Promoted metal utilization capacity of alkali-treated zeolite: Preparation of Zn/ZSM-5 and its application in 1-hexene aromatization

Promoted metal utilization capacity of ZSM-5 zeolite has been achieved via the intracrystalline mesopores created by alkali treatment. The untreated and alkali-treated Zn/ZSM-5 catalysts were prepared by the conventional liquid ion exchange and impregnation methods. These catalysts were investigated by several techniques: N2 adsorption–desorption, transmission electron microscopy, X-ray photoelectron spectroscopy, ammonia temperature-programmed desorption, and Fourier transform infrared spectroscopy. Compared with the untreated catalysts, the alkali-treated catalysts exhibited higher Zn-loading in liquid ion exchange, better metal distribution and more Lewis acid sites in impregnation, owing to the location of Zn species in the created intracrystalline mesopores. The alkali-treated Zn/ZSM-5 catalysts displayed dramatically improved catalytic stability in 1-hexene aromatization. These findings show new potential for developing some advanced bifunctional metal-zeolite catalysts by a facile and low-cost method.