Fabrication of Ionic Liquid-Based Pickering Emulsion and Its Enhancement for Tri-isobutene Formation in Isobutene Oligomerization
journal contributionposted on 19.05.2020, 19:14 by Lunchao Lv, Hongyan Wang, Jian Chen, Yingying Cao, Hui Wang, Baozeng Ren, Suojiang Zhang
Nanoparticles resistant to strong acid were prepared by grafting alkyl chains (i.e., C1–, C8–, and C18−) and alkyl sulfonic acid groups onto silica. The composition, morphology, and contact angles of these nanoparticles were characterized. These modified silica nanoparticles were used to fabricate a Pickering emulsion using the mixture of concentrated sulfuric acid and ionic liquid as the water phase and alkane as the oil phase. The effects of nanoparticle structure, ionic liquid concentration, emulsifier content, storage time, and temperature on the physicochemical properties of the emulsion were investigated. It was illustrated that emulsions constructed by C8–SiO2–SO3H (octyl and propylsulfonic acid groups modified silica) were more stable. As the concentration of ionic liquid increased, the droplet size of the emulsion gradually increased. Conversely, the increase of the alkyl chain of the oil phase resulted in a decrease of the droplet size of the emulsion, and no obvious demulsification was observed when the emulsion constructed by C8–SiO2–SO3H was stored at room temperature for 14 days or when the temperature was increased to 80 °C. This kind of emulsion was used to improve the product distribution of isobutene oligomerization under mild conditions. It was found that compared with the system containing no emulsion, the weight percentage of tri-isobutene (C12=) in the product could be enhanced by 4.8% at 40 °C in 60 min, and that of C12= and C16= was increased by 10.5%.