Catalytic Decomposition of N2O over Co-Ti Oxide Catalysts: Interaction between Co and Ti Oxide

A series of CoxTi catalysts with different Co/Ti molar ratios (x=0.2, 0.4, 0.6, and 0.8) were prepared by the sol-gel method and used for N2O decomposition. The catalysts were characterized by XRD, X-ray photoelectron spectroscopy (XPS), TEM, temperature-programmed reduction with H-2, temperature-programmed desorption of O-2, diffuse reflectance UV/Vis, Raman spectra, and N-2 adsorption-desorption measurements. The results indicate that the CoxTi catalysts possess high Brunauer-Emmett-Teller (BET) surface area, more surface Co3+, and even better structural stability than Co3O4 as a result of the strong interactions between Co and Ti oxide. Deactivation occurred over time for the Co3O4 catalyst, however, Co0.6Ti maintains nearly 100% N2O conversion for at least 30h. Moreover, the Co0.6Ti catalyst showed much stronger resistance against 1.5vol.% O-2, 2.4vol.% H2O, or 1.6vol.% NO in the feed compared with the Co3O4 catalyst. The excellent activity of the Co0.6Ti catalyst can be attributed to the higher amount of surface Co3+ derived from the interaction of the Co and Ti oxide in the CoxTi catalysts.