Abstract: The effects of reaction conditions, such as temperature, space velocit y have been investigated in liquid-phase isobutene oligomerization over Nafion at 1.8 MPa. The catalyst stability and the character in the reaction have been discussed also. The isobutene conversion is enhanced with the increase of reacti on temperature rapidly in the range of 30～60 ℃, and the main liquid products a re the dimmer; whereas the main products are the trimmer at the reaction temper ature higher than 60 ℃, the isobutene conversion is higher than 86%. The catalytic activity of Nafion increases with the increasing of accessible sulfonic group. High temperature profits to en hance the swelling capacity of Nafion and makes the bulk phase more accessible. Furthermore, the increase of accessible acid sites caused by temperature is sta ble and irreversible. It can be restored by lower temperature treatment for long time. More diisobutene can be obtained at a low temperature over silica-suppor ting Nafion.

Key words: isobutene, oligomerization, solid acid, Nafion