Influence of Interaction Components on the NOx Adsorption Properties of Cu–Ba–Ce Composite Catalysts

For further investigating the role of components in copper-cerium-barium composite oxide catalysts, a series of noble metal-free catalysts with different barium contents were synthesized by citric acid method. The prepared catalysts were characterized by X-ray diffraction, Brunauer-Emmett- Teller method, scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy. Catalysts were evaluated by NO oxidation, NOx adsorption, and NOx temperature-programmed desorption. The results showed that barium content significantly affected the catalysts' properties. With barium addition, interactions among components considerably changed; hence, the microstructure and performance of catalysts were distinctly different. In general, the interactions of barium-copper and barium-cerium were not conducive to catalyst adsorption. Adsorption performance derived from barium carbonate was superior to those of the other two components.