Cite this article: Liu, H., Zhang, Z., Li, Q., Chen, T., Zhang, C., Chen, D., Zhu, C. and Jiang, Y. (2017). Novel Method for Preparing Controllable Nanoporous α-Fe2O3 and its Reactivity to SCR De-NOx.
Aerosol Air Qual. Res.
17: 1898-1908. https://doi.org/10.4209/aaqr.2017.05.0188
Controllable nano-porous α-Fe2O3 was prepared.
α-Fe2O3 prepared between 400°C and 600°C exhibited excellent SCR activity.
The well-defined α-Fe2O3 and corresponding low surface area reduced the SCR activity.
E-R mechanism played a more important role than L-R mechanism for α-Fe2O3 catalyst.
Controllable nanoporous hematite (CNH, α-Fe2O3) was prepared by thermal treatment of α-FeOOH at different temperatures, and the SCR activity of the prepared α-Fe2O3 was evaluated. XRD (X-ray diffraction), HRTEM (high-resolution transmission electron microscopy), N2 adsorption-desorption, XPS (X-ray photoelectron spectroscopy), and NH3-TPD (NH3-temperature programmed desorption) were utilized to characterize the catalysts. The results indicated that after thermal treatment at less than 600°C, the α-Fe2O3 catalysts exhibited excellent NO conversion that was higher than 80% in a temperature range from 300 to 400°C. CNH400 with a relatively large surface area of 47.24 m2 g–1 and many surface hydroxyl groups did not exhibit a substantially improved SCR activity even though it exhibited the best SCR activity. Therefore, the L-H mechanism was not the main reaction route for SCR of NO by α-Fe2O3. The increasing crystallization of α-Fe2O3 decreased the SCR activity, indicating that a decrease in surface oxygen defects was important for the SCR of NO and fitting the E-R mechanism. The NH3-TPD and XPS (O1s) results confirmed this hypothesis. This study provides an approach for the design and preparation of a controllable nanoporous α-Fe2O3 catalyst for SCR of NO by NH3.