Influence of Polar Components in the Dimerization of Isobutene

Isooctane is seen as a potential replacement for methyl tert-butyl ether (MTBE) in gasoline. Isooctane can be produced via the indirect alkylation route in two steps. Isobutene is first dimerized to isooctenes, which are then further hydrogenated to isooctane. In the dimerization a polar component is used to enhance the selectivity for diisobutenes. In this study the effects of tert-butyl alcohol (TBA), methanol and MTBE in the dimerization reaction were compared on the basis of experimental results. All the oxygenates studied induced similar effects: higher selectivity for diisobutenes and lower isobutene conversion as the oxygenate content increased and temperature decreased. The different polarity of the components causes the need for more methanol or MTBE than TBA to get the same conversion and selectivity.