Alkylation Of Benzene With 1-dodecene Catalyzed By Ionic Liquid: Et₃HNCl-xAlCl₃

As a new type of environmentally friendly catalyst,ionic liquid has showed good catalytic performances in alkylation reactions.Inorganic catalysts and solid acid catalysts have been used in the production of linear alkyl-benzene for a long time,but their common drawbacks of reaction are at high temperature and low level of selectivity of 2-alkylbenzene?2-LAB?.Room temperature ionic liquids are applied to solve these problems by people on account of high activity at low temperature.This thesis is focused on the application of chloroaluminate ionic liquid named[Et₃NH][Al_xCl_3x+1]as the catalysts in alkylation reaction of benzene with 1-dodecene.The effect of influencing factors was investigated,such as the constitution of ionic liquid,the dosage of catalyst,the mole ratio of benzene to 1-dodecene,temperature and reaction time.Also,the effects of alkyl chain length in different and the reuse efficiency of the catalyst were discussed.Furthermore,additive and adding olefin method were studied too.A range of experimental results show that ionic liquid is characterized in high catalytic efficiency,the conversion of olefin is higher than 99.7%.The increase of these factors rise the yield of monoalkyl benzene in varying degrees,include of the aluminium chloride content in ionic liquid,the dosage of catalyst,the mole ratio of benzene to 1-dodecene,temperature and reaction time.Among thses ways,the 2-LAB selectivity decrease with exorbitant aluminium chloride content in ionic liquid or the increase of the reaction temperature.Long carbon chain makes it difficult for a-olefins to trigger muti-alkylation of alkylbenzene,which causes the rise of the monoalkyl benzene yield,while the decline of the 2-LAB selectivity.Moreover,the study proves that the ionic liquid is characteristic in repeated use within a certain range.Modification Studies have been taken by using different additives under the optimal reaction conditions.The increase of chlorine ion?Cl-?will lessen the number of active sites which is Lewis base.Massive potassium ion?K+?will depress the 2-LAB selectivity which isn't Lewis acid.When several transition metal chloride MCl(M=Fe³⁺,Zn²⁺,Cu²⁺,U,Cu⁺,Ni²⁺)was added to the ionic liquid,the experiment resulted that some additives that have strong Lewis acids and whose coordination numbers minus the lost electrons number more than two,promote muti-alkylation of alkylbenzene.At the same time,the productivity of monoalkyl benzene comes down.Some additives that have faintly Lewis acids raise the productivity of monoalkyl benzene.Adding additives make the selectivity of 2-LAB show varying degrees of decline.The productivity of monoalkyl benzene and the selectivity of 2-LAB can get a promotion by changing the technological conditions:The productivity of monoalkyl benzene and the selectivity of 2-LAB can get a promotion by changing the technological conditions:Change the way that 1-dodecene is added in a whole to dripping.The change sustained the molar ratio of benzene to olefin at higher levels during the reaction.