Qi-lin Chen

Deactivation of Mn/TiO2 catalyst for NH3-SCR reaction: effect of phosphorous

The deactivation mechanism of phosphorous on a Mn/TiO2 catalyst for selective catalytic reduction of NO with NH3 was investigated in this study. It was found that the NH3-SCR reaction over the Mn/TiO2 catalyst obeyed the Langmuir–Hinshelwood mechanism. From the characterization results, it could be found the addition of phosphorous on the Mn/TiO2 catalyst would decrease its reducibility and inhibit the adsorption of chemisorbed oxygen and NOx species on its surface. As a result, the P-doped Mn/TiO2 catalyst was deactivated.

A CeFeOx catalyst for catalytic oxidation of NO to NO2

Abstract Catalytic oxidation of NO into NO 2 is a promising method for NO x emission control. The aim of this study was to develop an economic and environmental-friendly catalyst for NO catalytic oxidation. Herein a CeFeO x complex oxide catalyst for catalytic oxidation of NO was prepared by coprecipitation method. After that the catalytic performance of this catalyst was measured on a fixed-bed reactor. It was found that the intrinsic activity of CeFeO x was higher than that of CeO x and FeO x . The characterization techniques of Brumauer-Emmett-Teller (BET), X-ray diffraction (XRD), temperature programmed reduction with H 2 (H 2 -TPR), temperature programmed desorption with NO+O 2 (NO+O 2 -TPD) and X-ray photoelectron spectroscopy (XPS) were performed to investigate the surface area, crystal structure, redox property and NO x adsorption behavior of the catalyst samples. From the characterization results, it was concluded that the low crystallinity of CeFeO x promoted the dispersion of active species, as a result, enhancing the redox ability and NO adsorption capacity of CeFeO x catalyst, which is favorable to NO catalytic oxidation. Furthermore, the presence of much chemisorbed oxygen on CeFeO x catalyst also made a great contribution to its good catalytic performance.

The enhanced performance of a CeSiOx support on a Mn/CeSiOx catalyst for selective catalytic reduction of NOx with NH3

A series of Mn/CeSiOx catalysts were prepared by the wet impregnation method and used for selective catalytic reduction of NO with NH3. As can be seen from the experimental results, the Mn/CeSiOx catalyst with a Ce/Si molar ratio of 2/1 showed excellent low-temperature SCR activity, high N2 selectivity and excellent SO2 and H2O tolerance. The relationship between the CeSiOx support and the SCR performance of Mn/CeSiOx (2 : 1) catalyst was investigated based on the characterization results of N2 adsorption, XRD, XPS, H2-TPR, NH3-TPD and in situ DRIFT. The strong interaction between Ce and Si resulted in the good dispersion of Mn species on the support; correspondingly, the redox ability and NH3 adsorption capacity were greatly enhanced. The results of in situ DRIFT study revealed that the NH3-SCR reactions over Mn/CeO2 and Mn/CeSiOx (2 : 1) mainly obeyed both the E–R mechanism and the L–H mechanism. Furthermore, the formation of more Mn4+ and chemisorbed oxygen greatly facilitates the oxidation of NO to NO2, as a result, promoting the low-temperature SCR performance of Mn/CeSiOx (2 : 1).