Abstract
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.
Highlights
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
X-ray powder diffraction (XRD) patterns of as-synthesized SAPO-5 and SAPO-11 samples presented in Figure 1 show the presence of highly crystalline SAPO phases and no impurity phases are detected
The BET surface area and the pore volume of SAPO11, SAPO-5 and Mordenite molecular sieves are determined by N2 adsorption-desorption measurement
Summary
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. They were investigated in detail by using ammonia temperature programmed desorption (NH3-TPD), infrared spectroscopy with pyridine adsorption (Py-IR) and N2 adsorption techniques in order to study the impact of the pore structure and acidity of molecular sieves on catalytic performance in the methylation of naphthalene with methanol.
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