Study on denitrification performance and mechanism of (Ce, La)PO4 under different calcination conditions

Abstract

The (Ce, La)PO₄ catalyst was synthesized utilizing the hydrothermal method. Calcination, a crucial step in catalyst preparation, was performed under four distinct conditions: muffle, microwave, N₂, and O₂ atmospheres. This study examined the impact of these calcination conditions on the Selective Catalytic Reduction (SCR) activity, as well as the physical and chemical properties of the (Ce, La)PO₄ catalysts. The microwave calcination condition was found to decrease the crystallinity of the samples and enhance the dispersion of active material on the catalyst surface compared to the other methods. Based on the results of Brunauer–Emmett–Teller (BET) and NH₃-Temperature Programmed Desorption (NH₃-TPD) analyses, microwave calcination not only increased the specific surface area of the samples but also revealed more acidic sites on the catalyst surface, thereby improving the adsorption–desorption performance for NH₃. Furthermore, microwave calcination enhanced the redox performance of the catalyst and consequently improved the NO_x conversion efficiency. In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis suggested that the Selective Catalytic Reduction on the (Ce, La)PO₄ catalyst surface followed both the Langmuir–Hinshelwood and Eley–Rideal mechanisms. A comparative analysis of the effects of different calcination conditions on catalyst performance revealed that microwave calcination was the most effective in enhancing catalyst performance. This finding provides valuable guidance for catalyst synthesis.