Synthesis Of Cyclohexylbenzene From Benzene Andcyclohexene

Cyclohexylbenzene is an important organic intermediate in the chemical industry,which has a wide range of roles in various fields of the fine chemical industry.Among its numerous synthesis methods,the current synthesis of cyclohexylbenzene from benzene is a synthetic pathway that has been studied for many years.However,the efficiency of benzene hydrogenation to produce cyclohexylbenzene is low and difficult to improve.At the same time,clean chemical and green chemicals are strongly advocated.This article uses the synthesis method of benzocyclohexene and attempts to screen and apply a clean solid catalyst.Under suitable conditions,the catalysts with high catalytic performance,good stability and simple preparation process for screening cyclohexylbenzene for cyclohexene synthesis are used as one of the objectives of this paper.At the same time,the reaction conditions were optimized,and the catalysts were characterized by BET,NH₃-TPD,SEM,XRD and Pyridine infrared.The thermodynamics of this reaction was simply analyzed.The specific work is as follows:?1?The thermodynamic properties of typical side reactions in the reaction of synthesis of cyclohexylbenzene from benzene and cyclohexene were studied.Thermodynamic analysis showed that cyclohexylbenzene was synthesized mainly under 460 K.At this time,the equilibrium constant was higher.Above this temperature,a large amount of by-products were generated.Supported the study of this article,and provided the theoretical basis for the industrial synthesis of cyclohexylbenzene.The separation of main products and byproducts was simulated using the simple distillation module DSTWU in Aspen Plus.By calculation,the minimum reflux ratio of the distillation column is 1.04,the actual reflux ratio is 1.57,the minimum theoretical plate is 4 pieces,the actual theoretical number of theoretical plates is 20,and the 11th plate is fed.?2?A series of molecular sieve catalysts such as ZSM-5-AT,MCM-22-AT,MCM-41-AT,USY-AT,and NaY-AT were prepared by acid leaching.This series of catalysts and untreated ZSM-5,MCM-22,MCM-41,USY,and NaY molecular sieves were used in the reaction of benzene and cyclohexene to synthesize cyclohexylbenzene?CHB?,respectively.With the CHB yield as an index,the best catalyst was determined by impregnation method.A series of single-factor experiments and orthogonal experiments were performed to optimize the reaction conditions.The yield of cyclohexylbenzene was 76.56%when the amount of catalyst was 2.5 wt%,phenene ratio was 10:1,reaction pressure was 3 MPa,reaction temperature was 150°C,reaction time was 4 h.?3?HPW-USY catalyst,HPMo-USY catalyst,HsiW-USY catalyst were prepared based on the screened USY molecular sieves.It was found that the HPW-USY catalyst has a good catalytic effect,and the preparation process of this catalyst was optimized by orthogonal experiments.The optimized conditions for preparing the catalyst were as follows:calcination temperature 400°C,calcination time 4 h,pH 1and ratio of phosphorus to tungsten was 1:12.Afterwards,the effect of each process condition on the reaction was explored by a combination of single-factor experiments and orthogonal experiments.The optimum process conditions were determined as follows:benzeneene ratio 12:1,reaction time 3 h,reaction pressure 3 MPa,reaction Temperature 150°C.Under the optimal conditions,the yield of CHB can reached95.68%,and after the catalyst was reused seven times,the yield of CHB was still as high as 83.5%.The prepared catalyst has high catalytic activity and reproducibility for the reaction of benzene and cyclohexene to prepare cyclohexylbenzene.?4?The HPW-USY catalysts were characterized by BET,TG-DSC,SEM,XRD and NH₃-TPD.It was found that there were micropores on the surface and weak acid sites existed.Its skeleton characteristic peaks remain intact,and the crystallinity is reduced compared to the USY molecular sieve.