Abstract: The Pd catalysts, using Al2O3 and alkali metal additives as carrier, were prepared by the kneading-impregnation method. The suitable alkali metal additive was chosen, the effects of additive amount and Pd loading on the olefin saturation activity of the catalyst were investigated. The process reaction conditions and activity stability of the selected catalyst were investigated. The results showed that the best alkali metal additive for the catalyst is Ca，and the best additive amount of Ca is 2.5% （w），meanwhile the best Pd loading is 0.15%（w）. The catalyst containing the additives has a less acid amount, and can reduce the aggregation of the diolefin on the catalyst surface, improving the stability of the catalyst. It is concluded by tests that the suitable reaction conditions for Pd/Ca-Al2O3 catalyst for hydrogenation of C5 raffinate are: 40 ℃，1.0 MPa， LHSV of 11 h-1，and the ratio of hydrogen to oil of 110. The olefin saturation rate of C5 raffinate under the optimal condition is not less than 99.5%，and the catalyst was continuously operated for 600 h with stable activity.

Key words: Pd catalyst, mixing-impregnation, C5 raffinate, stability, acidity