Nanoparticles resistant to strong acid were prepared by grafting alkyl chains (i.e., C-1-, C-8-, and C-18-) 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 C-8-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 C-8-SiO2-SO3H was stored at room temperature for 14 days or when the temperature was increased to 80 degrees 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 (C-12(=)) in the product could be enhanced by 4.8% at 40 degrees C in 60 min, and that of C-12(=) and C-16(=) was increased by 10.5%.