The invention relates to a method for preparing 2-ethyl 
anthraquinone with a one-
step method, in particular to a method for preparing the 2-ethyl 
anthraquinone through a one-step reaction of 
ethylbenzene and 
phthalic anhydride under 
catalysis of an alkali desilication modified Hbeta 
molecular sieve, and aims to solve technical problems that the production technology is complex, a large amount of acid 
wastewater is produced, equipment is corroded severely, catalysts cannot be recycled and continuity of the production process cannot be realized due to the fact that two homogeneous catalysts, namely, 
anhydrous aluminum trichloride and concentrated 
sulfuric acid, are used respectively when the 2-ethyl 
anthraquinone is prepared through a two-step reaction of the 
ethylbenzene and the 
phthalic anhydride at present. The method comprises steps as follows: the 
phthalic anhydride and the 
ethylbenzene are evenly mixed, then the catalyst, namely, the alkali desilication modified Hbeta 
molecular sieve, is added, the mixture reacts at the 
reaction temperature of 170-230 DEG C for 1.2-5 h, a 
solid-liquid mixture is obtained, the 
solid catalyst, namely, the alkali desilication modified Hbeta 
molecular sieve, is separated after cooling, and the 2-ethyl anthraquinone is obtained. The method is mild in reaction condition, high in product yield and high in phthalic anhydride conversion rate.