Study On The Preparation Process Of 2-tert-pentylanthracene

In the anthraquinone method,2-tert-Pentylanthraquinone is an efficient work carrier for the synthesis of hydrogen peroxide,which is traditionally prepared from benzene and phthalic anhydride by the benzene-anhydride process.Compared with the benzene-anhydride process,the 2-tert-pentylanthracene oxidation method has many advantages of simple procedure,mild reaction conditions and less environmental pollution due to not requiring the usage of concentrated sulfuric acid.However,the industrial application of the oxidation method is limited to less sources and difficult preparation.To address these problems,in this work,the preparation process of 2-tert-pentylanthracene was studied.The main contents can be summarized as follows:1.The preparation process by alkylation and transalkylation of anthracene were studied with the aluminum trichloride as catalyst.The effects of alkylation reagent,catalyst,solvent,molar ratio of reactants,temperature and time on alkylation were investigated.Furthermore,in order to recycle the by-products in the alkylation process,2-tert-pentylanthracene was prepared by transalkylation taking the main by-product,dipentylanthracene,as raw materials.The reactive conditons containing catalyst,solvent,temperature,time,and molar ratio of reactants on the reaction were also investigated and the suitable conditions of transalkylation process were obtained.2.Because aluminum trichloride is difficult to recycle and cause serious pollution problems,molecular sieves were used to catalyze the alkylation and transalkylation of anthracene.The modified preparation of molecular sieves and their catalytic performance were studied.(1)The alkylation reaction was catalyzed by acid-treated modified molecular sieves,and citric acid-modified MCM-22 molecular sieve was preferably selected to perform further reserch.The modified molecular sieves were characterized by XRD,FT-IR,NH3-TPD,N2 adsorption-desorption,ICP and SEM technologies.The influences of citric acid treatment times,the concentration of citric acid,solvent,temperature,pressure,time,catalyst dosage,and molar ratio of reactantwere investigated,and suitable reaction conditions were given.Under the optimized reaction conditions,the results showed the selectivity and yield of 2-tert-pentylanthracene were 82.6%and 44.0%,respectively.(2)Metal-supported modified molecular sieves were used to catalyze alkylation and the influences of different types of metal-supported molecular sieves on the catalytic performance were compared and Zirconium-based Beta molecular sieve was selected preferably.Then the preparation and catalytic activity of beta molecular sieve modified by Zr/Al bimetallic-citric acid compound were studied.The results presented the selectivity and yield of 2-tert-pentanthene were obtained to be 88.7%and 42.8%,respectively,when 20Zr/2Al-Beta(Si)-CA was used as a catalyst.(3)The modified molecular sieves were applied to catalyze the transalkylation of dipentylanthracene and the influences of the catalyst and temperature were investigated.The results showed that the highest yield of 2-tert-amylanthracene available was 68.6%when taking the MCM-22-CA as a catalyst.3.Aiming at the existing problems of isomerization and multisubstitution in alkylation,the alkylation products were separated by solid-liquid extraction combined with recrystallization then the target products(2-tert-pentylanthracene)and unreacted anthracene were obtained,respectively.The effects of solvent types and its quantity on the extraction efficiencies were studied and the effects of anthracene content and solvent on the recrystallization were also investigated.