Triflic acid catalyzed continuous alkylation of isobutane and butene with ionic liquids as a promoter NHaifang LiDState Key Laboratory of Multiphase Complex System, Beijing Key Laboratory of Ionic Liquid Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China

摘要

Processes for the alkylation of isobutane with C3-C5 olefin to produce the highest quality gasoline are of considerable industrial importance, which form a highly branched C8 paraf?ns mixture with high research octane number (RON) and free of sulphur and aromatics. However, the industrially used catalysts (sulfuric acid or hydrogen ?uoride) for alkylation are “non-green” because of some drawbacks from an environmental as well as toxicological point of view. An improved process for the continuous alkylation of isobutane and butene in the presence of the acidic ionic liquid catalysts which could be effectively tuned physical-chemical properties of the catalytic systems containing the acidity, solubility, density, viscosity, interfacial properties and so on were reported in this study. In the batch reaction, the acidic ionic liquids catalysts have been prepared from the quaternary ammonium-based ionic liquids with varied anion (such as BF_4~- , PF_6~- SbF_6~-or NTf_2~- ) and triflic acid. In addition, several additives, including metal triflates, trifluoroethanol, PPh3 and so on, were used further to improve the catalytic performances.?High-quality alkylate with up to 90% C8 selectivity and 98 RON value were achieved with the optimized catalyst and operation condition. In the continuous reaction, ICP-Mass and ultraviolet-fluorescence analyzer were used to study the alkylate quality. UV-vis spectroscopy and ~(13)C-NMR were used to determined the acidic scale of catalytic system. In addition, refractive indexes also were used to refracted the changing trends of the catalytic composition and catalytic performance in the continuous process.