Alkylation of isobutane with butene catalyzed by deep eutectic ionic liquids

The alkylation process of iso butane with butene is important in the petroleum industry. Ionic liquids (ILs) are considered as attractive alternative catalysts for iso butane alkylation besides strong liquid acids (H 2 SO 4 or HF) and solid superacids. In this study, ILs based on amides-aluminum chloride (AlCl 3 ) were synthesized and characterized, which exhibited both Lewis and Brønsted acidities. These deep eutectic ILs were found to be efficient catalysts for iso butane alkylation. The influences of the amide substrate, AlCl 3 /amide molar ratio, and metal additive on Lewis and Brønsted acidities were observed together with the synergetic effect of Lewis and Brønsted acid sites in the catalytic process. CuCl modified Urea-1.6AlCl 3 showed the best catalytic performance. The butene conversion was about 99.9% and C8 selectivity reached 57.6% under optimized reaction conditions (temperature of 15 °C, stirring rate of 1500 rpm, hydrocarbon feeding rate of 300 mL/h, iso butane/olefin molar ratio of 15:1, and reaction time of 15 min). In addition, Urea-1.6AlCl 3 -0.13CuCl could be recycled and reused for at least 20 times without obvious loss in catalytic activity.