Preparation of alkylate gasoline in polyether-based acidic ionic liquids

Abstract

A series of novel polyether-based Brønsted acidic ionic liquids (ILs) have been synthesized, which contain both a polyoxyethylene (POE) chain and a sulfonic group (SO3H). The prepared ILs can well dissolve trifluoromethanesulfonic acid (TfOH), and IL/TfOH mixture has good intermiscibility with the reactants of isobutane and isobutene. Then, a new IL/TfOH catalytic system for the preparation of alkylate gasoline has been developed. The advantages of the new catalytic system are high selectivity for C8-alkylate product and the recyclability of TfOH catalyst. Under the optimal catalytic conditions (using the IL with the polymerization degree n=75, IL/TfOH(v/v)=5, reaction temperature 60°C, reaction time 30min, and stirring rate 800rpm), the C8-selectivity can reach 80%, and above 95% of C8-alkylate product is trimethylpentane (TMP). Therefore, the new IL/TfOH catalytic system can afford high-quality alkylate gasoline. In addition, the conversion of isobutene and C8-selectivity both have gradually a little drop during 6 recycles, which should attribute to a little loss of TfOH in every recycle.