Study On The Alkylation Proccess Of P-xylene And 1-tetradecene Catalyzed By Ionic Liquids

Alkyl aromatic is an important kind of chemical materials,which is widely used in daily chemical industry,petrochemical industry,organic chemical industry,etc.At present,hydrofluoric acid is mainly adopted as catalyst in the alkylation process of aromatics in China,which has the disadvantages of the corrosivity and potential environmental hazards.Because the 2-phenyl isomer(2-HAB)and its subsequent product can biodegrade easily,the heavy alkylbenzene product with high content of 2-HAB isomer has huge demand in the market.However,it is difficult to control the regioselectivity in the process of reaction.In order to solve these problems,a great deal of efforts have been made to explore environ-mentally friendly and efficient aromatic alkylation technology.Acidic ionic liquids have the advantages of thermal stability,nonvolatile,high reactivity,active stability and superacidity,and exhibit the potential to replace hydrofluoric acid and solid acid as catalysts of aromatic alkylation process.In this work,the alkylation reaction of p-xylene and 1-tetradecene was taken as an example to study the influence of various process parameters on the conversion of raw materials,yield of the target product and selectivity of 2-HAB isomer in stirred tank reactor.The quantitative analysis of reaction products was carried out by Gas Chromatography(GC).The reaction products were characterized with infrared spectrum(IR),mass spectrum(MS)and nuclear magnetic resonance(NMR).The main results are as following:(1)After preliminary Screening of catalysts,the composite ionic liquid and 1-butyl-3-methylimidazolium chloroaluminate ionic liquids were selected to be used in the following experiments.The catalytic performances of the two catalysts were compared.When the composite ionic liquids were used as catalyst,the selectivity of 2-HAB isomer was higher.When 1-butyl-3-methylimidazolium chloroaluminate ionic liquids were used as catalysts,the yield of the target product was higher.(2)These two factors,the yield of the target product and the selectivity of 2-HAB isomer,should be taken into consideration.When the composite ionic liquids were used as catalysts,within the scope of the experiment the optimized reaction conditions were as following:T=40?,px/O=8:1(mol:mol),O/IL=2:1(m:m),N=2400r/min,t=7min,The dropping time of 1-tetradecene is 5min.Under these conditions,the conversion of 1-tetradecene reached 99.56%.The total yield of the target product was 94.16%,and the selectivity of 2-HAB isomer was 57.68%.(3)These two factors,the yield of the target product and the selectivity of 2-HAB isomer,should be taken into consideration.When 1-butyl-3-methylimidazolium chloroaluminate ionic liquids were used as catalysts,within the scope of the experiment the optimized reaction conditions were as following:T=32?,px/O=9:1(mol:mol),O/IL =4.5:1(m:m),N=2400 r/min,t=7min,The dropping time of 1-tetradecene is 5min.Under these conditions,the conversion of 1-tetradecene reached 99.43%.the total yield of the target product was 95.3%,and the selectivity of 2-HAB isomer was 50.35%.