CrOx Anchored on the Black-TiO2 Surface via Organic Carboxylic Acid Ligand and Its Catalysis in Oxidation of NO

CrO x /black-TiO 2 catalysts were prepared by ligand-assisted (citric acid, oxalic acid and ethylenediaminetetraacetic acid) impregnation method. These catalysts were characterized in detail by means of X-ray diffraction, Raman, BET, X-ray photoelectron spectroscopy, H 2 and O 2 (NO) temperature programmed reduction or desorption and in-suit DFTIR spectra. The results indicated that ligands assistance was beneficial for CrO x interacted with oxygen vacancies and O–Ti–O structures. Among all the catalysts, CrO x /black-TiO 2 /CA (modified by citric acid) revealed excellent catalytic activity and stability for NO oxidation in the temperature range of 200–450 °C. The characterization results exhibited that the interaction existed between CrO x and oxygen vacancies resulting in more Cr 6+ . Moreover, the strong interaction between CrO x and O–Ti–O was attributed to the modification of carboxylic acid, which increased the content of Cr 3+ and chemical adsorption oxygen. High content of chemical adsorption oxygen promoted the adsorption ability of O 2 , and Cr 6+ enhanced the adsorption capacity of NO. Hence, chemical adsorption oxygen and Cr 6+ synergistically promoted the NO oxidation. Graphic Abstract