| In this dissertation, the preparation of Aid3 immobilized catalyst (AC-i) and its performance in the selective polymerization of isobutene in C4 petroleum fraction was investigated. The AC-i catalyst was prepared by reacting A1C13 with y-Al203. It contains about 7.4wt% AlCi~and the value of x is 2.2. This indicated that the structure of AIC12-O- is formed on the surface of AC-i. The influence of pore structure and particle size of the support y-A1203 on the performance of AC-i indicated that the polymerization process is controlled by internal diffusion. The macro,meso-duai pore structure and small particle size y-Al203 as a support can eliminate efficiently the influence of internal diffusion and raise the stability and activity of catalyst. The influence of reaction temperature and LHSV and the concentration of isobutene in the raw material on the polymerization of isobutene is significient. The conversion is about 94% and the selectivity is about 92% with the molecular weight of poiyisobutene about 1300 under such reaction conditions as T=300C, LHSV 2h?and the concentration of isobutene is 27.7%. The stability of AC- 1 is excellent . A long-term consecutive reaction was carried on at Th32棐340C, LHSV2W1 and Pl .OMPa. After i000h, the conversion remained 85%. Till 2000h, the conversion dropped to 57%. During the whole time, the selectivity and the molecular weight changed little and they were 90% and 1100, respectively. One of the important reasons that the catalyst lost its activity is that the active sites A1CI2-O- of AC-i is poisoned slowly by the little water in the raw material, called as 損erpetual deactivation? Another reason is produced by inner diffusion, called as emporary deactivation? The deactivate catalyst can be regenerated by chemical method with the saturated solution of A1C13 in Cd4 as the reagent for regeneration. The recovery rate of activity is over 96% and the stability can be the same as the fresh catalyst. |
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