C4 Alkylation Catalyzed By Ionic Liquid/Sulfuric Acid

As the products of isobutane alkylation with butene catalyzed by strong acid,alkylate oil containing C8 isoalkanes is an ideal component for gasoline due to its high octane number,low vapor pressure,free from aromatics,olefins and sulfur.Sulfuric acid is the most used catalyst in C4 alkylation process.How ever,sulfuric acid C4 alkylation process has problems of huge acid consumption and waste acid treatment.In order to solve these problems,ionic liquids additives were introduced into the sulfuric acid catalyst to improve alkylate product based on interface enhancement.The experimental results showed that[OPSIm][HSO4]/H2SO4 and[Pr3NPS][HSO4]/H2SO4 had better catalytic activity.The optimal reaction condition was as follows:reaction time of 15 min,reaction temperature of 3? and acid/hydrocarbon ratio of 1:1.The optimal concentration of[OPSIm][HSO4]and[Pr3NPS][HSO4]in sulfuric acid was 100 mmol·L-1 and 200 mmol·L-1,respectively.The interface enhancement of ionic liquids at molecular scale was studied by molecular dynamic simulation.The results showed that the introduction of[OPSIm][HSO4]and[Pr3NPS][HSO4]can improve interfacial behavior.[OPSIm][HSO4]can contribute to a better dissolution of C4 hydrocarbons,especially isobutane,at the interface,thereby increasing isobutane/butene ratio,which is helpful to the quality of alkylate.[Pr3NPS][HSO4]can greatly increase the interface width,which is beneficial for increasing reaction rate.In addition,the custom user model based on C4 alkylation kinetics was established and integrated with ASPEN PLUS simulation platform to realize the process simulation of C4 alkylation process.The results regarding to influences of reaction temperature and butene types on C4 alkylation process showed that the octane number of alkylate product increased from 95.0 to 97.9 with the decrease of reaction temperature from 14? to 0?.2-Butene showed the best octane numb er of alkylate product,followed by 1-butene and isobutene.The research in this paper hopefully can provide theoretical basis for the design and optimization of new C4 alkylation process.