Shaped binderless ZSM-11 zeolite catalyst prepared via a dry-gel conversion method: Characterization and application for alkylation of benzene with dimethyl ether

摘要

Shaped binderless ZSM-11 zeolite catalysts were synthesized via a dry-gel conversion technique from 70ZSM-11/30SiO2mix extrudates.1,6-hexanediamine combined with tetrabutylammonium bromide was proved to be the best structure directing agent for the synthesis of the binderless ZSM-11 catalyst,without adding other alkaline materials.The 70HZSM-11/30SiO2mix serials materials crystallized for different times were detected by X-ray diffraction (XRD),nuclear magnetic resonance (NMR),scanning electron microscopy (SEM),transmission electron microscopy (TEM),scanning transmission electron microscopyenergy dispersive spectroscopy (STEM-EDS) techniques,and so on.In order to investigate the possible crystallization mechanism,the textural and structural properties of 70HZSM-11/30SiO2mix serials samples were further characterized by N2 adsorption-desorption.Acid properties were determined by temperature-programed desorption of NH3 (NH3-TPD) and pyridine adsorption-infrared (Py-IR) measurements.In the alkylation of benzene with dimethyl ether,the serials catalysts exhibited different benzene conversions.70HZSM-11/30SiO2mix showed the lowest benzene conversion while sample 70HZSM-11/30SiO2 mix-6.5h synthesized only for 6.5h displayed a higher benzene conversion,even higher than the value over 70HZSM-11/B0Al2O3mix.Extending the crystallization time,the obtained samples displayed the increased benzene conversion in general under the same reaction conditions.In the end,the relation of physicochemical properties with the reaction performance was investigated.