The dealumination of HZSM-12 zeolite (Si/Al = 65) was carried Out with citric acid and hydrochloric acid The structure and acidity were characterized by XRD, XRF, SEM, N-2-adsorption. NH3-TPD, Py-IR and Si-29 MAS NMR The zeolites' catalytic properties were Studied using the methylation of naphthalene to prepare 2,6-dimethylnaphthalene as a test reaction The results show that the two kinds of acid call remove the framework Al of and decrease the amount of Bronsted acid sites. while not destroying the framework Structure of the zeolite under the proper conditions Hydrochloric acid removed both the strong and weak acid sites Simultaneously, resulting ill improved catalytic stability in the methylation of naphthalene (NAPH). In contrast. the citric acid preferred to remove the strongly acid sites and also formed secondary mesopores in the sample. resulting in improved reaction performance. Under the proper reaction conditions including a reaction temperature of 350 degrees C, a reaction pressure of 4 MPa, a nitrogen flow rate of 10 mL/mtn. NAPH CH3OH 1,2,4-TMB 1.2 8 (mol), and WSHV = 3 h(-1) with a reaction time of 4 h, the conversion of naphthalene was 30.5% and the ratio of 2,6-/2,7-DMN was 1 83 over dealuminated HZSM-12 by 10 mol/L hydrochloric acid for 6 h (C) 2009 Elsevier B.V All rights reserved