Dual-site eutectic ionic liquids based microemulsion for boosting selective dimerization of isobutene

Oligomerization is one of the efficient routes for making use of C4 olefins to produce high value-added chemicals. However, high reagent conversion is usually accompanied by low dimer product selectivity, and vice versa. Ionic liquids (ILs) with intense interaction between Lewis and Brønsted acidic sites were demonstrated to be excellent catalysts for butene oligomerization. Furthermore, it was found that eutectic IL could be formed by strong hydrogen bond when alcohol was added to the IL, which exhibited enhanced butene solubility and thus improved catalytic performance. Moreover, microemulsion could be constructed by adding an IL emulsifier into the IL catalyst, and the improved interfacial area further enhanced efficient contact between butene and catalyst. Combining the strategies of employing dual-site eutectic IL as the catalyst and microemulsion formation, butene conversion could reach 98%, while dimer selectivity was 91%, resolving the contradiction that high conversion and target product selectivity cannot be achieved simultaneously.