Investigation Of Isobutene Oligomerization For Producing Diisobutene

With the rapid development of aviation industry, the requirement of high quality unleaded avags was rising, and2,2,4-trimethylpentane with high purity is the indispensable component of unleaded avags. Indirect alkylation using isobutene as raw material can obtain high purity2,2,4-trimethylpentane. In order to satisfy the produce of high quality avags, the development and application of indirect alkylation was very important. Isobutene dimerization over macroporous sulfonic resin is mainly investigated in this dissertation.Firstly, the effects of reaction conditions on isobutene oligomerization were investigated. Secondly, sulfonic resin catalyst with different acid capacity through Na+exchange was prepared. Metal-acid dual function catalyst was also prepared by Ni2+exchange. The dimerization performance of the two kinds of catalysts was evaluated. The influences of the addition of CH3OH and methyl tert-butyl ether (MTBE) into feed on isobutene oligomerization over Amberlyst15were investigated. The oligomerization performance of isobutene over Amberlyst15of mixed C4butenes as feed was studied. The kinetics model of isobutene oligomerization over Amberlyst15was established.Experimental results showed that the decrease of acid capacity and reaction temperature or increase of LHSV significantly improved the diisobutene (DIB) selectivity at the cost of the decrease of isobutene conversion. Under proper reaction temperature and exchange ratio, Ni+interacted with acid sites, which led to an enhancement of the DIB selectivity and inhibited the generation of tetramers. The addition of1-butene to isobutene feed resulted in the reduction of the conversion of isobutene and codimerization with isobutene to dimethyl-hexene. The addition of polar molecules of CH3OH and MTBE into isobutene feed obviously improved the DIB selectivity. The improvement role of CH3OH lied in the etherification reaction between CH3OH and isobutene, while the role of MTBE lied in the adsorption of MTBE on the acid sites to decrease the adsorption of isobutene. Under optimum reaction conditions, the DIB selectivity was increased up to96.9%when the molar ratio of methanol to isobutene was0.6. Kinetic model indicated that the activated energy of isobutene dimerization and trimerization was63.1kJ/mol and33.0kJ/mol, respectively, pre-exponential factor was1.61X108min-1and5.89X104min-1, respectively.