Synthesis of 2,6-dimethylnaphthalene over SAPO-11, SAPO-5 and mordenite molecular sieves

Abstract

Shape-selective methylation of naphthalene over SAPO-11, SAPO-5 and mordenite molecular sieves were carried out in a fixed-bed flow reactor under atmospheric pressure. Methanol and mesitylene were used as methylation and solvent agents. The experiment results showed that SAPO-11 exhibited higher stability, higher selectivity of 2,6-dimethylnaphthalene (2,6-DMN) and higher 2,6-/2,7-DMN ratio than SAPO-5 and mordenite molecular sieves. The catalytic performances for the methylation of naphthalene were mainly related to the pore structure of the catalysts. The comparison of the spent SAPO- 11 with fresh SAPO- 11 suggested that structure collapse of the SAPO-11 by dealumination was occurred during the methylation of naphthalene with methanol, which may have been caused by high temperature steam from water produced in the reaction or by high temperature methanol vapor.