Acidic-functionalizated Ionic Liquid Catalyzed Isobutane/Isobutene Alkylation Reaction

At present,the industrial catalysts such as concentrated sulfuric acid,hydrofluoric acid and zeolite molecular sieves used in the preparation of alkylate gasoline by isobutane/butene alkylation have the disadvantages of high acid consumption,serious environmental pollution and rapid deactivation.Three kinds of acidic-functionalized ionic liquids were designed and synthesized in this paper.The alkylation reaction of isobutane with isobutene was designed to prepare high-octane alkylate gasoline.The structure of the ionic liquid was characterized by FT-IR and 1H NMR.The stability of the ionic liquid was determined by thermogravimetric analysis(TG-DTG).Three catalytic systems are studied including(1)Br?nsted-Lewis acidic-functionalized ionic liquids catalyzed alkylation of isobutene with isobutene;(2)Lewis acidicfunctionalizedionic liquidscatalyzed alkylation of isobutane with isobutene;(3)Br?nsted acidic-functionalizedionic liquids catalyzed alkylation of isobutene with isobutene.A series of Br?nsted-Lewis acidic-functionalized ionic liquids were designed and synthesized by using N-methylpyrrolidone,hydrochloric acid and aluminum trichloride as raw materials and used in catalyzing the alkylation of isobutane with isobutene.The best catalyst for the catalytic preparation of alkylate gasoline was[Hnmp]Cl-1.6AlCl3.The effects of reaction temperature,reaction time,amount of ionic liquid,reaction speed on the alkylation of isobutane were investigated.The optimum reaction conditions were as follows: the mole ratio of isobutane to isobutene10: 1,the reaction raw material 30 mL,[Hnmp]Cl-1.6AlCl3 20 mL,the reaction temperature 25 ?,the reaction time 30 min,the reaction speed 800 r/min.The conversion of isobutene was 100%,and the selectivity of C8-product was 34.54%.Under the optimum conditions,the recycling life of the catalyst was investigated.The catalyst [Hnmp] Cl-1.6Al Cl3 was recycled seven times,and its catalytic activity was basically unchanged.A series of Lewis acidic-functionalized ionic liquids were designed and synthesized by using acetamide,urea and aluminum trichloride as raw materials and used in catalyzing the alkylation of isobutane and isobutene.The optimum catalyst was CH3CONH2-1.6AlCl3.The effects of reaction temperature,reaction time,the amount of ionic liquid,addition of metal inhibitor,reaction speed on the alkylation of isobutane were investigated.The optimum reaction conditions were as follows: the reaction raw material 30 mL,the ionic liquid CH3CONH2-1.6AlCl3 10 mL,the reaction temperature 10 ?,the reaction time 30 min,the ratio of the metal inhibitor CuCl to the ionic liquid 0.5,and the reaction speed 1000 r/min.The isobutene conversion was 99%,and the selectivity of C8-product was 40.92%.Catalyst CH3CONH2-1.6AlCl3 was recycled nine times,and the catalytic activity was basically unchanged.A series of Br?nstedacidic-functionalizedionic liquids with different degrees of polymerization were designed and synthesized by using di-n-hexylamine,ethylene oxide,1,3-propane sulfonic acid lactone and trifluoromethane sulfonic acid as raw materials.Its application for catalytic isobutane/isobutene alkylation reaction has showed a good catalytic activity and a good cycle life.The physical properties such as viscosity,density and polarity of the catalyst were studied.The effects of reaction temperature,reaction time,catalyst dosage,rotation speed and additives on the reaction were investigated by catalytic reaction of isobutane/isobutene with the best catalytic ionic liquid [PS-DHA-75] TFO as a catalyst.The optimum conditions were as follows: the volume ratio of [PS-DHA-75] TFO totrifluoromethane sulfonic acid 5: 1,the mole ratio of isobutane to isobutene 10: 1,the reaction raw material 30 mL,the reaction temperature 60 ?,the reaction time 30 min.The conversion of isobutene was86% and the selectivity of C8-productwas 85.92% when the reaction speed was 800r/min and the amount of tert-butyl bromide was 0.5 g.The acid strength of the ionicliquid coupling with trifluoromethane sulfonic acid was determined and found to be low,but the mixture still afforded good conversion and selectivity.The catalyst was recycled six times,its catalytic activity was basically unchanged.In this paper,three different types of acidic ionic liquids were successfully synthesized and used in the preparation of alkylate gasoline with isobutane/isobutene alkylation for the first time.Good catalytic activity was achieved,and the catalyst and the product were effective separated giving a good recycling performance.This paper provides a new scientific basis for the application of acidi-functionalized ionic liquids in the catalytic alkylation.It also provides a new way to catalytic preparation of high-octane alkylate gasoline.