Abstract: Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene (2,6-DIPN) is a raw material for the production of advanced polyester materials such as PEN and liquid crystal polymers.In this study, the preparation of 2,6-DIPN through the isopropylation of industrial refined naphthalene with propylene was conducted in 0.5 L autoclave with steam dealuminated H-mordenite (SDHM) as the shape-selective catalyst instead of the conventional Friedel-Crafts catalysts and resulted in high selectivity and high yield of 2,6-DIPN.In order to slacken the deactivation of HM, the reaction was carried out in H2 atmosphere.The dehydrogenation of fused-ring polycyclics could be minimized and coke formation could be reduced.The preferred reaction conditions found were temperature of 275—300 ℃,hydrogen pressure of 0.4 MPa,reaction time of 7—8 h and 6%—7% of SDHM by mass,in which no side reactions were observed. From NH₃-TPD profiles,it could be seen that the relative strength of strong acid sites of SDHM in hydrogen isopropylation was greater than that in nitrogen isopropylation after the same reaction period.Comparing with the results obtained in nitrogen atmosphere, the conversion of refined naphthalene and yield of 2,6-DIPN could be remarkably increased to an average value as high as 90 % and 35 % respectively.Hence the catalytic activity of SDHM could be maintained for a longer time in H₂ atmosphere.