| 초록 |
A series of catalysts, NiSO4/TiO2-ZrO2, for ethylene dimerization was prepared by the impregnation method using an aqueous solution of nickel sulfate. Calcination at 300-600 ℃ of coprecipitated Ti(OH)4-Zr(OH)4 resulted in the formation of an amorphous phase and further heating at 700 ℃ and above resulted in the formation of crystalline ZrTiO4 compound. The addition of nickel sulfate to TiO2-ZrO2 shifted the phase transition of TiZrO4 from amorphous to orthorhombic to higher temperature because of the interaction between nickel sulfate and TiZrO4, and the specific surface area and acid amount of NiSO4/TiO2-ZrO2 increased in proportion to the nickel sulfate content up to 10-20 wt% of NiSO4. Nickel sulfate supported on TiO2-ZrO2 was found to be very active even at room temperature, giving a maximum in both activity and acidity when catalyst containing 20 % NiSO4 was calcined and evacuated at 500 ℃. The high catalytic activity of NiSO4/TiO2-ZrO2 was related to the increase of acidity and acid strength due to the addition of NiSO4. The asymmetric stretching frequency of the S=O bonds for NiSO4/TiO2-ZrO2 samples was related to the acidic properties and catalytic activity. |
