SURFACE CHARACTERIZATION OF ZIRCONIUM-OXIDE .2. THE INTERACTION WITH CARBON-DIOXIDE AT AMBIENT-TEMPERATURE

FTIR spectroscopy has been used to study the room temperature interaction between CO2 and a pure monoclinic ZrO2 preparation, activated at various temperatures. Three types of linear CO2 species were observed, σ-coordinated at Lewis acidic centres. Two of them correspond to the Lewis sites produced upon surface dehydroxylation and which also σ-coordinate CO, though modified by the simultaneous presence at the surface of carbonate-like species, whereas the third type of sites correspond to the surface removal of undissociated coordinated water. Various types of carbonate-like species were also observed, whose complex nature depends on the dehydration and on the sintering stage of Zr02. Most peculiar are (bidentate) bicarbonates and bidentate carbonates, which can convert into one another by varying the surface hydration degree. In addition, monodentate carbonates form on high surface area (polydispersed) samples, whereas they tend to disappear on partly sintered and more ordered materials. © 1990.