Effects of cerium and tungsten addition on acid-base properties of spindle-like ?-Fe2O3 in low-temperature SCR of NOx with NH3

Low-temperature selective catalytic reduction (SCR) is important for the elimination of NOx from sta-tionary sources. In the present study, the loading of Ce and W on a-Fe2O3 was achieved through the integration of single-mode microwave and incipient wetness impregnation (IWI) methods. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images reveal that the structure of a-Fe2O3 is spindle-like, and the structure remains unchanged after the introduction of Ce and/or W. The results of NH3-SCR investigation demonstrate that NOx conversion over Ce-W/a-Fe2O3 is more than 85% at 300 degrees C, which is much higher than that over Ce/a-Fe2O3 and a-Fe2O3. Our studies illustrate that the addition of Ce can significantly increase the amount of surface oxygen vacancies as well as sites of moderate basicity. On the other hand, the addition of W can obviously decrease the amount of basic sites and increase the number of Bronsted acid sites. The synergistic effect of Ce and W addition on balancing acidity/basicity properties accounts for the high activity of Ce20W10/a-Fe2O3 for NOx removal at low temperatures. The study provides insight into the relationship between acidity/basicity properties and catalytic performance of Ce-W/a-Fe2O3 catalysts, which is beneficial to the design of high-performance NH3-SCR catalyst for NOx removal at low temperatures. (c) 2022 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.