Preparation and characterization of Ce0.3Ti0.7O2 and supported CuO catalysts for NO plus CO reaction

The CexTi1-xO2 mixed oxides at different mole ratios (x = 0.1 - 1.0) were prepared by co-precipitation of TiCl4 and Ce(NO3)(3). The structural and reductive properties of the CexTi(1-x)O(2) were affected by calcination temperature. At x = 0.1 - 0.3, CeTi2O6 phase was formed and mainly as amorphous after calcination at 650 degreesC. At x = 0.3, only CeTi2O6 was formed after calcination at 750 degreesC and CeTi2O6 crystallized completely after calcination at 800 degreesC. TPR analyses showed that the amount of H-2 consumption by CexTi1-xO2 (650 degreesC) (except x = 0.1) was greater than that by single CeO2, and the valence of CeO2 was the lowest (+ 3.18) at x = 0.3. CuO/Ce0.3Ti0.7O2 was prepared by the impregnation method and catalytic properties were examined by means of a GC micro-reactor NO+ CO reaction system, BET, TPR, XRD, XPS and NO-TPD. It was found that CuO/Ce0.3Ti0.7O2 calcined at 650 degreesC had the highest activity in NO+ CO reaction with 100% NO conversion at reaction temperature of 300 degreesC, and at 650 degreesC Ce0.3Ti0.7O2 just began to crystallize. The catalytic activities were largely affected by the pre-treatment conditions. At low reduction temperature (100 degreesC), CuO species was difficult to reduce. When high degree of reductions took place, both CuO species and Ce0.3Ti0.7O2 reduced and thus a part of CuO species on the support surface would be covered. The XPS and NO-TPD analyses showed that CuO/Ce0.3Ti0.7O2 had four NO absorption centers (Cu+, Cu2+(I), Cu2+(II) and Ce3+). The CuO species involving in NO+ CO reaction included Cu2+(I) and Cu+, and CeO2 species (Ce3+ and Ce4+).