Method for preparing long-chain alkyl naphthalene through alkylation of naphthalene and long-chain alpha-olefin

The invention relates to a method for preparing long-chain alkyl naphthalene through alkylation of naphthalene and long-chain alpha-olefin. The method is characterized in that a mixture containing long-chain alpha-olefin, naphthalene and a solvent passes through a Y-type molecular sieve catalyst of which the average particle size is 100-400nm and the silica-alumina ratio is greater than or equal to 8.0 to obtain a product containing long-chain alkyl naphthalene. The preferable preparation method of the catalyst comprises the steps of synthesizing the NaY molecular sieve with high silica-alumina ratio and small crystal grains and carrying out three-step acid-base modification treatment. By adopting the method, the number of active centers on the surface of the catalyst is effectively increased, the intragranular diffusion rate is improved, and the generation of coke is remarkably reduced. In the reaction for synthesizing the octylnaphthalene, the conversion rate of 1-octylene can reach 100%, the selectivity of