The Synthesis Of 2-ethylanthraquinone Over Solid Acids

2-Ethylanthraquinone(2-EAQ)is the main carrier of hydrogen peroxide in thesynthesis process.It is also an important dye intermediate,photosensitive compound,and is widely used in the fields of electronics,medicine,chemical,textile etc.With the increasing demand of hydrogen peroxide in China,2-EAQ,as the main component of anthraquinone working fluid,is widely demanded.The traditional industrial production method of 2-EAQ consists of two steps,in the second step,2-(4'-ethyl benzoyl)benzoic acid(BEA)which was formed in the first step was then dehydrated with fuming H2SO4 or concentrated H2SO4 as catalysts for the synthesis of2-EAQ.The second step will produce a lot of waste acid,which not only causes the corrosion of the equipment,but also brings serious environmental pollution problems.In this paper,Beta,mordenite,ZSM-5 and other zeolites were firstly used as catalysts for the synthesis of 2-EAQ.When compared,Beta and mordenite showed better catalytic performance in the reaction because of similar pore size as raw materials and products.Then different concentration of oxalic acid solution were used to modify Beta zeolite and mordenite.The results showed that the yield of 2-EAQ could be increased by three times when using appropriate concentration of oxalic acid solution.When the samples were treated with oxalic acid,the framework aluminum of Beta zeolite was removed,and the number of strong acid sites of the zeolite were reduced,the strong adsorption of the product on the acid site was avoided,and the deactivation rate of the catalyst was reduced.Secondly,sodium exchange modification strategy was used,it proved that dehydration of BEA synthesis of2-EAQ reaction catalysed by Beta zeolite mainly occured at the acid sites on inner surface of catalyst.In order to further explore contribution of the acid sites on inner surface and outer surface for the reaction performance,samples were modified by silicon and three phenyl phosphate(TPP).Three phenyl phosphate modification achieved surface passivation with no effect on pore structure,and improved the performance of catalysts in a certain extent.When the reaction is carried out in the absence of solvent,high viscosity of reaction system brought great difficulty in separation of the products,and caused congestion easily,which was not conducive to the industrialization operation.Therefore,this paper finally tried to use solvent method instead of solvent-free method for synthesis of 2-EAQ,and discussed theinfluence of different solvents in the reaction.