| Catalytic behavior of NiSO4/~y-Al2O3 catalyst prepared by impregnated in hexene oligomerization has been studied. The results show NiSO4/y-A1203 catalyst has very high catalytic activity and good selectivity for dimer.The reactivity sequence of alkene oligomerization is ethane> propene>butene > hexane. This sequence is quit different from that of the ordinary acid catalyzed reaction.Conditions of catalyst preparing have a considerable effect on its properties. The surface acidity of the catalyst increases with increasing calcinations temperature, and a maximum appears at 893K, which is approximately paralleled by the change of the activity of hexene oligc)merization over the catalysts. It shows the acidity of the catalyst play a very important role in the catalytic behavior. When the calcination temperature is higher than 6000C, the activity is lowed. This is probably due2+to the occurrence of a solid phase reaction between Ni and -A1203 forming NiAI2O4.The NiSO4 on the surface is homogeneously distributed, possibly monolayer, for nickel loading not exceeding 8wt.%. Medium strong acid (H0 ~-3.O) exhibits a maximum at nickel-loading 8wt.%. That is similar to the change of activity of hexene oligomerization with the loading.Acid strength distribution of the catalysts determined by butylamine titration indicates that the active catalysts all possess medium strong acidity HO<-3.O and that the inactive catalysts have very weak or no acidity. It can be seen that support effect mainly relates to the acid-base property of the itself or the acidity generated after interaction with NiSO4.Comparision between NiSO4 and other sulfate shows its aciditysequence in A12(S043 > (NH4)2S04 > NiSQ4, which is not same as that of catalytic activity.The activity of the catalyst for hexane oligomerization increases with increasing reaction temperature, and a maximum appears at 393K.The hexene conversion remains constant in range from 0.5W?to 2.0W? but it decreased when LHSV exceeds 2.5W?...
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