PROPENE OLIGOMERIZATION CATALYST DERIVED FROM NICKEL SULFATE SUPPORTED ON GAMMA-ALUMINA

NiSO4/gamma-Al2O3 catalysts were prepared by impregnation and calcined in dry air at 450-600-degrees-C. The catalysts loaded with 2.5-10 wt.-% of nickel, show very high oligomerization activities for porpene. Under the conditions of 30-degrees-C, 2.5 MPa and liquid hourly space velocity 2 h-1, propene conversions are about 98%, and dimerization selectivities are 55-80%. These catalysts also show high activity and dimerization selectivity at lower temperatures, at 0-degrees-C and liquid hourly space velocity 1 h-1, the conversion and the selectivity are about 90 and 82%, respectively. It has been found by transmission electron microscopy and X-ray diffraction that when the loading of nickel is no more than 8 wt.-%, a monolayer of NiSO4 was found on the surface of gamma-alumina. Acid strength distributions of variously loaded catalysts were determined by means of butylamine titration. From infrared spectroscopy characterization, only Lewis-acid sites were observed on the surface of the catalyst.