Highly selective synthesis of 2,6-dimethylnaphthalene over alkaline treated ZSM-12 zeolite

ZSM-12 zeolites synthesized by using different templates were modified by desilication treatment in alkaline medium. The samples before and after alkaline treatment were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), N2 physical adsorption, solid state NMR (29Si MAS NMR), ammonia temperature programmed desorption (NH3-TPD) and FT-IR spectroscopy of adsorbed pyridine (Py-IR). The effects of desilication on the structure, acidity and catalytic performance in the alkylation of naphthalene with methanol over ZSM-12 zeolites were investigated. The results showed that acidity of ZSM-12 zeolites could be adjusted and mesopores were generated after alkaline treatment, so catalytic performance was effectively improved, and increase of naphthalene conversion, selectivity to 2,6-DMN and 2,6-/2,7-DMN ratio were observed over the alkaline treated samples.