CuCl2-modified ionic liquids for alkylation of benzene with 1-dodecene

Abstract Benzene and 1-dodecene are often alkylated to produce linear alkylbenzene (LAB). LAB is the raw material for the production of linear alkylbenzene sulfonate (LAS), a very important anionic surfactant used in both industrial cleaning and commercial laundry processes, as well as in household laundry detergents. In the present study, we investigated the use of [Et3NH]Cl–2AlCl3 modified with CuCl2 as a catalyst for the alkylation of benzene with 1-dodecene, specifically looking at the effect of reaction conditions on product activity. The results showed that a conversion of 1-dodecene of 100.0 % and a selectivity of LAB of 93.79 % could be obtained when the following ideal reaction conditions were present: molar ratio of benzene/1-dodecene = 6, reaction temperature = 25 °C, reaction time = 10 min, stirring speed of 1000 rpm and addition of 5.0 mol % CuCl2). The catalyst concentration was 7.0 mol %. FTIR and 31P-TMPO-NMR measurements were performed to characterise the ionic liquid before and after the addition of CuCl2. After the addition of CuCl2, it was found that the acidity of the ionic liquid had decreased. The regeneration of the catalyst was also investigated and the cause of inactivation of the catalyst was determined. The results showed that CuCl2 modified the ionic liquids and decreased the benzene/1-dodecene ratio, but the high product selectivity was maintained.