Effect of fluoride doping for catalytic ozonation of low-temperature denitrification over cerium–titanium catalysts.

Nanostructure cerium–titanium catalysts including fluoride (F − ) doped ones were prepared by impregnation (Ce/TiO 2 and Ce/F–TiO 2 ) and co-precipitation (CeTi and CeTiF) method, and tested as ozonation catalysts for low-temperature NO X removal ranging from 40 to 180 °C. Interestingly, the doping of F − promotes the NO X removal for CeTi whereas inhibits the removal for Ce/TiO 2 . The NO X removal presents linear relationship with the concentration of hydroxyl radicals ( OH). The surface –OH linked to Ce atoms as well as the H 2 O adsorption over Ce atoms play the important role in the generation of ·OH radicals. The doping of F − into CeTi improves the activation of Ce–OH linkage bonds and the adsorption of H 2 O over Ce atoms, thus increasing the concentration of OH radicals and catalytic activities. Although the doping of F − into Ce/TiO 2 enhances the density of surface –OH, the ones linked to Ce atoms remain constant and the H 2 O adsorption over Ce atoms are declined, finally declining the catalytic activities. [ABSTRACT FROM AUTHOR]