The NiSO4/CeO2-ZrO2 catalysts containing different nickel sulfate and CeO2 contents were prepared by the impregnation method, where support, CeO2-ZrO2 was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride a...
The NiSO4/CeO2-ZrO2 catalysts containing different nickel sulfate and CeO2 contents were prepared by the impregnation method, where support, CeO2-ZrO2 was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and cerium nitrate solution followed by adding an aqueous ammonia solution. No diffraction line of nickel sulfate was observed up to 20 wt %, indicating good dispersion of nickel sulfate on the surface of CeO2-ZrO2. The addition of nickel sulfate (or CeO2) to ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperatures because of the interaction between nickel sulfate (or CeO2) and ZrO2. A catalyst (10-NiSO4/1-CeO2-ZrO2) containing 10 wt % NiSO4 and 1 mole % CeO2, and calcined at 600 C exhibited a maximum catalytic activity for ethylene dimerization. The catalytic activities were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The role of CeO2 was to form a thermally stable solid solution with zirconia and consequently to give high surface area, thermal stability and acidity of the sample.