Liquid Phase Isobutane/2‐Butene Alkylation Promoted by Hydrogen Chloride Using Lewis Acidic Ionic Liquids

Abstract

In isobutane/2‐butene alkylation, chloroaluminate ionic liquid catalysts (CAIL) deactivate fast with time on stream with respect to activity and selectivity. Hence, the effect of anhydrous hydrogen chloride (HCl), which shows co‐catalytic behavior, was studied in a batch reactor and its effect on both parameters was investigated. The co‐catalyst leads to an increased reaction rate and improves the yield of trimethylpentanes, the primarily desired high‐octane compounds of alkylation. Moreover, already deactivated CAIL catalysts are reactivated by gaseous HCl. In addition saturation of the ionic liquid with HCl prior to the reaction effectively suppresses the deactivation of the CAIL catalyst. Thus, the solubility of hydrochloric acid is reported for both the CAIL (IL: [BMIM]Cl/AlCl3, x AlCl 3=0.64) and organic phase to gain a deeper understanding of the reaction system. Finally conjunct polymers dissolved in the ionic liquid were extracted to study their influence on deactivation.

Reaction performance of isobutane alkylation catalyzed by a composite ionic liquid at a short contact time

“… The first way is to adjust the acidity of ionic liquids by the addition of suitable amounts of Brønsted acid, for example by addition of a Brønsted acid, such as HCl, or by addition of a reagent that can produce Brønsted acid in reaction with the IL, such as H 2 O, or by addition of a functional group containing Brønsted acid, such as ‐SO 3 H. The addition of Brønsted acids to ionic liquids accelerates the carbocation formation by the addition of a proton to butene. The addition of anhydrous HCl into the ionic liquid bmimCl‐AlCl 3 can enhance reaction rate and improve both the TMPs selectivity and the alkylate RON, and the addition of anhydrous HCl is possible to reactivate a deactivated ionic liquid with respect to activity and selectivity . While the addition of large amount of HCl (5 mol %) to the ionic liquid Et 3 NHCl‐AlCl 3 is reported to increase the selectivity of C5–7 and to reduce the selectivities of C8 and C9+ .…”

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

“…A high content of the desired TMPs and, thus, a high RON of the alkylate were obtained by using triethylamine hydrochloride aluminum chloride ([Et 3 NH]Cl/AlCl 3 ) (molar fraction of AlCl 3 , 0.6). They have designed a batch reaction system for the application of this series of ILs, which contain HCl (Pöhlmann et al 2013 (Liu et al 2003. The retrofit increased not only the yield of the process (compared to sulfuric acid) but also the process unit's capacity by 40% (to 248 tons/day), with attractive economics.…”

Alkylation of isobutane/isobutene using Brønsted–Lewis acidic ionic liquids as catalysts

“…However, these ILs only possess Lewis acidity and their acidities were not adjusted, which is unfavorable when selecting an efficient catalyst for the reaction. Therefore, some compounds, such as Brønsted acid (hydrochloric acid or the Brønsted acidic IL, 1-methyl-3-(4-sulfobutyl)-imidazolium hydrogen sulfate [HO 3 Sbmim][HSO 4 ]) [16,17], alkyl halide (tert-butyl chloride) [15] and metal salt (CuCl, CuCl 2 , or NiCl 2 ) [18] have been used as co-catalysts to improve the catalytic performance of ILs. The results show that this was an effective way to improve the activity and selectivity of a Lewis acidic IL.…”