Alkylation mechanism of benzene with 1-dodecene catalyzed by Et3NHCl-AlCl3

Synthesis of alkylbenzenes via the alkylation of benzene using α-olefin dimers and the surfactant properties of their sulfonates

Fischer-Tropsch syncrude prepared via the Fischer-Tropsch synthesis (FTS) using a Fe-based catalyst is featured by its high content of linear α-olefins (C5–C13). The utilization of C6–C8 α-olefins for the synthesis of alkyl benzene sulfonate surfactants was performed in the present work via dimerization, benzene alkylation, and sulfonation. The effects of the reaction conditions on benzene alkylation over a trimethyl amine hydrochloride-acidic anhydrous aluminum chloride ionic liquid catalyst (Et3NHCl-AlCl3) have been studied in detail using C6 α-olefin dimers as a model alkylation agent. Under the optimal reaction conditions (molar ratio of AlCl3 to Et3NHCl = 2, catalyst loading = 0.29 mol %, reaction temperature = 30 °C, and molar ratio of benzene to C6 α-olefin dimer = 10) the conversion of the C6 α-olefin dimer was 100% and the selectivity toward the mono alkylbenzene product was 91.0%. C6–C8 α-olefin dimer alkylbenzene sulfonates (C6–C8 DBS) were synthesized via sulfonation using chlorosulfonic acid and characterized using Fourier Transform Infrared (FT-IR) spectroscopy and Liquid Chromatography–Mass Spectrometry (LC–MS). The surfactant properties of the C6–C8 DBS, including their equilibrium and dynamic surface tension, foaming, wetting and emulsifying capabilities, were closely explored and compared with a commercial linear alkylbenzene sulfonate (LAS). The limiting surface tension (γ CMC = 34.62 mN m−1) and critical micelle concentration (CMC = 2.15 mmol L−1) of C6 α-olefin dimer alkylbenzene sulfonate (C6-DBS) were similar to those of LAS. Upon increasing the hydrocarbon chain length, the γ CMC of C6-DBS, C7-DBS, and C8-DBS remained unchanged, while the CMC decreased. C6–C8-DBS exhibited foaming, emulsifying, and wetting properties comparable to LAS.

Effect of surface silicon modification of H-beta zeolites for alkylation of benzene with 1-dodecene

H-beta zeolites of 100–200 nm (named BEA-L) and 20–30 nm (named BEA-S) were treated by chemical liquid deposition (CLD) of tetraethyl orthosilicate (TEOS) to improve the selectivity of 2-phenyl linear alkylbenzene (2-LAB) from benzene alkylation with 1-dodecene. The results indicate that H-beta zeolite with a smaller crystal size has a longer lifetime due to shorter channels and less diffusion limitation. The deposited SiO₂ layers passivated the external surface acid sites of the zeolite and made the pores narrower. BEA-L lost more external Brønsted acid sites than BEA-S with the same added amount of TEOS, which was due to the severe aggregation of BEA-S grains. This increased passivation gave BEA-L increased 2-LAB selectivity. And when the added amount of SiO₂ was 7.20 wt% of the parent zeolite, the selectivity of 2-LAB over BEA-L significantly increased from 41.9% to 54.7% while that of BEA-S only increased by 2%.

β zeolite with large grain size has higher external surface acid passivation efficiency while that of β zeolite with small grain size is very low due to severe agglomeration.

Durability enhanced ionic liquid catalyst for Friedel–Crafts reaction between benzene and 1-dodecene: insight into catalyst deactivation

Friedel–Crafts alkylation of benzene with 1-dodecene, which is an important reaction of synthetic detergent, was studied using the durability enhanced catalyst [bmim][TFSI]/AlCl₃ (1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide/AlCl₃).