Methylation of naphthalene on MTW-type zeolites. Influence of template origin and substitution of Al by Ga Original Research Article

Two templates, methyltriethylammonium bromide (MTEA) and tetraethylammonium bromide (TEA) were used to synthesize aluminosilicate ZSM-12 zeolites. Additionally, zeolites isomorphously substituted (partially or totally) by gallium were prepared with MTEA. Various techniques including XRD, scanning electron microscopy (SEM), N2 adsorption, NH3-TPD, Fourier transform infrared (FTIR) spectroscopy and MAS NMR were used to monitor the physico-chemical properties of these solids. Catalytic properties of the prepared zeolites were studied in the methylation of naphthalene. Higher conversion of naphthalene, higher content of 2,6-DMN among total DMNs and higher 2,6-/2,7-DMN ratio were observed on Al-TEA sample and on Ga-containing zeolites compared to Al-MTEA. The specific morphology of zeolite crystals and the presence of secondary mesopores were identified to be responsible for remarkable catalytic performance of MTW-type zeolites.