by H2O2

Abstract

SSZ-13 zeolite was synthesized from fly ash using a combined alkali fusion hydrothermal method. The optimal synthesis parameters are as follows: NaOH/FA=1.4, SiO2/Al2O3=50, H2O/SiO2=1800, TMAda-OH/Al2O3=7, the amount of SSZ-13-seed=10%, and crystallization time and temperature were 160 °C and 40 h. Based on this, a series of fly ash-based Fe-SSZ-13 catalysts were prepared using three different methods and tested in catalytic oxidation with H2O2 for NO removal. The experiment results showed that the NO removal efficiency catalyzed by Fe-SSZ-13-SSIE, Fe-SSZ-13-LIE and Fe-SSZ-13-IM were 78%, 87% and 84%, respectively. ESR was used to detect hydroxyl radicals, UV-vis, XPS and H2-TPR were applied to test the composition, state and distribution of iron species, while NH3-TPD and Py-FTIR were performed to analyze the intensity and type of acidic sites, and finally to determine the relationship between catalyst structure, active species and catalytic performance in combination with NO removal experiments. The catalytic oxidation mechanism analysis revealed that the excellent catalytic performance can be attributed to the dual function of strong Brønsted acidity on the surface and isolated Fe3+ with high dispersion, which can rapidly decompose H2O2 into ·OH and efficiently achieve NO oxidation. In conclusion, the preparation of fly ash catalysts has great potential for achieving the dual function of waste utilization and pollutant removal.