Improved Catalytic Lifetime of H₂SO₄ for Isobutane Alkylation with Trace Amount of Ionic Liquids Buffer

Abstract

Trace amounts of ionic liquids have been mixed in sulfuric acid to enhance the catalytic performance for the alkylation of isobutane with butene. The experimental results from batch reactors indicated that the reaction efficiency was significantly improved. The effective catalytic lifetime of concentrated H 2 SO 4 mixed with [Bmim][SbF 6 ] was twice compared with pure H 2 SO 4 . Under the optimal conditions, the alkylate research octane (RON) reached 98, and the selectivity of C8 was 90%. The ionic liquids with SbF 6 anion worked similar to buffer agents, which were in favor of keeping the acid strength of catalytic system, slowing the growth of acid soluble oil, and reducing acid consumption. In conclusion, the new catalytic system of acid and trace amounts of ionic liquids is very promising to substitute the old catalytic system of concentrated H 2 SO 4 alone for the alkylation.

Droplet formation of H2SO4/alkane system in a T‐junction microchannel: Gravity effect

“…Few studies on the microdispersion performance of some systems, such as concentrated sulfuric acid (H 2 SO 4 ) and alkane system, have ever been reported. However, H 2 SO 4 is a common acid catalyst and widely used in the industrial processes, such as alkylation, rearrangement, and Claisen–Schmidt reaction . Applications in microchannels with H 2 SO 4 have been extensively investigated .…”

Ionic liquids and supercritical carbon dioxide: green and alternative reaction media for chemical processes

“…Trace amounts of ILs were mixed with sulfuric acid to enhance the catalytic performance. Compared with a solely sulfuric acid catalyst, the alkylation reaction rate doubled, and the lifetime prolonged by one time with the [C4mim][SbF 6 ]-H 2 SO 4 synergistic catalytic system (Huang et al 2015). The ILs with a SbF 6 -anion worked as a buffer agent, which were in favor of retaining the acid strength of the catalytic system, slowing the formation of acid soluble oil and reducing acid consumption.…”

Understanding interfacial behaviors of isobutane alkylation with C4 olefin catalyzed by sulfuric acid or ionic liquids

“…One of the most appealing advantages of ILs used as catalysts for the alkylation is that they can obviously improve the interfacial properties and the solubility of hydrocarbons in acid phase compared to H 2 SO 4. For example, the solubility of isobutane in the [BMim][PF 6 ] and [BMim][BF 4 ] reported by Zhang et al was 0.245 and 0.251 wt % at 25°C, respectively, while it is only 0.044 wt % in the H 2 SO 4 under the same conditions . Furthermore, due to the nano‐structuration of ILs composed of polar and nonpolar domains, the ILs with longer alkyl chains possess quite a lot common characteristics with surfactants and can greatly enhance the solubility of isobutane, and thus improve the quality of alkylate.…”

“…In recent years, considerable attention has been focused on ionic liquids (ILs) as an alternative and promising catalyst, such as its application in the alkylation due to their outstanding advantages, including Lewis and Brønsted acidity, negligibly vapor pressure and easy separation from the products . Due to the excellent Lewis acidic properties, the chloroaluminate‐based ILs have been the most frequently investigated substitutes to catalyze the alkylation with better catalytic performances .…”

“…For instance, the selectivity of trimethylpentanes (TMPs) of alkylate using chloroaluminate‐based ILs as catalysts reported by Liu et al was up to 87.5 wt % and the corresponding RON reached 100.5. Alternatively, the Brønsted acidic ILs have been proved to be a promising cocatalyst for the alkylation, which can enhance the activity and stability of the strong acid . Compared to the H 2 SO 4 , the binary mixtures of Brønsted acidic ILs/strong acids reported by Tang et al showed an outstanding catalytic performance with the optimized selectivity of C 8 ‐alkylates up to 75.8 wt%.…”