Characterization and catalytic activity for ethylene dimerization of nickel sulfate supported on zirconia

A series of catalysts, NiSO4/ZrO2, for ethylene dimerization were prepared by the impregnation method using aqueous solutions of nickel sulfate. The results obtained from X-ray diffraction and DSC indicate that the addition of NiSO4 Shifted the transition of ZrO2 from amorphous to tetragonal phase toward higher temperatures due to the interaction between NiSO4 and ZrO2. Nickel sulfate supported on zirconia was found to be very active even at room temperature. The high catalytic activity of NiSO4/ZrO2 was closely correlated with the increase of acidity and acid strength due to the addition of NiSO4. The active sites responsible for ethylene dimerization may consist of low-valent nickel, Ni+ and an acid. (C) 2002 Elsevier Science B.V. All rights reserved.