Activity and stability investigation of [BMIM][AlCl 4] ionic liquid as catalyst for alkylation of benzene with 1-dodecene

Abstract

[1-butyl-3-methylimidazolium][tetrachloroaluminate] ([BMIM][AlCl 4]) ionic liquid was used to catalyze the alkylation of benzene with 1-dodecene to synthesize LAB, linear alkylbenzenes. The batch reaction performances were investigated using the orthogonal experimental method. It showed that the most important factor that governed the conversion of olefin and selectivity of LAB was reaction temperature. Moreover, the effects of molar ratio of AlCl 3 in ionic liquid to 1-dodecene and that of benzene to 1-dodecene on its conversion and selectivity are obviously in different degrees. The reaction temperature, molar ratio of benzene to 1-dodecene and the amounts of catalyst compared with the traditional reaction technologies were decreased. Further, the experimental results demonstrated that the ionic liquid catalyst had higher activity at 25 °C even if the molar ratio of AlCl 3 in ionic liquid to 1-dodecene and that of benzene to 1-dodecene were 0.07 and 8, respectively. Then, a continuous flow reactor equipped with a special bell type of settling–separating–discharging device was proposed. In this way the in situ separation of product mixtures from ionic liquid was realized and the stability of ionic liquid catalyst for the alkylation reaction was tested. A considerably longer running time of catalyst and higher efficiency were attained in the reactor adopted.