One-pot synthesis of ceria and cerium phosphate (CeO2-CePO4) nanorod composites for selective catalytic reduction of NO with NH3: Active sites and reaction mechanism

Abstract

In this work, novel (CeO2)x-(CePO4)1−x (defined as CexP1−x) nanorod composites were prepared by a simple co-precipitation method, and the influence of CeO2 on the catalytic performance of CePO4 for selective catalytic reduction of NO by NH3 (NH3-SCR of NO) was investigated. The catalytic performance evaluation revealed that the CexP1−x catalysts, especially Ce0.2P0.8 exhibited a much better catalytic activity and H2O + SO2 resistance than CePO4. Structure characterizations via high-resolution transmission electron microscope (HRTEM) and Brunauer-Emmett-Teller (BET) revealed that the introduction of CeO2 had a little effect on the shape of CePO4 nanorods and it could promote the formation of new mesoporous then significantly enhance the surface area of catalyst. The analysis results of active sites suggested that phosphorus was the main adsorption site for NH3 and the redox sites were controlled by CeO2 on CexP1−x catalysts. Finally, reaction process study demonstrated that the NH3-SCR over CexP1−x was processed via Langmuir-Hinshelwood (L-H) mechanism. Combining the results of active sites and reaction mechanism analysis, it was drawn that the superior low temperature activity of CexP1−x could be attributed to its excellent redox properties, which promoted the oxidation of NO then facilitated the process of NH3-SCR via “fast SCR”.