Preparation of NiO-ZrO2/SO 4 -2 catalyst and its catalytic activity for ethylene dimerization

NiO-ZrO₂/SO ₄ ^-2 catalysts were prepared by coprecipitation from the solution of nickel chloride -zirconium oxychloride mixture followed by treating with H₂SO₄ NiO-ZrO₂ alone without SO ₄ ^-2 was inactive as a catalyst for ethylene dimerization, but NiO-ZrO₂/SO ₄ ^-2 was found to be very active even at room temperature. The high catalytic activity of NiO-ZrO₂/SO ₄ ^-2 was closely correlated with the increase of acid strength by the inductive effect of sulfate ion adsorbed on NiO-ZrO₂. The decrease of catalytic activity above 150‡C of evacuation temperature was explained in terms of the structural change of catalyst from amorphous phase to crystalline, and the sintering.